sdk/fidl/zbi/zbi.fidl

// Copyright 2023 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

library zbi;

// TODO(https://fxbug.dev/42062786): Figure out documentation convention.

const ALIGNMENT uint32 = 8;

/// Numeric prefix for kernel types.
///
/// 'KRN\0'
const TYPE_KERNEL_PREFIX uint32 = 0x004e524b;

/// Mask to compare against TYPE_KERNEL_PREFIX.
const TYPE_KERNEL_MASK uint32 = 0x00ffffff;

/// Numeric prefix for driver metadata types.
///
/// 'm\0\0\0'
const TYPE_DRIVER_METADATA_PREFIX uint32 = 0x0000006d;

/// Mask to compare against TYPE_DRIVER_METADATA_PREFIX.
const TYPE_DRIVER_METADATA_MASK uint32 = 0x000000ff;

type Type = flexible enum : uint32 {

    /// 'BOOT'
    ///
    /// Each ZBI starts with a container header.
    ///     length:          Total size of the image after this header.
    ///                      This includes all item headers, payloads, and padding.
    ///                      It does not include the container header itself.
    ///                      Must be a multiple of ZBI_ALIGNMENT.
    ///     extra:           Must be ZBI_CONTAINER_MAGIC.
    ///     flags:           Must be ZBI_FLAGS_VERSION and no other flags.
    CONTAINER = 0x544f4f42;

    /// x86-64 kernel. See zbi_kernel_t for a payload description.
    ///
    /// 'KRNL'
    KERNEL_X64 = 0x4c000000 | TYPE_KERNEL_PREFIX;

    /// ARM64 kernel. See zbi_kernel_t for a payload description.
    ///
    /// KRN8
    KERNEL_ARM64 = 0x38000000 | TYPE_KERNEL_PREFIX;

    /// RISC-V kernel. See zbi_kernel_t for a payload description.
    ///
    /// 'KRNV'
    KERNEL_RISCV64 = 0x56000000 | TYPE_KERNEL_PREFIX;

    /// A discarded item that should just be ignored.  This is used for an
    /// item that was already processed and should be ignored by whatever
    /// stage is now looking at the ZBI.  An earlier stage already "consumed"
    /// this information, but avoided copying data around to remove it from
    /// the ZBI item stream.
    ///
    /// 'SKIP'
    DISCARD = 0x50494b53;

    /// A virtual disk image.  This is meant to be treated as if it were a
    /// storage device.  The payload (after decompression) is the contents of
    /// the storage device, in whatever format that might be.
    ///
    /// 'RDSK'
    STORAGE_RAMDISK = 0x4b534452;

    /// The /boot filesystem in BOOTFS format, specified in
    /// <lib/zbi-format/internal/bootfs.h>.  This represents an internal
    /// contract between Zircon userboot (//docs/userboot.md), which handles
    /// the contents of this filesystem, and platform tooling, which prepares
    /// them.
    ///
    /// 'BFSB'
    STORAGE_BOOTFS = 0x42534642;

    /// Storage used by the kernel (such as a compressed image containing the
    /// actual kernel).  The meaning and format of the data is specific to the
    /// kernel, though it always uses the standard (private) storage
    /// compression protocol. Each particular KERNEL_{ARCH} item image and its
    /// STORAGE_KERNEL item image are intimately tied and one cannot work
    /// without the exact correct corresponding other.
    ///
    /// 'KSTR'
    STORAGE_KERNEL = 0x5254534b;

    // The remaining types are used to communicate information from the boot
    // loader to the kernel.  Usually these are synthesized in memory by the
    // boot loader, but they can also be included in a ZBI along with the
    // kernel and BOOTFS.  Some boot loaders may set the zbi_header_t flags
    // and crc32 fields to zero, though setting them to ZBI_FLAGS_VERSION and
    // ZBI_ITEM_NO_CRC32 is specified.  The kernel doesn't check.

    /// Device-specific factory data, stored in BOOTFS format.
    ///
    /// TODO(https://fxbug.dev/42109921): This should not use the "STORAGE" infix.
    ///
    /// 'BFSF'
    STORAGE_BOOTFS_FACTORY = 0x46534642;

    /// A kernel command line fragment, a UTF-8 string that need not be
    /// NUL-terminated.  The kernel's own option parsing accepts only printable
    /// 'ASCI'I and treats all other characters as equivalent to whitespace. Multiple
    /// ZBI_TYPE_CMDLINE items can appear.  They are treated as if concatenated with
    /// ' ' between each item, in the order they appear: first items in the bootable
    /// ZBI containing the kernel; then items in the ZBI synthesized by the boot
    /// loader.  The kernel interprets the [whole command line](../../../../docs/kernel_cmdline.md).
    ///
    /// 'CMDL'
    CMDLINE = 0x4c444d43;

    /// The crash log from the previous boot, a UTF-8 string.
    ///
    /// 'BOOM'
    CRASHLOG = 0x4d4f4f42;

    /// Physical memory region that will persist across warm boots. See zbi_nvram_t
    /// for payload description.
    ///
    /// 'NVLL'
    NVRAM = 0x4c4c564e;

    /// Platform ID Information.
    ///
    /// 'PLID'
    PLATFORM_ID = 0x44494c50;

    /// Board-specific information.
    ///
    /// mBSI
    DRV_BOARD_INFO = 0x49534200 | TYPE_DRIVER_METADATA_PREFIX;

    /// CPU configuration. See zbi_topology_node_t for a description of the payload.
    //
    // 'CPU3'
    CPU_TOPOLOGY = 0x43505533;

    /// Device memory configuration. See zbi_mem_range_t for a description of the
    /// payload.
    ///
    /// 'MEMC'
    MEM_CONFIG = 0x434d454d;

    /// Kernel driver configuration.  The zbi_header_t.extra field gives a
    /// ZBI_KERNEL_DRIVER_* type that determines the payload format.
    /// See <lib/zbi-format/driver-config.h> for details.
    ///
    /// 'KDRV'
    KERNEL_DRIVER = 0x5652444b;

    /// 'ACPI' Root Table Pointer, a uint64_t physical address.
    ///
    /// 'RSDP'
    ACPI_RSDP = 0x50445352;

    /// 'SMBI'
    ///
    /// 'SMBI'OS entry point, a uint64_t physical address.
    SMBIOS = 0x49424d53;

    /// EFI system table, a uint64_t physical address.
    ///
    /// 'EFIS'
    EFI_SYSTEM_TABLE = 0x53494645;

    /// EFI memory attributes table. An example of this format can be found in UEFI 2.10 section 4.6.4,
    /// but the consumer of this item is responsible for interpreting whatever the bootloader supplies
    /// (in particular the "version" field may differ as the format evolves).
    ///
    /// 'EMAT'
    EFI_MEMORY_ATTRIBUTES_TABLE = 0x54414d45;

    /// Framebuffer parameters, a zbi_swfb_t entry.
    ///
    /// 'SWFB'
    FRAMEBUFFER = 0x42465753;

    /// The image arguments, data is a trivial text format of one "key=value" per line
    /// with leading whitespace stripped and "#" comment lines and blank lines ignored.
    /// It is processed by bootsvc and parsed args are shared to others via Arguments service.
    /// TODO: the format can be streamlined after the /config/additional_boot_args compat support is
    /// removed.
    ///
    /// 'IARG'
    IMAGE_ARGS = 0x47524149;

    /// A copy of the boot version stored within the sysconfig
    /// partition
    ///
    /// 'BVRS'
    BOOT_VERSION = 0x53525642;

    /// MAC address for Ethernet, Wifi, Bluetooth, etc.  zbi_header_t.extra
    /// is a board-specific index to specify which device the MAC address
    /// applies to.  zbi_header_t.length gives the size in bytes, which
    /// varies depending on the type of address appropriate for the device.
    ///
    /// mMAC
    DRV_MAC_ADDRESS = 0x43414d00 | TYPE_DRIVER_METADATA_PREFIX;

    /// A partition map for a storage device, a zbi_partition_map_t header
    /// followed by one or more zbi_partition_t entries.  zbi_header_t.extra
    /// is a board-specific index to specify which device this applies to.
    ///
    /// mPRT
    DRV_PARTITION_MAP = 0x54525000 | TYPE_DRIVER_METADATA_PREFIX;

    /// Private information for the board driver.
    ///
    /// mBOR
    DRV_BOARD_PRIVATE = 0x524f4200 | TYPE_DRIVER_METADATA_PREFIX;

    /// 'HWRB'
    HW_REBOOT_REASON = 0x42525748;

    /// The serial number, an unterminated ASCII string of printable non-whitespace
    /// characters with length zbi_header_t.length.
    ///
    /// 'SRLN'
    SERIAL_NUMBER = 0x4e4c5253;

    /// This type specifies a binary file passed in by the bootloader.
    /// The first byte specifies the length of the filename without a NUL terminator.
    /// The filename starts on the second byte.
    /// The file contents are located immediately after the filename.
    ///
    /// Layout: | name_len |        name       |   payload
    ///           ^(1 byte)  ^(name_len bytes)     ^(length of file)
    ///
    /// 'BTFL'
    BOOTLOADER_FILE = 0x4c465442;

    /// The devicetree blob from the legacy boot loader, if any.  This is used only
    /// for diagnostic and development purposes.  Zircon kernel and driver
    /// configuration is entirely driven by specific ZBI items from the boot
    /// loader.  The boot shims for legacy boot loaders pass the raw devicetree
    /// along for development purposes, but extract information from it to populate
    /// specific ZBI items such as ZBI_TYPE_KERNEL_DRIVER et al.
    DEVICETREE = 0xd00dfeed;

    /// An arbitrary number of random bytes attested to have high entropy.  Any
    /// number of items of any size can be provided, but no data should be provided
    /// that is not true entropy of cryptographic quality.  This is used to seed
    /// secure cryptographic pseudo-random number generators.
    ///
    /// 'RAND'
    SECURE_ENTROPY = 0x444e4152;

    /// This provides a data dump and associated logging from a boot loader,
    /// shim, or earlier incarnation that wants its data percolated up by the
    /// booting Zircon kernel. See zbi_debugdata_t for a description of the
    /// payload.
    ///
    /// 'DBGD'
    DEBUGDATA = 0x44474244;

    /// Each RISC-V hart has an associated "ISA string" encoding its supported
    /// extensions: see Chapter 27 (ISA Extension Naming Conventions) in
    /// https://riscv.org/wp-content/uploads/2019/12/riscv-spec-20191213.pdf.
    /// This item gives the NUL-separated (and -terminated) concatenation of
    /// all such strings in the system.
    ///
    /// The first character of the table must be NUL; that is, the first entry
    /// in the table must be the empty and invalid, which is pointed to by a
    /// default-constructructed index. Beyond that, there are no guarantees to
    /// order the strings in the table or the extent of their (de)duplication.
    ///
    /// A given hart's index into the table is encoded within its associated
    /// node structure in the ZBI_TYPE_CPU_TOPOLOGY item.
    ///
    /// 'VISA'
    RISCV64_ISA_STRTAB = 0x41534956;
};

/// LSW of sha256("bootdata")
const CONTAINER_MAGIC uint32 = 0x868cf7e6;

/// LSW of sha256("bootitem")
const ITEM_MAGIC uint32 = 0xb5781729;

/// Flags associated with an item.  A valid flags value must always include
/// ZBI_FLAGS_VERSION. Values should also contain ZBI_FLAGS_CRC32 for any item
/// where it's feasible to compute the CRC32 at build time.  Other flags are
/// specific to each type.
type Flags = flexible bits : uint32 {
    // 0x00000001 is reserved for internal usage.

    /// This flag is always required.
    VERSION = 0x00010000;

    /// ZBI items with the CRC32 flag must have a valid crc32.
    /// Otherwise their crc32 field must contain ZBI_ITEM_NO_CRC32
    CRC32 = 0x00020000;
};

/// Value for zbi_header_t.crc32 when ZBI_FLAGS_CRC32 is not set.
const ITEM_NO_CRC32 uint32 = 0x4a87e8d6;

/// Each header must be 8-byte aligned.  The length field specifies the
/// actual payload length and does not include the size of padding.
type Header = struct {
    /// ZBI_TYPE_* constant.
    type Type;

    /// Size of the payload immediately following this header.  This
    /// does not include the header itself nor any alignment padding
    /// after the payload.
    length uint32;

    /// Type-specific extra data.  Each type specifies the use of this
    /// field.  When not explicitly specified, it should be zero.
    extra uint32;

    /// Flags for this item.
    flags Flags;

    /// For future expansion.  Set to 0.
    reserved0 uint32;
    reserved1 uint32;

    /// Must be ZBI_ITEM_MAGIC.
    magic uint32;

    /// Must be the CRC32 of payload if ZBI_FLAGS_CRC32 is set,
    /// otherwise must be ZBI_ITEM_NO_CRC32.
    crc32 uint32;
};