Mount system and vendor over dm-verity
This CL fixes a series of mistakes which let the system and the vendor
partition be mounted without dm-verity.
* avb=vbmeta and avb=vbmeta_system flags are added to fstab so that the
partitions are mounted over dm-verity
* uboot script is modified to append avb_bootargs into bootargs so that
avb parameters like the root hash, etc. are passed to the kernel via
cmdline
* The boot partition is no longer a chained partition. Its hashtree is
included in vbmeta.img directly. This is firstly because we don't have a
need to update the kernel independently from other partitions. And
secondly, boot as a chained partition requires us to create
/dev/block/by-name/boot during the first stage init, which require
additional-but-useless entry in fstab.
* Name of the logical partitions in super.img is changed to system_a and
vendor_a from system and vendor, respectively.
Bug: 198303625
Test: boot microdroid. `ls /dev/block/mapper` shows
```
drwxr-xr-x 3 root root 160 2021-09-01 03:10 .
drwxr-xr-x 5 root root 1180 2021-09-01 03:10 ..
drwxr-xr-x 2 root root 140 2021-09-01 03:10 by-uuid
lrwxrwxrwx 1 root root 15 2021-09-01 03:10 microdroid-apk -> /dev/block/dm-4
lrwxrwxrwx 1 root root 15 2021-09-01 03:10 system-verity -> /dev/block/dm-2
lrwxrwxrwx 1 root root 15 2021-09-01 03:10 system_a -> /dev/block/dm-0
lrwxrwxrwx 1 root root 15 2021-09-01 03:10 vendor-verity -> /dev/block/dm-3
lrwxrwxrwx 1 root root 15 2021-09-01 03:10 vendor_a -> /dev/block/dm-1
```
Change-Id: I6b485d841d9bd774ab964fd9ae7d2e0a15795b14
diff --git a/microdroid/fstab.microdroid b/microdroid/fstab.microdroid
index 129718e..f0e70b6 100644
--- a/microdroid/fstab.microdroid
+++ b/microdroid/fstab.microdroid
@@ -1,2 +1,2 @@
-system /system ext4 noatime,ro,errors=panic wait,first_stage_mount,logical
-vendor /vendor ext4 noatime,ro,errors=panic wait,first_stage_mount,logical
+system /system ext4 noatime,ro,errors=panic wait,slotselect,avb=vbmeta_system,first_stage_mount,logical
+vendor /vendor ext4 noatime,ro,errors=panic wait,slotselect,avb=vbmeta,first_stage_mount,logical