[devhost] Enable compiling in driver tracing by default
Users still have to pass the following on the kernel command line
in order for drivers to be traced: driver.tracing.enable=1
ZX-2876 #comment patch
Tested: Verify driver tracing support is present, CQ
Change-Id: Ifa21af22a554101b21a5a169f66107e62a656d42
diff --git a/docs/ddk/tracing.md b/docs/ddk/tracing.md
index ebe62ad..3836ac9 100644
--- a/docs/ddk/tracing.md
+++ b/docs/ddk/tracing.md
@@ -87,12 +87,15 @@
it also requires an extra kernel command line flag to enable it:
`driver.tracing.enable=1`
+`ENABLE_DRIVER_TRACING=true` is now the default. To disable driver tracing,
+pass `ENABLE_DRIVER_TRACING=false` to make.
+
Example:
-First build with driver tracing enabled:
+First build:
```sh
-$ fx set $arch --zircon-arg ENABLE_DRIVER_TRACING=true
+$ fx set $arch
$ fx build-zircon
$ fx build
```
diff --git a/make/engine.mk b/make/engine.mk
index 00f41c4..3e88829 100644
--- a/make/engine.mk
+++ b/make/engine.mk
@@ -29,6 +29,8 @@
ENABLE_LOCK_DEP_TESTS ?= $(ENABLE_LOCK_DEP)
DISABLE_UTEST ?= false
ENABLE_ULIB_ONLY ?= false
+ENABLE_DRIVER_TRACING ?= true
+ENABLE_DRIVER_TRACING := $(call TOBOOL,$(ENABLE_DRIVER_TRACING))
USE_ASAN ?= false
USE_SANCOV ?= false
USE_PROFILE ?= false
