diff options
| -rw-r--r-- | fs_mgr/README.overlayfs.md | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/fs_mgr/README.overlayfs.md b/fs_mgr/README.overlayfs.md index 8784c94b9..2aac2601a 100644 --- a/fs_mgr/README.overlayfs.md +++ b/fs_mgr/README.overlayfs.md @@ -74,7 +74,7 @@ a probe of the filesystem types and space remaining. When *overlayfs* logic is feasible, it will use either the **/cache/overlay/** directory for non-A/B devices, or the **/mnt/scratch/overlay** directory for A/B devices that have -access to *Logical Resizeable Android Partitions*. +access to *Logical Resizable Android Partitions*. The backing store is used as soon as possible in the boot process and can occur at first stage init, or at the mount_all init rc commands. @@ -94,12 +94,17 @@ Caveats and thus free dynamic partition space. - Kernel must have CONFIG_OVERLAY_FS=y and will need to be patched with "*overlayfs: override_creds=off option bypass creator_cred*" - if higher than 4.6. + if kernel is higher than 4.6. + The patch is available on the upstream mailing list and the latest as of + Feb 8 2019 is https://lore.kernel.org/patchwork/patch/1009299/. + This patch adds an override_creds _mount_ option to overlayfs that + permits legacy behavior for systems that do not have overlapping + sepolicy rules, principals of least privilege, which is how Android behaves. - *adb enable-verity* will free up overlayfs and as a bonus the device will be reverted pristine to before any content was updated. Update engine does not take advantage of this, will perform a full OTA. - Update engine may not run if *fs_mgr_overlayfs_is_setup*() reports - true as adb remount overrides are incompatable with an OTA resources. + true as adb remount overrides are incompatible with an OTA resources. - For implementation simplicity on retrofit dynamic partition devices, take the whole alternate super (eg: if "*a*" slot, then the whole of "*system_b*"). |