From b90201854bd521e92a2134dc7fbafa9cf129b914 Mon Sep 17 00:00:00 2001 From: Jonas Smedegaard Date: Sat, 23 Jun 2018 19:26:28 +0200 Subject: Initial draft. --- TECH.md | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 75 insertions(+) create mode 100644 TECH.md (limited to 'TECH.md') diff --git a/TECH.md b/TECH.md new file mode 100644 index 0000000..d3f36bf --- /dev/null +++ b/TECH.md @@ -0,0 +1,75 @@ +# 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" -- cgit v1.2.3