GSI

This document introduces special GSI settings for facilitating xTS-on-GSI with a single image.

Support system_dlkm partition

[BoardConfigGsiCommon.mk]

BOARD_USES_SYSTEM_DLKMIMAGE := true
BOARD_SYSTEM_DLKMIMAGE_FILE_SYSTEM_TYPE := ext4
TARGET_COPY_OUT_SYSTEM_DLKM := system_dlkm

[gsi_release.mk]

PRODUCT_BUILD_SYSTEM_DLKM_IMAGE := false

Starting from Android 13, all devices must include a system_dlkm partition. GSI enables system_dlkm to support the devices with system_dlkm partition, and be compatible with old devices without a system_dlkm partition.

With these configurations, /system/system_dlkm would not be created. Instead, a /system/lib/modules -> /system_dlkm/lib/modules symlink is created.

For device without system_dlkm partition, the symlink would be dangling. The dangling symlink shouldn‘t be followed anyway because the device doesn’t use system_dlkm.

For device with system_dlkm, they can load modules via that path normally like when they are using their original system image.

SystemUI overlays

Some devices access the private android framework resource by @*android: while overlaying their SystemUI setting status_bar_header_height_keyguard. However, referencing private framework resource IDs from RRO packages in the vendor partition crashes on these devices when GSI is used. This is because private framework resource don't have a stable ID, and these vendor RRO packages would be referencing to dangling resource references after GSI is used (b/245806899).

In order to prevent SystemUI crash, GSI adds a runtime resource overlay in the system_ext partition, which have higher overlay precedence than RROs on vendor partition, so the problematic vendor RROs would be overridden.

Lifetime of this package:

Starts at: Android 14.
Deprecation plan: TBD, depends on b/254581880.