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+# Android administration
+
+## Baseband radio
+
+Baseband code is in official releases from Samsung,
+but separatefrom 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
+
+[REPIT]; https://github.com/Lanchon/REPIT
+  "tool to automatic repartition select devices while preserving data"