The Galaxy S23 might be Samsung’s first Android device to use EROFS

The Galaxy S23 might be Samsung’s first Android device to use EROFS for its read-only partitions! The Galaxy Z Fold 4 and previous Samsung flagships use F2FS for their read-only partitions.

  • Left: DiskInfo on Z Fold 4
  • Right: DiskInfo on S23

(Screenshot credits: Chris Wedel)

We don’t have an S23 or Z Fold 4 for comparison, but if you do, you can check out the partitions yourself using the DiskInfo app or by using the Linux ‘mount’ command. EROFS is a performant and space efficient file system for read-only partitions developed by Huawei that has gained popularity among other Android OEMs like Xiaomi and OPPO. It has been supported in Linux since 5.4.

In fact, Google once planned to make it mandatory for Android 13 launch devices to use EROFS for their read-only partitions. However, they relaxed this requirement and now only require kernel support to pass VTS/VSR-13. Google was going to use EROFS for its own Pixel 7 series as well, but they reverted this decision quite late in the development cycle when they discovered a regression in app launch times for some apps like Google Photos.

Thanks to HN user chenxiaolong for first bringing this change to my attention. They examined the firmware of the European S23 Ultra and found that all dynamic partitions under ‘super’ (system, system_ext, product, vendor, odm) were formatted in EROFS.

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