27 Feb 2014 jas   » (Master)

Replicant 4.2 on Samsung S3

Since November 2013 I have been using Replicant on my Samsung S3 as an alternative OS. The experience has been good for everyday use. The limits (due to non-free software components) compared to a “normal” S3 (running vendor ROM or CyanogenMod) is lack of GPS/wifi/bluetooth/NFC/frontcamera functionality — although it is easy to get some of that working again, including GPS, which is nice for my geocaching hobby. The Replicant software is stable for being an Android platform; better than my Nexus 7 (2nd generation) tablet which I got around the same time that runs an unmodified version of Android. The S3 has crashed around ten times in these four months. I’ve lost track of the number of N7 crashes, especially after the upgrade to Android 4.4. I use the N7 significantly less than the S3, reinforcing my impression that Replicant is a stable Android. I have not had any other problem that I couldn’t explain, and have rarely had to reboot the device.

The Replicant project recently released version 4.2 and while I don’t expect the release to resolve any problem for me, I decided it was time to upgrade and learn something new. This time I decided to use the pre-built ROM images rather to build my own because I had issues building replicant 4.2 on my Debian wheezy machine (C++ compilation errors which apparently does not happen if you use a newer compiler).

Before the installation, I wanted to have a full backup of the phone to avoid losing data. I use SMS Backup+ to keep a backup of my call log, SMS and MMS on my own IMAP server. I use oandbackup to take a backup of all software and settings on the phone. I use DAVDroid for my contacts and calendar (using a Radicale server), and reluctantly still use aCal in order to access my Google Calendar (because Google does not implement RFC 5397 properly so it doesn’t work with DAVDroid). Alas all that software is not sufficient for backup purposes, for example photos are still not copied elsewhere. In order to have a complete backup of the phone, I connect the phone using a USB cable and enable USB tethering on the phone. The network is automatically set up on my Debian machine, I did not have to do anything. Then I invoke the following commands to take a backup using rsync:

adb shell dropbear -F -E &
sudo rsync -av --delete --exclude /dev --exclude /acct --exclude /sys --exclude /proc -e ssh root@192.168.42.129:/ /root/s3-bup/

Now feeling safe that I would not lose any data, I removed the SIM card from my phone (to avoid having calls, SMS or cell data interrupt during the installation) and followed the Replicant Samsung S3 installation documentation. Installation was straightforward. I booted up the newly installed ROM and familiarized myself with it. My first reaction was that the graphics felt a bit slower compared to Replicant 4.0, but it is hard to tell for certain.

I connected to the network using USB tethering and took a quick rsync-backup of the freshly installed phone, to have a starting point for future backups. Since my IMAP and CardDav/CalDav servers use certificates signed by CACert I first had to install the CACert trust anchors, to get SMS Backup+ and DAVDroid to connect. For some reason it was not sufficient to add only the root CACert certificate, so I had to add the Class 3 sub-ca cert as well. To load the certs, I invoke the following commands, selecting ‘Install from SD Card’ when the menu is invoked (twice).

adb push root.crt /sdcard/
adb shell am start -n "com.android.settings/.Settings\"\$\"SecuritySettingsActivity"
adb push class3.crt /sdcard/
adb shell am start -n "com.android.settings/.Settings\"\$\"SecuritySettingsActivity"

I restore apps with oandbackup, and I select a set of important apps that I want restored with settings preserved, including aCal, K9, Xabber, c:geo, OsmAnd~, NewsBlur, Google Authenticator. I install SMS Backup+ from FDroid separately and configure it, SMS Backup+ doesn’t seem to want to restore anything if the app was restored with settings using oandbackup. I install and configure the DAVdroid account with the server URL, and watch it populate my address book and calendar with information.

After organizing the icons on the launcher screen, and changing the wallpaper, I’m up and running with Replicant 4.2. This upgrade effort took me around two days to complete, with around half of the time consumed by exploring different ways to do the rsync backup before I settled on dropbear and USB tethering. Compared to the last time, when I spent almost two weeks researching various options and preparing for the install, this felt like a swift process.

I spent some time researching how to get the various non-free components running. This is of course sub-optimal, and the Replicant project does not endorse non-free software. Alas there aren’t any devices out there that meets my requirements and use only free software. Personally, I feel using a free core OS like Replicant and then adding some non-free components back is a better approach than using CyanogenMod directly, or (horror) the stock ROM. Even better is of course to not add these components back, but you have to decide for yourselves which trade-offs you want to make. The Replicant wiki has a somewhat outdated page on Samsung S3 firmware. Below are my notes for each component, which applies to Replicant 4.2 0001. You need to first prepare your device a bit using these commands, and it is a good idea to reboot the device after installing the files.

adb root
adb shell mount -o rw,remount /system
adb shell mkdir /system/vendor/firmware
adb shell chmod 755 /system/vendor/firmware

GPS: The required files are the same as for Replicant 4.0, and using the files from CyanogenMod 10.1.3 works fine. The following commands load them onto the device. Note that this will load code that will execute on your main CPU which is particularly bothersome. There seems to exist a number of different versions of these files, CyanogenMod have the same gpsd and gps.exynos4.so in version 10.1.3 and 10.2 but the libsecril-client.so differs between 10.1.3 and 10.2. All files differ from the files I got with my stock Samsung ROM on this device (MD5 checksums in my previous blog). I have not investigated how these versions differs or which of them should be recommended. I use the files from CyanogenMod 10.1.3 because it matches the Android version and because the files are easily available.

adb push cm-10.1.3-i9300/system/bin/gpsd /system/bin/gpsd
adb shell chmod 755 /system/bin/gpsd
adb push cm-10.1.3-i9300/system/lib/hw/gps.exynos4.so /system/lib/hw/gps.exynos4.so
adb push cm-10.1.3-i9300/system/lib/libsecril-client.so /system/lib/libsecril-client.so
adb shell chmod 644 /system/lib/hw/gps.exynos4.so /system/lib/libsecril-client.so

Bluetooth: Only one file has to be installed, apparently firmware loaded onto the Bluetooth chip. Cyanogenmod 10.1.3 and 10.2 contains identical files, which has a string in it “BCM4334B0 37.4MHz Class1.5 Samsung D2″. The file I got with my stock ROM has a string in it “BCM4334B0 37.4MHz Class1.5 Samsung M0″. I don’t know the difference, although I have seen that D2 sometimes refers to the US version of a Samsung device. My device is the international version, but it seems to work anyway.

adb push cm-10.1.3-i9300/system/bin/bcm4334.hcd /system/vendor/firmware/bcm4334.hcd
adb shell chmod 644 /system/vendor/firmware/bcm4334.hcd

Front Camera: Two files has to be installed, apparently firmware loaded onto the Camera chip. CyanogenMod 10.1.3 and 10.2 contains identical files, which has a string in it “[E4412 520-2012/08/30 17:35:56]OABH30″. The file I got with my stock ROM has a string in it “[E4412 533-2012/10/06 14:38:46]OABJ06″. I don’t know the difference.

adb push cm-10.1.3-i9300/system/vendor/firmware/fimc_is_fw.bin /system/vendor/firmware/fimc_is_fw.bin
adb push cm-10.1.3-i9300/system/vendor/firmware/setfile.bin /system/vendor/firmware/setfile.bin
adb shell chmod 644 /system/vendor/firmware/fimc_is_fw.bin /system/vendor/firmware/setfile.bin

NFC: I’m happy that I got NFC to work, this was one of my main issues with Replicant 4.0 (see my earlier blog post). Only one file is needed, however CyanogenMod does not seem to distribute it so you have to get it from your stock ROM or elsewhere. The md5 of the file I have is b9364ba59de1947d4588f588229bae20 (and no I will not send it to you). I have tested it with the YubiKey NEO and the Yubico Authenticator app.

adb push clockworkmod/blobs/ee6/7188ca465cf01dd355a92685a42361e113f886ef44e96d371fdaebf57acae /system/vendor/firmware/libpn544_fw.so
adb shell chmod 644 /system/vendor/firmware/libpn544_fw.so

Wifi: I haven’t gotten wifi to work, although I have not tried very hard. Loading the CyanogenMod firmwares makes my device find wireless networks, but when I try to authenticate (WPA-PSK2), I get failures. Possibly some other files has to be loaded as well.

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Syndicated 2014-02-27 11:07:45 from Simon Josefsson's blog

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