Allow the use of a custom Android DT directory
On platforms that use ACPI instead of Device Tree (DT), such as
Ranchu x86/x86_64, /proc/device-tree/firmware/android/ does not
exist. As a result, Android O is unable to mount /system, etc.
at the first stage of init:
init: First stage mount skipped (missing/incompatible fstab in
device tree)
Those platforms may create another directory that mimics the layout
of the standard DT directory in procfs, and store early mount
configuration there. E.g., Ranchu x86/x86_64 creates one in sysfs
using information encoded in the ACPI tables:
https://android-review.googlesource.com/442472
https://android-review.googlesource.com/443432
https://android-review.googlesource.com/442393
https://android-review.googlesource.com/442395
Therefore, instead of hardcoding the Android DT path, load it from
the kernel command line using a new Android-specific property key
("androidboot.android_dt_dir"). If no such property exists, fall
back to the standard procfs path (so no change is needed for DT-
aware platforms).
Note that init/ and fs_mgr/ each have their own copy of the Android
DT path, because they do not share any global state. A future CL
should remove the duplication by refactoring.
With this CL as well as the above ones, the said warning is gone,
but early mount fails. That is a separate bug, though, and will be
addressed by another CL.
Test: Boot patched sdk_phone_x86-userdebug system image with patched
Goldfish 3.18 x86 kernel in patched Android Emulator, verify
the "init: First stage mount skipped" warning no longer shows
in dmesg.
Change-Id: Ib6df577319503ec1ca778de2b5458cc72ce07415
Signed-off-by: Yu Ning <yu.ning@intel.com>
7 files changed