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+# GSI
+
+This document introduces special GSI settings for facilitating xTS-on-GSI with
+a single image.
+
+## Changes in runtime resource overlays (RRO)
+
+### 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.