[gndoc] Update GN build arguments documentation

Test: CQ

Change-Id: I7251707435f7739d0a36541a0ff47ec0c41c8561
diff --git a/docs/gen/build_arguments.md b/docs/gen/build_arguments.md
index 3ffe1a1..1119009 100644
--- a/docs/gen/build_arguments.md
+++ b/docs/gen/build_arguments.md
@@ -2,40 +2,269 @@
 
 ## All builds
 
+### scenic_vulkan_swapchain
+
+**Current value (from the default):** `1`
+
+From [//garnet/lib/ui/gfx/BUILD.gn:12](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/ui/gfx/BUILD.gn#12)
+
+### use_goma
+Set to true to enable distributed compilation using Goma.
+
+**Current value (from the default):** `false`
+
+From [//build/toolchain/goma.gni:9](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/toolchain/goma.gni#9)
+
+### use_prebuilt_ffmpeg
+Use a prebuilt ffmpeg binary rather than building it locally.  See
+[//garnet/bin/mediaplayer/ffmpeg/README.md](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/bin/mediaplayer/ffmpeg/README.md) for details.  This is
+ignored when building media_player in variant builds (e.g. sanitizers);
+in that case, ffmpeg is always built from source so as to be built with
+the selected variant's config.  When this is false (either explicitly
+or because media_player is a variant build) then //third_party/ffmpeg
+must be in the source tree, which requires:
+`jiri import -name garnet manifest/ffmpeg https://fuchsia.googlesource.com/garnet`
+
+**Current value (from the default):** `true`
+
+From [//garnet/bin/mediaplayer/ffmpeg/BUILD.gn:14](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/bin/mediaplayer/ffmpeg/BUILD.gn#14)
+
+### zircon_tools_dir
+Where to find Zircon's host-side tools that are run as part of the build.
+
+**Current value (from the default):** `"//out/build-zircon/tools"`
+
+From [//build/config/fuchsia/zircon.gni:9](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/fuchsia/zircon.gni#9)
+
+### zircon_use_asan
+Set this if [`zircon_build_dir`](#zircon_build_dir) was built with
+`USE_ASAN=true`, e.g. `[//scripts/build-zircon.sh](https://fuchsia.googlesource.com/scripts/+/c04e34ca6e090f0c5c9734fbf9dde8d93df8490d/build-zircon.sh) -A`.  This mainly
+affects the defaults for [`zircon_build_dir`](#zircon_build_dir) and
+[`zircon_build_abi_dir`](#zircon_build_abi_dir).  It also gets noticed
+by [//scripts/fx](https://fuchsia.googlesource.com/scripts/+/c04e34ca6e090f0c5c9734fbf9dde8d93df8490d/fx) commands that rebuild Zircon so that they use `-A`
+again next time.
+
+**Current value (from the default):** `false`
+
+From [//build/config/fuchsia/zircon.gni:40](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/fuchsia/zircon.gni#40)
+
+### custom_signing_script
+If non-empty, the given script will be invoked to produce a signed ZBI
+image. The given script must accept -z for the input zbi path, and -o for
+the output signed zbi path. The path must be in GN-label syntax (i.e.
+starts with //).
+
+**Current value (from the default):** `""`
+
+From [//build/images/custom_signing.gni:10](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/custom_signing.gni#10)
+
+### magma_build_root
+
+**Current value (from the default):** `"//garnet/lib/magma"`
+
+From [//garnet/lib/magma/gnbuild/magma.gni:6](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/magma/gnbuild/magma.gni#6)
+
+### fvm_slice_size
+The size of the FVM partition images "slice size". The FVM slice size is a
+minimum size of a particular chunk of a partition that is stored within
+FVM. A very small slice size may lead to decreased throughput. A very large
+slice size may lead to wasted space. The selected default size of 8mb is
+selected for conservation of space, rather than performance.
+
+**Current value (from the default):** `"8388608"`
+
+From [//build/images/BUILD.gn:581](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#581)
+
+### select_variant_shortcuts
+List of short names for commonly-used variant selectors.  Normally this
+is not set as a build argument, but it serves to document the available
+set of short-cut names for variant selectors.  Each element of this list
+is a scope where `.name` is the short name and `.select_variant` is a
+a list that can be spliced into [`select_variant`](#select_variant).
+
+**Current value (from the default):**
+```
+[{
+  name = "host_asan"
+  select_variant = [{
+  dir = ["//third_party/yasm", "//third_party/vboot_reference", "//garnet/tools/vboot_reference"]
+  host = true
+  variant = "asan_no_detect_leaks"
+}, {
+  host = true
+  variant = "asan"
+}]
+}, {
+  name = "asan"
+  select_variant = [{
+  target_type = ["driver_module"]
+  variant = false
+}, {
+  host = false
+  variant = "asan"
+}]
+}]
+```
+
+From [//build/config/BUILDCONFIG.gn:439](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/BUILDCONFIG.gn#439)
+
+### universal_variants
+
+**Current value (from the default):**
+```
+[{
+  configs = []
+  name = "release"
+  toolchain_args = {
+  is_debug = false
+}
+}]
+```
+
+From [//build/config/BUILDCONFIG.gn:413](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/BUILDCONFIG.gn#413)
+
+### update_kernels
+List of kernel images to include in the update (OTA) package.
+If no list is provided, all built kernels are included. The names in the
+list are strings that must match the filename to be included in the update
+package.
+
+**Current value (from the default):** `[]`
+
+From [//build/images/BUILD.gn:367](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#367)
+
+### use_lto
+Use link time optimization (LTO).
+
+**Current value (from the default):** `false`
+
+From [//build/config/lto/config.gni:7](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/lto/config.gni#7)
+
+### build_intel_gen
+
+**Current value (from the default):** `false`
+
+From [//garnet/lib/magma/gnbuild/magma.gni:23](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/magma/gnbuild/magma.gni#23)
+
+### escher_use_null_vulkan_config_on_host
+Using Vulkan on host (i.e. Linux) is an involved affair that involves
+downloading the Vulkan SDK, setting environment variables, and so forth...
+all things that are difficult to achieve in a CQ environment.  Therefore,
+by default we use a stub implementation of Vulkan which fails to create a
+VkInstance.  This allows everything to build, and also allows running Escher
+unit tests which don't require Vulkan.
+
+**Current value (from the default):** `true`
+
+From [//garnet/public/lib/escher/BUILD.gn:15](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/public/lib/escher/BUILD.gn#15)
+
+### fvm_image_size
+The size in bytes of the FVM partition image to create. Normally this is
+computed to be just large enough to fit the blob and data images. The
+default value is "", which means to size based on inputs. Specifying a size
+that is too small will result in build failure.
+
+**Current value (from the default):** `""`
+
+From [//build/images/BUILD.gn:574](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#574)
+
+### ledger_sync_credentials_file
+
+**Current value (from the default):** `""`
+
+From [//peridot/bin/ledger/testing/sync_params.gni:6](https://fuchsia.googlesource.com/peridot/+/05b95387039dafd3c67104711e37c77f3eca13d5/bin/ledger/testing/sync_params.gni#6)
+
+### use_thinlto
+Use ThinLTO variant of LTO if use_lto = true.
+
+**Current value (from the default):** `true`
+
+From [//build/config/lto/config.gni:10](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/lto/config.gni#10)
+
+### dart_pool_depth
+Maximum number of Dart processes to run in parallel.
+
+Dart analyzer uses a lot of memory which may cause issues when building
+with many parallel jobs e.g. when using goma. To avoid out-of-memory
+errors we explicitly reduce the number of jobs.
+
+**Current value (from the default):** `16`
+
+From [//build/dart/toolchain.gni:11](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/dart/toolchain.gni#11)
+
+### extra_variants
+Additional variant toolchain configs to support.
+This is just added to [`known_variants`](#known_variants).
+
+**Current value (from the default):** `[]`
+
+From [//build/config/BUILDCONFIG.gn:393](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/BUILDCONFIG.gn#393)
+
+### prebuilt_libvulkan_arm_path
+
+**Current value (from the default):** `""`
+
+From [//garnet/lib/magma/gnbuild/magma.gni:25](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/magma/gnbuild/magma.gni#25)
+
+### use_scudo
+Enable the [Scudo](https://llvm.org/docs/ScudoHardenedAllocator.html)
+memory allocator.
+
+**Current value (from the default):** `true`
+
+From [//build/config/scudo/scudo.gni:8](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/scudo/scudo.gni#8)
+
+### data_image_size
+The size of the minfs data partition image to create. Normally this image
+is added to FVM, and can therefore expand as needed. It must be at least
+10mb (the default) in order to be succesfully initialized.
+
+**Current value (from the default):** `"10m"`
+
+From [//build/images/BUILD.gn:568](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#568)
+
+### enable_value_subsystem
+
+**Current value (from the default):** `false`
+
+From [//garnet/bin/ui/scenic/BUILD.gn:11](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/bin/ui/scenic/BUILD.gn#11)
+
+### crashpad_dependencies
+Determines various flavors of build configuration, and which concrete
+targets to use for dependencies. Valid values are "standalone",
+"chromium", and "fuchsia". Defaulted to "fuchsia" because
+"is_fuchsia_tree" is set.
+
+**Current value (from the default):** `"fuchsia"`
+
+From [//third_party/crashpad/build/crashpad_buildconfig.gni:26](https://chromium.googlesource.com/crashpad/crashpad/+/95b177e79398fe3fd042936ae5bf22c6252a7720/build/crashpad_buildconfig.gni#26)
+
 ### current_cpu
 
 **Current value (from the default):** `""`
 
-### extra_manifest_args
-Extra args to globally apply to the manifest generation script.
+### current_os
 
-**Current value (from the default):** `[]`
+**Current value (from the default):** `""`
 
-From [//build/images/manifest.gni:47](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/manifest.gni#47)
+### scenic_ignore_vsync
 
-### icu_use_data_file
-Tells icu to load an external data file rather than rely on the icudata
-being linked directly into the binary.
+**Current value (from the default):** `false`
 
-This flag is a bit confusing. As of this writing, icu.gyp set the value to
-0 but common.gypi sets the value to 1 for most platforms (and the 1 takes
-precedence).
+From [//garnet/lib/ui/gfx/BUILD.gn:16](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/ui/gfx/BUILD.gn#16)
 
-TODO(GYP) We'll probably need to enhance this logic to set the value to
-true or false in similar circumstances.
+### always_zedboot
+Build boot images that prefer Zedboot over local boot (only for EFI).
 
-**Current value (from the default):** `true`
+**Current value (from the default):** `false`
 
-From [//third_party/icu/config.gni:15](https://fuchsia.googlesource.com/third_party/icu/+/15006476e9d2f5c7d6691f3658fecff4929aaf68/config.gni#15)
+From [//build/images/BUILD.gn:584](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#584)
 
-### kernel_cmdline_args
-List of kernel command line arguments to bake into the boot image.
-See also [//zircon/docs/kernel_cmdline.md](https://fuchsia.googlesource.com/zircon/+/2b80ad3e9e48eff77a0cb4dade6f53a2095e4c18/docs/kernel_cmdline.md) and
-[`devmgr_config`](#devmgr_config).
+### cloudkms_key_dir
 
-**Current value (from the default):** `[]`
+**Current value (from the default):** `"projects/fuchsia-infra/locations/global/keyRings/test-secrets/cryptoKeys"`
 
-From [//build/images/BUILD.gn:349](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#349)
+From [//build/testing/secret_spec.gni:8](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/testing/secret_spec.gni#8)
 
 ### known_variants
 List of variants that will form the basis for variant toolchains.
@@ -150,73 +379,79 @@
 
 From [//build/config/BUILDCONFIG.gn:334](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/BUILDCONFIG.gn#334)
 
-### scenic_enable_vulkan_validation
-Include the vulkan validation layers in scenic even in release builds
-TODO(SCN-1003): Set the default to false once we know why disabling
-validation layers causes a display swapchain setup issue.
-
-**Current value (from the default):** `true`
-
-From [//garnet/bin/ui/BUILD.gn:12](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/bin/ui/BUILD.gn#12)
-
-### amber_repository_blobs_dir
-
-**Current value (from the default):** `"//root_build_dir/amber-files/repository/blobs"`
-
-From [//garnet/go/src/amber/amber.gni:16](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/go/src/amber/amber.gni#16)
-
-### kernel_cmdline_files
-Files containing additional kernel command line arguments to bake into
-the boot image.  The contents of these files (in order) come after any
-arguments directly in [`kernel_cmdline_args`](#kernel_cmdline_args).
-These can be GN `//` source pathnames or absolute system pathnames.
-
-**Current value (from the default):** `[]`
-
-From [//build/images/BUILD.gn:355](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#355)
-
-### system_package_key
-The package key to use for signing Fuchsia packages made by the
-`package()` template (and the `system_image` packge).  If this
-doesn't exist yet when it's needed, it will be generated.  New
-keys can be generated with the `pm -k FILE genkey` host command.
-
-**Current value (from the default):** `"//build/development.key"`
-
-From [//build/package.gni:16](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/package.gni#16)
-
-### target_sysroot
-The absolute path of the sysroot that is used with the target toolchain.
-
-**Current value (from the default):** `""`
-
-From [//build/config/sysroot.gni:7](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/sysroot.gni#7)
-
-### use_goma
-Set to true to enable distributed compilation using Goma.
+### magma_enable_developer_build
+Enable this to have the msd include a suite of tests and invoke them
+automatically when the driver starts.
 
 **Current value (from the default):** `false`
 
-From [//build/toolchain/goma.gni:9](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/toolchain/goma.gni#9)
+From [//garnet/lib/magma/gnbuild/magma.gni:19](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/magma/gnbuild/magma.gni#19)
+
+### magma_python_path
+
+**Current value (from the default):** `"/b/s/w/ir/kitchen-workdir/third_party/mako"`
+
+From [//garnet/lib/magma/gnbuild/magma.gni:12](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/magma/gnbuild/magma.gni#12)
+
+### target_cpu
+
+**Current value for `target_cpu = "arm64"`:** `"arm64"`
+
+From //root_build_dir/args.gn:1
+
+**Overridden from the default:** `""`
+
+**Current value for `target_cpu = "x64"`:** `"x64"`
+
+From //root_build_dir/args.gn:1
+
+**Overridden from the default:** `""`
+
+### target_os
+
+**Current value (from the default):** `""`
+
+### zedboot_cmdline_args
+List of kernel command line arguments to bake into the Zedboot image.
+See [//zircon/docs/kernel_cmdline.md](https://fuchsia.googlesource.com/zircon/+/2b80ad3e9e48eff77a0cb4dade6f53a2095e4c18/docs/kernel_cmdline.md) and
+[`zedboot_devmgr_config`](#zedboot_devmgr_config).
+
+**Current value (from the default):** `[]`
+
+From [//build/images/zedboot/BUILD.gn:15](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/zedboot/BUILD.gn#15)
+
+### build_msd_arm_mali
+
+**Current value (from the default):** `true`
+
+From [//garnet/lib/magma/gnbuild/magma.gni:21](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/magma/gnbuild/magma.gni#21)
+
+### is_debug
+Debug build.
+
+**Current value (from the default):** `true`
+
+From [//build/config/BUILDCONFIG.gn:11](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/BUILDCONFIG.gn#11)
+
+### zircon_build_dir
+Zircon build directory for `target_cpu`, containing `.manifest` and
+`.zbi` files for Zircon's BOOTFS and kernel.  This provides the kernel
+and Zircon components used in the boot image.  It also provides the
+Zircon shared libraries used at runtime in Fuchsia packages.
+
+If left `""` (the default), then this is computed from
+[`zircon_build_abi_dir`](#zircon_build_abi_dir) and
+[`zircon_use_asan`](#zircon_use_asan).
+
+**Current value (from the default):** `""`
+
+From [//build/config/fuchsia/zircon.gni:24](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/fuchsia/zircon.gni#24)
 
 ### zircon_build_root
 
 **Current value (from the default):** `"//zircon"`
 
-From [//garnet/lib/magma/gnbuild/magma.gni:10](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/magma/gnbuild/magma.gni#10)
-
-### enable_value_subsystem
-
-**Current value (from the default):** `false`
-
-From [//garnet/bin/ui/scenic/BUILD.gn:11](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/bin/ui/scenic/BUILD.gn#11)
-
-### magma_enable_tracing
-Enable this to include fuchsia tracing capability
-
-**Current value (from the default):** `true`
-
-From [//garnet/lib/magma/gnbuild/magma.gni:15](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/magma/gnbuild/magma.gni#15)
+From [//garnet/lib/magma/gnbuild/magma.gni:10](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/magma/gnbuild/magma.gni#10)
 
 ### zircon_aux_manifests
 
@@ -224,44 +459,56 @@
 
 From [//build/images/manifest.gni:32](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/manifest.gni#32)
 
-### build_intel_gen
-
-**Current value (from the default):** `false`
-
-From [//garnet/lib/magma/gnbuild/magma.gni:23](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/magma/gnbuild/magma.gni#23)
-
-### custom_signing_script
-If non-empty, the given script will be invoked to produce a signed ZBI
-image. The given script must accept -z for the input zbi path, and -o for
-the output signed zbi path. The path must be in GN-label syntax (i.e.
-starts with //).
-
-**Current value (from the default):** `""`
-
-From [//build/images/custom_signing.gni:10](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/custom_signing.gni#10)
-
-### rustc_prefix
-Sets a custom base directory for `rustc` and `cargo`.
-This can be used to test custom Rust toolchains.
-
-**Current value (from the default):** `"//buildtools/linux-x64/rust/bin"`
-
-From [//build/rust/config.gni:17](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/rust/config.gni#17)
-
-### use_ccache
-Set to true to enable compiling with ccache
-
-**Current value (from the default):** `false`
-
-From [//build/toolchain/ccache.gni:9](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/toolchain/ccache.gni#9)
-
-### use_scudo
-Enable the [Scudo](https://llvm.org/docs/ScudoHardenedAllocator.html)
-memory allocator.
+### use_vulkan_loader_for_tests
+Mesa doesn't properly handle loader-less operation;
+their GetInstanceProcAddr implementation returns 0 for some interfaces.
+On ARM there may be multiple libvulkan_arms, so they can't all be linked
+to.
 
 **Current value (from the default):** `true`
 
-From [//build/config/scudo/scudo.gni:8](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/scudo/scudo.gni#8)
+From [//garnet/lib/magma/gnbuild/magma.gni:33](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/magma/gnbuild/magma.gni#33)
+
+### zircon_asan_build_dir
+Zircon `USE_ASAN=true` build directory for `target_cpu` containing
+`bootfs.manifest` with libraries and `devhost.asan`.
+
+If left `""` (the default), then this is computed from
+[`zircon_build_dir`](#zircon_build_dir) and
+[`zircon_use_asan`](#zircon_use_asan).
+
+**Current value (from the default):** `""`
+
+From [//build/config/fuchsia/zircon.gni:32](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/fuchsia/zircon.gni#32)
+
+### scudo_default_options
+Default [Scudo](https://llvm.org/docs/ScudoHardenedAllocator.html)
+options (before the `SCUDO_OPTIONS` environment variable is read at
+runtime).  *NOTE:* This affects only components using the `scudo`
+variant (see GN build argument `select_variant`), and does not affect
+anything when the `use_scudo` build flag is set instead.
+
+**Current value (from the default):** `["abort_on_error=1", "QuarantineSizeKb=0", "ThreadLocalQuarantineSizeKb=0", "DeallocationTypeMismatch=false", "DeleteSizeMismatch=false", "allocator_may_return_null=true"]`
+
+From [//build/config/scudo/scudo.gni:15](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/scudo/scudo.gni#15)
+
+### select_variant_canonical
+*This should never be set as a build argument.*
+It exists only to be set in `toolchain_args`.
+See [//build/toolchain/clang_toolchain.gni](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/toolchain/clang_toolchain.gni) for details.
+
+**Current value (from the default):** `[]`
+
+From [//build/config/BUILDCONFIG.gn:618](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/BUILDCONFIG.gn#618)
+
+### amber_repository_dir
+Directory containing files named by their merkleroot content IDs in
+ASCII hex.  The [//build/image](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/image):amber_publish_blobs target populates
+this with copies of build products, but never removes old files.
+
+**Current value (from the default):** `"//root_build_dir/amber-files"`
+
+From [//garnet/go/src/amber/amber.gni:11](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/go/src/amber/amber.gni#11)
 
 ### bootfs_extra
 List of extra manifest entries for files to add to the BOOTFS.
@@ -273,13 +520,168 @@
 
 From [//build/images/BUILD.gn:361](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#361)
 
+### enable_sketchy_subsystem
+
+**Current value (from the default):** `true`
+
+From [//garnet/bin/ui/scenic/BUILD.gn:13](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/bin/ui/scenic/BUILD.gn#13)
+
+### goma_dir
+Absolute directory containing the Goma source code.
+
+**Current value (from the default):** `"/home/swarming/goma"`
+
+From [//build/toolchain/goma.gni:12](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/toolchain/goma.gni#12)
+
+### icu_use_data_file
+Tells icu to load an external data file rather than rely on the icudata
+being linked directly into the binary.
+
+This flag is a bit confusing. As of this writing, icu.gyp set the value to
+0 but common.gypi sets the value to 1 for most platforms (and the 1 takes
+precedence).
+
+TODO(GYP) We'll probably need to enhance this logic to set the value to
+true or false in similar circumstances.
+
+**Current value (from the default):** `true`
+
+From [//third_party/icu/config.gni:15](https://fuchsia.googlesource.com/third_party/icu/+/15006476e9d2f5c7d6691f3658fecff4929aaf68/config.gni#15)
+
+### msd_intel_gen_build_root
+
+**Current value (from the default):** `"//garnet/drivers/gpu/msd-intel-gen"`
+
+From [//garnet/lib/magma/gnbuild/magma.gni:8](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/magma/gnbuild/magma.gni#8)
+
+### rust_lto
+Sets the default LTO type for rustc bulids.
+
+**Current value (from the default):** `"unset"`
+
+From [//build/rust/config.gni:20](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/rust/config.gni#20)
+
+### scenic_enable_vulkan_validation
+Include the vulkan validation layers in scenic even in release builds
+TODO(SCN-1003): Set the default to false once we know why disabling
+validation layers causes a display swapchain setup issue.
+
+**Current value (from the default):** `true`
+
+From [//garnet/bin/ui/BUILD.gn:12](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/bin/ui/BUILD.gn#12)
+
+### amber_repository_blobs_dir
+
+**Current value (from the default):** `"//root_build_dir/amber-files/repository/blobs"`
+
+From [//garnet/go/src/amber/amber.gni:16](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/go/src/amber/amber.gni#16)
+
+### build_vsl_gc
+
+**Current value (from the default):** `true`
+
+From [//garnet/lib/magma/gnbuild/magma.gni:22](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/magma/gnbuild/magma.gni#22)
+
+### toolchain_variant
+*This should never be set as a build argument.*
+It exists only to be set in `toolchain_args`.
+See [//build/toolchain/clang_toolchain.gni](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/toolchain/clang_toolchain.gni) for details.
+This variable is a scope giving details about the current toolchain:
+    `toolchain_variant.base`
+        [label] The "base" toolchain for this variant, *often the
+        right thing to use in comparisons, not `current_toolchain`.*
+        This is the toolchain actually referenced directly in GN
+        source code.  If the current toolchain is not
+        `shlib_toolchain` or a variant toolchain, this is the same
+        as `current_toolchain`.  In one of those derivative
+        toolchains, this is the toolchain the GN code probably
+        thought it was in.  This is the right thing to use in a test
+        like `toolchain_variant.base == target_toolchain`, rather
+        rather than comparing against `current_toolchain`.
+    `toolchain_variant.name`
+        [string] The name of this variant, as used in `variant` fields
+        in [`select_variant`](#select_variant) clauses.  In the base
+        toolchain and its `shlib_toolchain`, this is `""`.
+    `toolchain_variant.suffix`
+        [string] This is "-${toolchain_variant.name}", "" if name is empty.
+    `toolchain_variant.is_pic_default`
+        [bool] This is true in `shlib_toolchain`.
+The other fields are the variant's effects as defined in
+[`known_variants`](#known_variants).
+
+**Current value (from the default):**
+```
+{
+  base = "//build/toolchain/fuchsia:arm64"
+}
+```
+
+From [//build/config/BUILDCONFIG.gn:71](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/BUILDCONFIG.gn#71)
+
+### use_ccache
+Set to true to enable compiling with ccache
+
+**Current value (from the default):** `false`
+
+From [//build/toolchain/ccache.gni:9](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/toolchain/ccache.gni#9)
+
+### target_sysroot
+The absolute path of the sysroot that is used with the target toolchain.
+
+**Current value (from the default):** `""`
+
+From [//build/config/sysroot.gni:7](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/sysroot.gni#7)
+
+### thinlto_cache_dir
+ThinLTO cache directory path.
+
+**Current value (from the default):** `"arm64-shared/thinlto-cache"`
+
+From [//build/config/lto/config.gni:16](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/lto/config.gni#16)
+
 ### host_cpu
 
 **Current value (from the default):** `"x64"`
 
-### host_os
+### kernel_cmdline_args
+List of kernel command line arguments to bake into the boot image.
+See also [//zircon/docs/kernel_cmdline.md](https://fuchsia.googlesource.com/zircon/+/2b80ad3e9e48eff77a0cb4dade6f53a2095e4c18/docs/kernel_cmdline.md) and
+[`devmgr_config`](#devmgr_config).
 
-**Current value (from the default):** `"linux"`
+**Current value (from the default):** `[]`
+
+From [//build/images/BUILD.gn:349](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#349)
+
+### devmgr_config
+List of arguments to add to /boot/config/devmgr.
+These come after synthesized arguments to configure blobfs and pkgfs,
+and the one generated for [`enable_crashpad`](#enable_crashpad).
+
+**Current value (from the default):** `[]`
+
+From [//build/images/BUILD.gn:344](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#344)
+
+### host_byteorder
+
+**Current value (from the default):** `"undefined"`
+
+From [//build/config/host_byteorder.gni:7](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/host_byteorder.gni#7)
+
+### crashpad_use_boringssl_for_http_transport_socket
+
+**Current value (from the default):** `true`
+
+From [//third_party/crashpad/util/net/tls.gni:18](https://chromium.googlesource.com/crashpad/crashpad/+/95b177e79398fe3fd042936ae5bf22c6252a7720/util/net/tls.gni#18)
+
+### sdk_dirs
+The directories to search for parts of the SDK.
+
+By default, we search the public directories for the various layers.
+In the future, we'll search a pre-built SDK as well.
+
+**Current value (from the default):** `["//garnet/public", "//peridot/public", "//topaz/public"]`
+
+From [//build/config/fuchsia/sdk.gni:10](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/fuchsia/sdk.gni#10)
 
 ### thinlto_jobs
 Number of parallel ThinLTO jobs.
@@ -288,19 +690,148 @@
 
 From [//build/config/lto/config.gni:13](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/lto/config.gni#13)
 
-### use_prebuilt_ffmpeg
-Use a prebuilt ffmpeg binary rather than building it locally.  See
-[//garnet/bin/mediaplayer/ffmpeg/README.md](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/bin/mediaplayer/ffmpeg/README.md) for details.  This is
-ignored when building media_player in variant builds (e.g. sanitizers);
-in that case, ffmpeg is always built from source so as to be built with
-the selected variant's config.  When this is false (either explicitly
-or because media_player is a variant build) then //third_party/ffmpeg
-must be in the source tree, which requires:
-`jiri import -name garnet manifest/ffmpeg https://fuchsia.googlesource.com/garnet`
+### zircon_boot_manifests
+Manifest files describing files to go into the `/boot` filesystem.
+Can be either // source paths or absolute system paths.
+`zircon_boot_groups` controls which files are actually selected.
+
+Since Zircon manifest files are relative to a Zircon source directory
+rather than to the directory containing the manifest, these are assumed
+to reside in a build directory that's a direct subdirectory of the
+Zircon source directory and thus their contents can be taken as
+relative to `get_path_info(entry, "dir") + "/.."`.
+
+**Current value (from the default):** `["//out/build-zircon/build-arm64/bootfs.manifest"]`
+
+From [//build/images/manifest.gni:44](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/manifest.gni#44)
+
+### amlogic_decoder_tests
+
+**Current value (from the default):** `false`
+
+From [//garnet/drivers/video/amlogic-decoder/BUILD.gn:10](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/drivers/video/amlogic-decoder/BUILD.gn#10)
+
+### build_libvulkan
+This is a list of targets that will be built as vulkan ICDS. If more than one
+target is given then use_vulkan_loader_for_tests must be set to true, as
+otherwise tests won't know which libvulkan to use.
+
+**Current value (from the default):** `[]`
+
+From [//garnet/lib/magma/gnbuild/magma.gni:38](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/magma/gnbuild/magma.gni#38)
+
+### extra_manifest_args
+Extra args to globally apply to the manifest generation script.
+
+**Current value (from the default):** `[]`
+
+From [//build/images/manifest.gni:47](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/manifest.gni#47)
+
+### zircon_asserts
 
 **Current value (from the default):** `true`
 
-From [//garnet/bin/mediaplayer/ffmpeg/BUILD.gn:14](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/bin/mediaplayer/ffmpeg/BUILD.gn#14)
+From [//build/config/fuchsia/BUILD.gn:138](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/fuchsia/BUILD.gn#138)
+
+### enable_gfx_subsystem
+
+**Current value (from the default):** `true`
+
+From [//garnet/bin/ui/scenic/BUILD.gn:12](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/bin/ui/scenic/BUILD.gn#12)
+
+### extra_authorized_keys_file
+Additional SSH authorized_keys file to include in the build.
+For example:
+  extra_authorized_keys_file=\"$HOME/.ssh/id_rsa.pub\"
+
+**Current value (from the default):** `""`
+
+From [//third_party/openssh-portable/fuchsia/developer-keys/BUILD.gn:11](https://fuchsia.googlesource.com/third_party/openssh-portable/+/baf903a4aff34287c9571060a961a836e6fec75f/fuchsia/developer-keys/BUILD.gn#11)
+
+### fuchsia_packages
+List of packages (a GN list of strings).
+This list of packages is added to the set of "available" packages, see
+`products` for more information.
+
+**Current value for `target_cpu = "arm64"`:** `["peridot/packages/buildbot"]`
+
+From //root_build_dir/args.gn:2
+
+**Overridden from the default:** `[]`
+
+From [//build/gn/packages.gni:30](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/gn/packages.gni#30)
+
+**Current value for `target_cpu = "x64"`:** `["peridot/packages/buildbot"]`
+
+From //root_build_dir/args.gn:2
+
+**Overridden from the default:** `[]`
+
+From [//build/gn/packages.gni:30](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/gn/packages.gni#30)
+
+### fuchsia_products
+List of product definition files describing the packages to build, and
+where they are to be installed in images and updates.
+
+A product definition file is a JSON file containing:
+monolith:
+  a list of packages included in OTA images, base system images, and the
+  distribution repository.
+preinstall:
+  a list of packages pre-installed on the system (also added to the
+  distribution repository)
+available:
+  a list of packages only added to the distribution repository)
+
+If a package is referenced in monolith and in preinstall, monolith takes
+priority, and the package will be added to OTA images as part of the
+verified boot set of static packages.
+
+If unset, layer will be guessed using //.jiri_manifest and
+//{layer}/products/default will be used.
+
+**Current value (from the default):** `[]`
+
+From [//build/gn/packages.gni:25](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/gn/packages.gni#25)
+
+### symbol_level
+How many symbols to include in the build. This affects the performance of
+the build since the symbols are large and dealing with them is slow.
+  2 means regular build with symbols.
+  1 means minimal symbols, usually enough for backtraces only. Symbols with
+internal linkage (static functions or those in anonymous namespaces) may not
+appear when using this level.
+  0 means no symbols.
+
+**Current value (from the default):** `2`
+
+From [//build/config/compiler.gni:13](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/compiler.gni#13)
+
+### vk_loader_debug
+
+**Current value (from the default):** `"warn,error"`
+
+From [//third_party/vulkan_loader_and_validation_layers/loader/BUILD.gn:26](https://fuchsia.googlesource.com/third_party/vulkan_loader_and_validation_layers/+/3106666ca09bdab1a0f3c4c5d4d614bf4dab1f3d/loader/BUILD.gn#26)
+
+### build_sdk_archives
+Whether to build SDK tarballs.
+
+**Current value (from the default):** `false`
+
+From [//build/sdk/sdk.gni:11](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/sdk/sdk.gni#11)
+
+### expat_build_root
+
+**Current value (from the default):** `"//third_party/expat"`
+
+From [//garnet/lib/magma/gnbuild/magma.gni:7](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/magma/gnbuild/magma.gni#7)
+
+### magma_enable_tracing
+Enable this to include fuchsia tracing capability
+
+**Current value (from the default):** `true`
+
+From [//garnet/lib/magma/gnbuild/magma.gni:15](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/magma/gnbuild/magma.gni#15)
 
 ### select_variant
 List of "selectors" to request variant builds of certain targets.
@@ -373,163 +904,30 @@
 
 From [//build/config/BUILDCONFIG.gn:613](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/BUILDCONFIG.gn#613)
 
-### toolchain_variant
-*This should never be set as a build argument.*
-It exists only to be set in `toolchain_args`.
-See [//build/toolchain/clang_toolchain.gni](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/toolchain/clang_toolchain.gni) for details.
-This variable is a scope giving details about the current toolchain:
-    `toolchain_variant.base`
-        [label] The "base" toolchain for this variant, *often the
-        right thing to use in comparisons, not `current_toolchain`.*
-        This is the toolchain actually referenced directly in GN
-        source code.  If the current toolchain is not
-        `shlib_toolchain` or a variant toolchain, this is the same
-        as `current_toolchain`.  In one of those derivative
-        toolchains, this is the toolchain the GN code probably
-        thought it was in.  This is the right thing to use in a test
-        like `toolchain_variant.base == target_toolchain`, rather
-        rather than comparing against `current_toolchain`.
-    `toolchain_variant.name`
-        [string] The name of this variant, as used in `variant` fields
-        in [`select_variant`](#select_variant) clauses.  In the base
-        toolchain and its `shlib_toolchain`, this is `""`.
-    `toolchain_variant.suffix`
-        [string] This is "-${toolchain_variant.name}", "" if name is empty.
-    `toolchain_variant.is_pic_default`
-        [bool] This is true in `shlib_toolchain`.
-The other fields are the variant's effects as defined in
-[`known_variants`](#known_variants).
+### system_package_key
+The package key to use for signing Fuchsia packages made by the
+`package()` template (and the `system_image` packge).  If this
+doesn't exist yet when it's needed, it will be generated.  New
+keys can be generated with the `pm -k FILE genkey` host command.
 
-**Current value (from the default):**
-```
-{
-  base = "//build/toolchain/fuchsia:arm64"
-}
-```
+**Current value (from the default):** `"//build/development.key"`
 
-From [//build/config/BUILDCONFIG.gn:71](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/BUILDCONFIG.gn#71)
+From [//build/package.gni:16](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/package.gni#16)
 
-### zircon_asan_build_dir
-Zircon `USE_ASAN=true` build directory for `target_cpu` containing
-`bootfs.manifest` with libraries and `devhost.asan`.
+### toolchain_manifests
+Manifest files describing target libraries from toolchains.
+Can be either // source paths or absolute system paths.
 
-If left `""` (the default), then this is computed from
-[`zircon_build_dir`](#zircon_build_dir) and
-[`zircon_use_asan`](#zircon_use_asan).
+**Current value (from the default):** `["/b/s/w/ir/kitchen-workdir/buildtools/linux-x64/clang/lib/aarch64-fuchsia.manifest"]`
 
-**Current value (from the default):** `""`
+From [//build/images/manifest.gni:11](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/manifest.gni#11)
 
-From [//build/config/fuchsia/zircon.gni:32](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/fuchsia/zircon.gni#32)
+### zedboot_devmgr_config
+List of arguments to populate /boot/config/devmgr in the Zedboot image.
 
-### symbol_level
-How many symbols to include in the build. This affects the performance of
-the build since the symbols are large and dealing with them is slow.
-  2 means regular build with symbols.
-  1 means minimal symbols, usually enough for backtraces only. Symbols with
-internal linkage (static functions or those in anonymous namespaces) may not
-appear when using this level.
-  0 means no symbols.
+**Current value (from the default):** `["netsvc.netboot=true"]`
 
-**Current value (from the default):** `2`
-
-From [//build/config/compiler.gni:13](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/compiler.gni#13)
-
-### amber_keys_dir
-Directory containing signing keys used by amber-publish.
-
-**Current value (from the default):** `"//garnet/go/src/amber/keys"`
-
-From [//garnet/go/src/amber/amber.gni:14](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/go/src/amber/amber.gni#14)
-
-### build_vsl_gc
-
-**Current value (from the default):** `true`
-
-From [//garnet/lib/magma/gnbuild/magma.gni:22](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/magma/gnbuild/magma.gni#22)
-
-### current_os
-
-**Current value (from the default):** `""`
-
-### escher_use_null_vulkan_config_on_host
-Using Vulkan on host (i.e. Linux) is an involved affair that involves
-downloading the Vulkan SDK, setting environment variables, and so forth...
-all things that are difficult to achieve in a CQ environment.  Therefore,
-by default we use a stub implementation of Vulkan which fails to create a
-VkInstance.  This allows everything to build, and also allows running Escher
-unit tests which don't require Vulkan.
-
-**Current value (from the default):** `true`
-
-From [//garnet/public/lib/escher/BUILD.gn:15](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/public/lib/escher/BUILD.gn#15)
-
-### fuchsia_packages
-List of packages (a GN list of strings).
-This list of packages is added to the set of "available" packages, see
-`products` for more information.
-
-**Current value for `target_cpu = "arm64"`:** `["peridot/packages/buildbot"]`
-
-From //root_build_dir/args.gn:2
-
-**Overridden from the default:** `[]`
-
-From [//build/gn/packages.gni:30](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/gn/packages.gni#30)
-
-**Current value for `target_cpu = "x64"`:** `["peridot/packages/buildbot"]`
-
-From //root_build_dir/args.gn:2
-
-**Overridden from the default:** `[]`
-
-From [//build/gn/packages.gni:30](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/gn/packages.gni#30)
-
-### glm_build_root
-
-**Current value (from the default):** `"//third_party/glm"`
-
-From [//garnet/lib/magma/gnbuild/magma.gni:9](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/magma/gnbuild/magma.gni#9)
-
-### ledger_sync_credentials_file
-
-**Current value (from the default):** `""`
-
-From [//peridot/bin/ledger/testing/sync_params.gni:6](https://fuchsia.googlesource.com/peridot/+/a71ce5bf32a5e55f13574d8ee289b28729891474/bin/ledger/testing/sync_params.gni#6)
-
-### target_cpu
-
-**Current value for `target_cpu = "arm64"`:** `"arm64"`
-
-From //root_build_dir/args.gn:1
-
-**Overridden from the default:** `""`
-
-**Current value for `target_cpu = "x64"`:** `"x64"`
-
-From //root_build_dir/args.gn:1
-
-**Overridden from the default:** `""`
-
-### build_libvulkan
-This is a list of targets that will be built as vulkan ICDS. If more than one
-target is given then use_vulkan_loader_for_tests must be set to true, as
-otherwise tests won't know which libvulkan to use.
-
-**Current value (from the default):** `[]`
-
-From [//garnet/lib/magma/gnbuild/magma.gni:38](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/magma/gnbuild/magma.gni#38)
-
-### build_msd_arm_mali
-
-**Current value (from the default):** `true`
-
-From [//garnet/lib/magma/gnbuild/magma.gni:21](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/magma/gnbuild/magma.gni#21)
-
-### enable_input_subsystem
-
-**Current value (from the default):** `true`
-
-From [//garnet/bin/ui/scenic/BUILD.gn:14](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/bin/ui/scenic/BUILD.gn#14)
+From [//build/images/zedboot/BUILD.gn:24](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/zedboot/BUILD.gn#24)
 
 ### zircon_boot_groups
 Groups to include from the Zircon /boot manifest into /boot.
@@ -542,167 +940,98 @@
 
 From [//build/images/BUILD.gn:25](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#25)
 
-### crashpad_dependencies
-Determines various flavors of build configuration, and which concrete
-targets to use for dependencies. Valid values are "standalone",
-"chromium", and "fuchsia". Defaulted to "fuchsia" because
-"is_fuchsia_tree" is set.
+### amber_keys_dir
+Directory containing signing keys used by amber-publish.
+
+**Current value (from the default):** `"//garnet/go/src/amber/keys"`
+
+From [//garnet/go/src/amber/amber.gni:14](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/go/src/amber/amber.gni#14)
+
+### host_os
+
+**Current value (from the default):** `"linux"`
+
+### enable_input_subsystem
+
+**Current value (from the default):** `true`
+
+From [//garnet/bin/ui/scenic/BUILD.gn:14](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/bin/ui/scenic/BUILD.gn#14)
+
+### glm_build_root
+
+**Current value (from the default):** `"//third_party/glm"`
+
+From [//garnet/lib/magma/gnbuild/magma.gni:9](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/magma/gnbuild/magma.gni#9)
+
+### rust_toolchain_triple_suffix
+Sets the fuchsia toolchain target triple suffix (after arch)
 
 **Current value (from the default):** `"fuchsia"`
 
-From [//third_party/crashpad/build/crashpad_buildconfig.gni:26](https://chromium.googlesource.com/crashpad/crashpad/+/8d17d5b4cf33f225cc13c865e9e7499272a5de02/build/crashpad_buildconfig.gni#26)
+From [//build/rust/config.gni:23](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/rust/config.gni#23)
 
-### extra_variants
-Additional variant toolchain configs to support.
-This is just added to [`known_variants`](#known_variants).
+### rustc_prefix
+Sets a custom base directory for `rustc` and `cargo`.
+This can be used to test custom Rust toolchains.
 
-**Current value (from the default):** `[]`
+**Current value (from the default):** `"//buildtools/linux-x64/rust/bin"`
 
-From [//build/config/BUILDCONFIG.gn:393](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/BUILDCONFIG.gn#393)
+From [//build/rust/config.gni:17](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/rust/config.gni#17)
 
-### magma_build_root
+### zircon_build_abi_dir
+Zircon build directory for `target_cpu`, containing link-time `.so.abi`
+files that GN `deps` on [//zircon/public](https://fuchsia.googlesource.com/zircon/+/2b80ad3e9e48eff77a0cb4dade6f53a2095e4c18/public) libraries will link against.
+This should not be a sanitizer build.
 
-**Current value (from the default):** `"//garnet/lib/magma"`
+**Current value (from the default):** `"//out/build-zircon/build-arm64"`
 
-From [//garnet/lib/magma/gnbuild/magma.gni:6](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/magma/gnbuild/magma.gni#6)
+From [//build/config/fuchsia/zircon.gni:14](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/fuchsia/zircon.gni#14)
 
-### scenic_ignore_vsync
+### clang_prefix
 
-**Current value (from the default):** `false`
+**Current value (from the default):** `"../buildtools/linux-x64/clang/bin"`
 
-From [//garnet/lib/ui/gfx/BUILD.gn:16](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/ui/gfx/BUILD.gn#16)
+From [//build/config/clang/clang.gni:9](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/clang/clang.gni#9)
 
-### update_kernels
-List of kernel images to include in the update (OTA) package.
-If no list is provided, all built kernels are included. The names in the
-list are strings that must match the filename to be included in the update
-package.
+### enable_frame_pointers
+Controls whether the compiler emits full stack frames for function calls.
+This reduces performance but increases the ability to generate good
+stack traces, especially when we have bugs around unwind table generation.
+It applies only for Fuchsia targets (see below where it is unset).
 
-**Current value (from the default):** `[]`
-
-From [//build/images/BUILD.gn:367](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#367)
-
-### use_lto
-Use link time optimization (LTO).
-
-**Current value (from the default):** `false`
-
-From [//build/config/lto/config.gni:7](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/lto/config.gni#7)
-
-### zedboot_cmdline_args
-List of kernel command line arguments to bake into the Zedboot image.
-See [//zircon/docs/kernel_cmdline.md](https://fuchsia.googlesource.com/zircon/+/2b80ad3e9e48eff77a0cb4dade6f53a2095e4c18/docs/kernel_cmdline.md) and
-[`zedboot_devmgr_config`](#zedboot_devmgr_config).
-
-**Current value (from the default):** `[]`
-
-From [//build/images/zedboot/BUILD.gn:15](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/zedboot/BUILD.gn#15)
-
-### zircon_boot_manifests
-Manifest files describing files to go into the `/boot` filesystem.
-Can be either // source paths or absolute system paths.
-`zircon_boot_groups` controls which files are actually selected.
-
-Since Zircon manifest files are relative to a Zircon source directory
-rather than to the directory containing the manifest, these are assumed
-to reside in a build directory that's a direct subdirectory of the
-Zircon source directory and thus their contents can be taken as
-relative to `get_path_info(entry, "dir") + "/.."`.
-
-**Current value (from the default):** `["//out/build-zircon/build-arm64/bootfs.manifest"]`
-
-From [//build/images/manifest.gni:44](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/manifest.gni#44)
-
-### msd_intel_gen_build_root
-
-**Current value (from the default):** `"//garnet/drivers/gpu/msd-intel-gen"`
-
-From [//garnet/lib/magma/gnbuild/magma.gni:8](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/magma/gnbuild/magma.gni#8)
-
-### enable_gfx_subsystem
+TODO(ZX-2361): Theoretically unwind tables should be good enough so we can
+remove this option when the issues are addressed.
 
 **Current value (from the default):** `true`
 
-From [//garnet/bin/ui/scenic/BUILD.gn:12](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/bin/ui/scenic/BUILD.gn#12)
+From [//build/config/BUILD.gn:16](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/BUILD.gn#16)
 
-### enable_sketchy_subsystem
-
-**Current value (from the default):** `true`
-
-From [//garnet/bin/ui/scenic/BUILD.gn:13](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/bin/ui/scenic/BUILD.gn#13)
-
-### expat_build_root
-
-**Current value (from the default):** `"//third_party/expat"`
-
-From [//garnet/lib/magma/gnbuild/magma.gni:7](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/magma/gnbuild/magma.gni#7)
-
-### fuchsia_products
-List of product definition files describing the packages to build, and
-where they are to be installed in images and updates.
-
-A product definition file is a JSON file containing:
-monolith:
-  a list of packages included in OTA images, base system images, and the
-  distribution repository.
-preinstall:
-  a list of packages pre-installed on the system (also added to the
-  distribution repository)
-available:
-  a list of packages only added to the distribution repository)
-
-If a package is referenced in monolith and in preinstall, monolith takes
-priority, and the package will be added to OTA images as part of the
-verified boot set of static packages.
-
-If unset, layer will be guessed using //.jiri_manifest and
-//{layer}/products/default will be used.
+### kernel_cmdline_files
+Files containing additional kernel command line arguments to bake into
+the boot image.  The contents of these files (in order) come after any
+arguments directly in [`kernel_cmdline_args`](#kernel_cmdline_args).
+These can be GN `//` source pathnames or absolute system pathnames.
 
 **Current value (from the default):** `[]`
 
-From [//build/gn/packages.gni:25](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/gn/packages.gni#25)
+From [//build/images/BUILD.gn:355](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#355)
 
-### fvm_slice_size
-The size of the FVM partition images "slice size". The FVM slice size is a
-minimum size of a particular chunk of a partition that is stored within
-FVM. A very small slice size may lead to decreased throughput. A very large
-slice size may lead to wasted space. The selected default size of 8mb is
-selected for conservation of space, rather than performance.
+### synthesize_packages
+List of extra packages to synthesize on the fly.  This is only for
+things that do not appear normally in the source tree.  Synthesized
+packages can contain build artifacts only if they already exist in some
+part of the build.  They can contain arbitrary verbatim files.
+Synthesized packages can't express dependencies on other packages.
 
-**Current value (from the default):** `"8388608"`
-
-From [//build/images/BUILD.gn:581](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#581)
-
-### goma_dir
-Absolute directory containing the Goma source code.
-
-**Current value (from the default):** `"/home/swarming/goma"`
-
-From [//build/toolchain/goma.gni:12](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/toolchain/goma.gni#12)
-
-### magma_enable_developer_build
-Enable this to have the msd include a suite of tests and invoke them
-automatically when the driver starts.
-
-**Current value (from the default):** `false`
-
-From [//garnet/lib/magma/gnbuild/magma.gni:19](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/magma/gnbuild/magma.gni#19)
-
-### rust_lto
-Sets the default LTO type for rustc bulids.
-
-**Current value (from the default):** `"unset"`
-
-From [//build/rust/config.gni:20](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/rust/config.gni#20)
-
-### select_variant_canonical
-*This should never be set as a build argument.*
-It exists only to be set in `toolchain_args`.
-See [//build/toolchain/clang_toolchain.gni](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/toolchain/clang_toolchain.gni) for details.
+Each element of this list is a scope that is very much like the body of
+a package() template invocation (see [//build/package.gni](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/package.gni)).  That scope
+must set `name` to the string naming the package, as would be the name
+in the package() target written in a GN file.  This must be unique
+among all package names.
 
 **Current value (from the default):** `[]`
 
-From [//build/config/BUILDCONFIG.gn:618](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/BUILDCONFIG.gn#618)
+From [//build/gn/packages.gni:43](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/gn/packages.gni#43)
 
 ### zedboot_cmdline_files
 Files containing additional kernel command line arguments to bake into
@@ -727,25 +1056,14 @@
 
 From [//build/images/BUILD.gn:36](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#36)
 
-### dart_pool_depth
-Maximum number of Dart processes to run in parallel.
+### enable_crashpad
+When this is set, Crashpad will be used to handle exceptions (which uploads
+crashes to the crash server), rather than crashanalyzer in Zircon (which
+prints the crash log to the the system log).
 
-Dart analyzer uses a lot of memory which may cause issues when building
-with many parallel jobs e.g. when using goma. To avoid out-of-memory
-errors we explicitly reduce the number of jobs.
+**Current value (from the default):** `false`
 
-**Current value (from the default):** `16`
-
-From [//build/dart/toolchain.gni:11](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/dart/toolchain.gni#11)
-
-### data_image_size
-The size of the minfs data partition image to create. Normally this image
-is added to FVM, and can therefore expand as needed. It must be at least
-10mb (the default) in order to be succesfully initialized.
-
-**Current value (from the default):** `"10m"`
-
-From [//build/images/BUILD.gn:568](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#568)
+From [//build/images/crashpad.gni:9](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/crashpad.gni#9)
 
 ### host_tools_dir
 This is the directory where host tools intended for manual use by
@@ -760,326 +1078,17 @@
 
 From [//build/host.gni:13](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/host.gni#13)
 
-### use_thinlto
-Use ThinLTO variant of LTO if use_lto = true.
-
-**Current value (from the default):** `true`
-
-From [//build/config/lto/config.gni:10](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/lto/config.gni#10)
-
-### vk_loader_debug
-
-**Current value (from the default):** `"warn,error"`
-
-From [//third_party/vulkan_loader_and_validation_layers/loader/BUILD.gn:26](https://fuchsia.googlesource.com/third_party/vulkan_loader_and_validation_layers/+/3106666ca09bdab1a0f3c4c5d4d614bf4dab1f3d/loader/BUILD.gn#26)
-
-### zedboot_devmgr_config
-List of arguments to populate /boot/config/devmgr in the Zedboot image.
-
-**Current value (from the default):** `["netsvc.netboot=true"]`
-
-From [//build/images/zedboot/BUILD.gn:24](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/zedboot/BUILD.gn#24)
-
-### zircon_build_abi_dir
-Zircon build directory for `target_cpu`, containing link-time `.so.abi`
-files that GN `deps` on [//zircon/public](https://fuchsia.googlesource.com/zircon/+/2b80ad3e9e48eff77a0cb4dade6f53a2095e4c18/public) libraries will link against.
-This should not be a sanitizer build.
-
-**Current value (from the default):** `"//out/build-zircon/build-arm64"`
-
-From [//build/config/fuchsia/zircon.gni:14](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/fuchsia/zircon.gni#14)
-
-### thinlto_cache_dir
-ThinLTO cache directory path.
-
-**Current value (from the default):** `"host_x64/thinlto-cache"`
-
-From [//build/config/lto/config.gni:16](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/lto/config.gni#16)
-
-### amber_repository_dir
-Directory containing files named by their merkleroot content IDs in
-ASCII hex.  The [//build/image](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/image):amber_publish_blobs target populates
-this with copies of build products, but never removes old files.
-
-**Current value (from the default):** `"//root_build_dir/amber-files"`
-
-From [//garnet/go/src/amber/amber.gni:11](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/go/src/amber/amber.gni#11)
-
-### clang_prefix
-
-**Current value (from the default):** `"../buildtools/linux-x64/clang/bin"`
-
-From [//build/config/clang/clang.gni:9](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/clang/clang.gni#9)
-
-### enable_crashpad
-When this is set, Crashpad will be used to handle exceptions (which uploads
-crashes to the crash server), rather than crashanalyzer in Zircon (which
-prints the crash log to the the system log).
-
-**Current value (from the default):** `false`
-
-From [//build/images/crashpad.gni:9](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/crashpad.gni#9)
-
-### is_debug
-Debug build.
-
-**Current value (from the default):** `true`
-
-From [//build/config/BUILDCONFIG.gn:11](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/BUILDCONFIG.gn#11)
-
-### sdk_dirs
-The directories to search for parts of the SDK.
-
-By default, we search the public directories for the various layers.
-In the future, we'll search a pre-built SDK as well.
-
-**Current value (from the default):** `["//garnet/public", "//peridot/public", "//topaz/public"]`
-
-From [//build/config/fuchsia/sdk.gni:10](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/fuchsia/sdk.gni#10)
-
-### select_variant_shortcuts
-List of short names for commonly-used variant selectors.  Normally this
-is not set as a build argument, but it serves to document the available
-set of short-cut names for variant selectors.  Each element of this list
-is a scope where `.name` is the short name and `.select_variant` is a
-a list that can be spliced into [`select_variant`](#select_variant).
-
-**Current value (from the default):**
-```
-[{
-  name = "host_asan"
-  select_variant = [{
-  dir = ["//third_party/yasm", "//third_party/vboot_reference", "//garnet/tools/vboot_reference"]
-  host = true
-  variant = "asan_no_detect_leaks"
-}, {
-  host = true
-  variant = "asan"
-}]
-}, {
-  name = "asan"
-  select_variant = [{
-  target_type = ["driver_module"]
-  variant = false
-}, {
-  host = false
-  variant = "asan"
-}]
-}]
-```
-
-From [//build/config/BUILDCONFIG.gn:439](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/BUILDCONFIG.gn#439)
-
-### synthesize_packages
-List of extra packages to synthesize on the fly.  This is only for
-things that do not appear normally in the source tree.  Synthesized
-packages can contain build artifacts only if they already exist in some
-part of the build.  They can contain arbitrary verbatim files.
-Synthesized packages can't express dependencies on other packages.
-
-Each element of this list is a scope that is very much like the body of
-a package() template invocation (see [//build/package.gni](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/package.gni)).  That scope
-must set `name` to the string naming the package, as would be the name
-in the package() target written in a GN file.  This must be unique
-among all package names.
-
-**Current value (from the default):** `[]`
-
-From [//build/gn/packages.gni:43](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/gn/packages.gni#43)
-
-### toolchain_manifests
-Manifest files describing target libraries from toolchains.
-Can be either // source paths or absolute system paths.
-
-**Current value (from the default):** `["/b/s/w/ir/kitchen-workdir/buildtools/linux-x64/clang/lib/x86_64-linux.manifest"]`
-
-From [//build/images/manifest.gni:11](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/manifest.gni#11)
-
-### scenic_vulkan_swapchain
-
-**Current value (from the default):** `1`
-
-From [//garnet/lib/ui/gfx/BUILD.gn:12](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/ui/gfx/BUILD.gn#12)
-
-### always_zedboot
-Build boot images that prefer Zedboot over local boot (only for EFI).
-
-**Current value (from the default):** `false`
-
-From [//build/images/BUILD.gn:584](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#584)
-
-### amlogic_decoder_tests
-
-**Current value (from the default):** `false`
-
-From [//garnet/drivers/video/amlogic-decoder/BUILD.gn:10](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/drivers/video/amlogic-decoder/BUILD.gn#10)
-
-### cloudkms_key_dir
-
-**Current value (from the default):** `"projects/fuchsia-infra/locations/global/keyRings/test-secrets/cryptoKeys"`
-
-From [//build/testing/secret_spec.gni:8](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/testing/secret_spec.gni#8)
-
-### enable_frame_pointers
-Controls whether the compiler emits full stack frames for function calls.
-This reduces performance but increases the ability to generate good
-stack traces, especially when we have bugs around unwind table generation.
-It applies only for Fuchsia targets (see below where it is unset).
-
-TODO(ZX-2361): Theoretically unwind tables should be good enough so we can
-remove this option when the issues are addressed.
-
-**Current value (from the default):** `true`
-
-From [//build/config/BUILD.gn:16](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/BUILD.gn#16)
-
-### fvm_image_size
-The size in bytes of the FVM partition image to create. Normally this is
-computed to be just large enough to fit the blob and data images. The
-default value is "", which means to size based on inputs. Specifying a size
-that is too small will result in build failure.
-
-**Current value (from the default):** `""`
-
-From [//build/images/BUILD.gn:574](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#574)
-
-### host_byteorder
-
-**Current value (from the default):** `"undefined"`
-
-From [//build/config/host_byteorder.gni:7](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/host_byteorder.gni#7)
-
-### magma_python_path
-
-**Current value (from the default):** `"/b/s/w/ir/kitchen-workdir/third_party/mako"`
-
-From [//garnet/lib/magma/gnbuild/magma.gni:12](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/magma/gnbuild/magma.gni#12)
-
-### zircon_tools_dir
-Where to find Zircon's host-side tools that are run as part of the build.
-
-**Current value (from the default):** `"//out/build-zircon/tools"`
-
-From [//build/config/fuchsia/zircon.gni:9](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/fuchsia/zircon.gni#9)
-
-### zircon_use_asan
-Set this if [`zircon_build_dir`](#zircon_build_dir) was built with
-`USE_ASAN=true`, e.g. `[//scripts/build-zircon.sh](https://fuchsia.googlesource.com/scripts/+/c04e34ca6e090f0c5c9734fbf9dde8d93df8490d/build-zircon.sh) -A`.  This mainly
-affects the defaults for [`zircon_build_dir`](#zircon_build_dir) and
-[`zircon_build_abi_dir`](#zircon_build_abi_dir).  It also gets noticed
-by [//scripts/fx](https://fuchsia.googlesource.com/scripts/+/c04e34ca6e090f0c5c9734fbf9dde8d93df8490d/fx) commands that rebuild Zircon so that they use `-A`
-again next time.
-
-**Current value (from the default):** `false`
-
-From [//build/config/fuchsia/zircon.gni:40](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/fuchsia/zircon.gni#40)
-
-### devmgr_config
-List of arguments to add to /boot/config/devmgr.
-These come after synthesized arguments to configure blobfs and pkgfs,
-and the one generated for [`enable_crashpad`](#enable_crashpad).
-
-**Current value (from the default):** `[]`
-
-From [//build/images/BUILD.gn:344](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/images/BUILD.gn#344)
-
-### extra_authorized_keys_file
-Additional SSH authorized_keys file to include in the build.
-For example:
-  extra_authorized_keys_file=\"$HOME/.ssh/id_rsa.pub\"
-
-**Current value (from the default):** `""`
-
-From [//third_party/openssh-portable/fuchsia/developer-keys/BUILD.gn:11](https://fuchsia.googlesource.com/third_party/openssh-portable/+/baf903a4aff34287c9571060a961a836e6fec75f/fuchsia/developer-keys/BUILD.gn#11)
-
-### zircon_asserts
-
-**Current value (from the default):** `true`
-
-From [//build/config/fuchsia/BUILD.gn:138](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/fuchsia/BUILD.gn#138)
-
-### build_sdk_archives
-Whether to build SDK tarballs.
-
-**Current value (from the default):** `false`
-
-From [//build/sdk/sdk.gni:11](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/sdk/sdk.gni#11)
-
-### scudo_default_options
-Default [Scudo](https://llvm.org/docs/ScudoHardenedAllocator.html)
-options (before the `SCUDO_OPTIONS` environment variable is read at
-runtime).  *NOTE:* This affects only components using the `scudo`
-variant (see GN build argument `select_variant`), and does not affect
-anything when the `use_scudo` build flag is set instead.
-
-**Current value (from the default):** `["abort_on_error=1", "QuarantineSizeKb=0", "ThreadLocalQuarantineSizeKb=0", "DeallocationTypeMismatch=false", "DeleteSizeMismatch=false", "allocator_may_return_null=true"]`
-
-From [//build/config/scudo/scudo.gni:15](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/scudo/scudo.gni#15)
-
-### target_os
-
-**Current value (from the default):** `""`
-
-### universal_variants
-
-**Current value (from the default):**
-```
-[{
-  configs = []
-  name = "release"
-  toolchain_args = {
-  is_debug = false
-}
-}]
-```
-
-From [//build/config/BUILDCONFIG.gn:413](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/BUILDCONFIG.gn#413)
-
-### use_vulkan_loader_for_tests
-Mesa doesn't properly handle loader-less operation;
-their GetInstanceProcAddr implementation returns 0 for some interfaces.
-On ARM there may be multiple libvulkan_arms, so they can't all be linked
-to.
-
-**Current value (from the default):** `true`
-
-From [//garnet/lib/magma/gnbuild/magma.gni:33](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/magma/gnbuild/magma.gni#33)
-
-### crashpad_use_boringssl_for_http_transport_socket
-
-**Current value (from the default):** `false`
-
-From [//third_party/crashpad/util/net/tls.gni:18](https://chromium.googlesource.com/crashpad/crashpad/+/8d17d5b4cf33f225cc13c865e9e7499272a5de02/util/net/tls.gni#18)
-
-### prebuilt_libvulkan_arm_path
-
-**Current value (from the default):** `""`
-
-From [//garnet/lib/magma/gnbuild/magma.gni:25](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/magma/gnbuild/magma.gni#25)
-
-### rust_toolchain_triple_suffix
-Sets the fuchsia toolchain target triple suffix (after arch)
-
-**Current value (from the default):** `"fuchsia"`
-
-From [//build/rust/config.gni:23](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/rust/config.gni#23)
-
-### zircon_build_dir
-Zircon build directory for `target_cpu`, containing `.manifest` and
-`.zbi` files for Zircon's BOOTFS and kernel.  This provides the kernel
-and Zircon components used in the boot image.  It also provides the
-Zircon shared libraries used at runtime in Fuchsia packages.
-
-If left `""` (the default), then this is computed from
-[`zircon_build_abi_dir`](#zircon_build_abi_dir) and
-[`zircon_use_asan`](#zircon_use_asan).
-
-**Current value (from the default):** `""`
-
-From [//build/config/fuchsia/zircon.gni:24](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/fuchsia/zircon.gni#24)
-
 ## `target_cpu = "arm64"`
 
+### arm_tune
+The ARM variant-specific tuning mode. This will be a string like "armv6"
+or "cortex-a15". An empty string means to use the default for the
+arm_version.
+
+**Current value (from the default):** `""`
+
+From [//build/config/arm.gni:25](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/arm.gni#25)
+
 ### arm_use_neon
 Whether to use the neon FPU instruction set or not.
 
@@ -1098,7 +1107,7 @@
 
 **Current value (from the default):** `true`
 
-From [//garnet/drivers/gpu/msd-arm-mali/src/BUILD.gn:9](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/drivers/gpu/msd-arm-mali/src/BUILD.gn#9)
+From [//garnet/drivers/gpu/msd-arm-mali/src/BUILD.gn:9](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/drivers/gpu/msd-arm-mali/src/BUILD.gn#9)
 
 ### msd_arm_enable_cache_coherency
 With this flag set the system tries to use cache coherent memory if the
@@ -1106,7 +1115,7 @@
 
 **Current value (from the default):** `true`
 
-From [//garnet/drivers/gpu/msd-arm-mali/src/BUILD.gn:13](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/drivers/gpu/msd-arm-mali/src/BUILD.gn#13)
+From [//garnet/drivers/gpu/msd-arm-mali/src/BUILD.gn:13](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/drivers/gpu/msd-arm-mali/src/BUILD.gn#13)
 
 ### arm_float_abi
 The ARM floating point mode. This is either the string "hard", "soft", or
@@ -1124,28 +1133,19 @@
 
 From [//build/config/arm.gni:31](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/arm.gni#31)
 
-### arm_tune
-The ARM variant-specific tuning mode. This will be a string like "armv6"
-or "cortex-a15". An empty string means to use the default for the
-arm_version.
-
-**Current value (from the default):** `""`
-
-From [//build/config/arm.gni:25](https://fuchsia.googlesource.com/build/+/2d263d047e44c996c64e6aef44a1b0afea32eaa1/config/arm.gni#25)
-
 ## `target_cpu = "x64"`
 
 ### mesa_build_root
 
 **Current value (from the default):** `"//third_party/mesa"`
 
-From [//garnet/lib/magma/gnbuild/magma.gni:41](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/lib/magma/gnbuild/magma.gni#41)
+From [//garnet/lib/magma/gnbuild/magma.gni:41](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/lib/magma/gnbuild/magma.gni#41)
 
 ### msd_intel_enable_mapping_cache
 
 **Current value (from the default):** `false`
 
-From [//garnet/drivers/gpu/msd-intel-gen/src/BUILD.gn:8](https://fuchsia.googlesource.com/garnet/+/b825b2a5cc192deaa9bcb3c93f4e2da2463e0749/drivers/gpu/msd-intel-gen/src/BUILD.gn#8)
+From [//garnet/drivers/gpu/msd-intel-gen/src/BUILD.gn:8](https://fuchsia.googlesource.com/garnet/+/3ecad1a69f73a13d46591a33e05e8c8092b52686/drivers/gpu/msd-intel-gen/src/BUILD.gn#8)
 
 ### use_mock_magma