# Android administration

## Baseband radio

Baseband code is in official releases from Samsung,
but separate from Android source (AOSP)
and (probably therefore) not in CyanogenMod (CM) nor Replicant.

### Updating Baseband radio

Requires. Debian package "heimdall-flash" and binary blob "modem.bin".

Samsung releases are issued only via their Windows-based Kies tool.
Unofficial redistribution are at...:

  * http://www.gsm-file.com/ (need login)
  * http://samsung-updates.com/ (rate-limited)
  * https://samsung-firmware.org/ (rate-limited, need login)
  * https://www.sammobile.com/ (rate-limited, need login)

 1) Fully charge the phone.
 2) Disconnect any cables and turn off the phone.
 3) Hold VOL-DOWN+KEY, press POWER for 2 seconds, then release them all.
 3) Press VOL-UP when asked.
 4) Connect USB-to-PC data cable.
 5) Run "heimdall flash --RADIO modem.bin"

### Version numbers

Version numbers for Samsung releases are strings like "I9300XXUGPB1"
where last 2 characters (the "PB" here)
indicate year and month as roman numbers.

Samsung releases has 3 version numbers.
Commonly only PDA is listed, sometimes also CSC.
Baseband version is different from those,
often listed last (if at all).

Always use baseband version GM2 or newer,
due to its use of [EFSv2][].

CyanogenMod 13 (based on Android 6.0.1)
is [rumored][] to need recent baseband for GPS to work.

Concrete experience:
Two phones bought second-hand in Denmark (but originating elsewhere)
has working GPS with CM13 and these baseband versions:
  * I9300XXUGOK1 e.g. from I9300XXUGOK1_VNZ_NEW_ZEALAND_4.3.zip
    sha1 of modem.bin: 2d4625021ad5931377865eddba7cf1fb18a111da
  * I9300BOUGNB1 e.g. from TNL-I9300XXUGOL2-20160120152855.zip)
    sha1 of modem.bin: c893aaa146d2120fd316cb7d1af4111e1069e990

[EFSv2]: http://forum.xda-developers.com/galaxy-s3/general/ref-imei-efs-stuff-i9300-including-t2393289
  "forum post covering EFS formats and relationship to baseband versions"

[rumored]: https://forum.cyanogenmod.org/topic/123415-gt-i9300-gps-issue-fixed/
  "forum post listing failing and succeeding baseband versions for CM13"


## Recovery

Recovery is a separate minimal rescue system.

Some Recovery systems follow the [IsoRec] structure,
allowing Recovery and regular systems from different vendors
to work together.

[IsoRec]: http://forum.xda-developers.com/galaxy-s2/orig-development/isorec-isolated-recovery-galaxy-s2-t3291176
  "forum post covering Isolated Recovery"


## Partition

Internal storage of some Samsung phones can be repartitioned
using [REPIT].

[REPIT]: https://github.com/Lanchon/REPIT
  "tool to automatic repartition select devices while preserving data"