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Feature #1873

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Remove UMS partition

Added by Matthias-Christian Ott about 6 years ago. Updated about 3 years ago.

Status:
New
Priority:
Normal
Assignee:
-
Category:
-
Target version:
Start date:
02/12/2018
Due date:
% Done:

80%

Estimated time:
1.00 h
Resolution:
Device:
Galaxy S 2 (I9100)
Grant:
Type of work:
Any programming languages (scripts, C, etc)

Description

The stock ROM of Samsung Galaxy S II (i9100) does include an UMS (USB Mass Storage) partition. The device was first delivered with Android 2.3 when emulated storage (/data/media) did not exist. So it had an internal partition that behaved like a non-removable portable storage and similar to a SD card.

Android 3.0 introduced emulated storage that has many advantages, for example a proper file system, encryption and multi-user support. So starting with Android 3.0 the UMS partition is not needed anymore and the DATAFS partition can be used as emulated storage.

Grim Kriegor provided a patch and PIT file that shrink the UMS partition to a minimum, remove its fstab entry and set ro.vold.primary_physical to 0 and thus enable emulated storage.

If Replicant requires the device to repartitioned and removes the UMS partition, it will break compatibility with the stock ROM, requires the user to backup their data and complicates the installation. However, the partition layout that came with the stock ROM of the device that I have requires the partition layout to be changed anyhow because FACTORYFS partition is too small. So I think it makes sense to provide a PIT file to repartition the device.

So I think the following changes are required:

  • provide a PIT to enlarge the FACTORYFS and DATAFS partitions and shrink or disable the UMS partition
  • update the installation instructions to include a download link to the PIT file and an additional command line switch to heimdall
  • change the fstab to remove the UMS partition
  • set ro.vold.primary_physical to 0
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