Replicant

h1. AddingADB

In this tutorial we'll add adb root support to an existing Replicant release.

This is valid for the following configuration:

* *Image*: replicant-6.0-0004-rc1-maguro.zip

* *Device*: Galaxy Nexus (GT-I9250)

You'll need to adapt it slightly for other devices.

First extract the boot.img from the zip

<pre>

$ mkdir temp

$ cd temp 

$ unzip ../replicant-6.0-0004-rc1-maguro.zip

$ file boot.img

boot.img: Android bootimg, kernel, ramdisk, page size: 2048, cmdline (androidboot.hardware=tuna)

</pre>

Then extract the kernel, and initramfs from the boot.img. Also save the infos such as the load address, etc in boot.txt:

<pre>

$ unbootimg --kernel kernel.img --ramdisk ramdisk.cpio.gz -i boot.img | tee boot.txt

total image size:   5619712

kernel size:        4604340

kernel load addr:   0x80008000

ramdisk size:       1009915

ramdisk load addr:  0x81000000

2nd boot size:      0

2nd boot load addr: 0x80f00000

kernel tags addr:   0x80000100

page size:          2048

board:              `'

cmdline:            `androidboot.hardware=tuna'

id:                 9b90141066f527ecd3909d2ab8e383ebd995fd40000

</pre>

Then uncompress the initramfs

<pre>

$ gunzip ramdisk.cpio.gz

$ file ramdisk.cpio 

ramdisk.cpio: ASCII cpio archive (SVR4 with no CRC)

</pre>

Then edit the default.props, we use sed on the raw cpio image for simplicity (we don't have permissions and username to take care of this way):

<pre>

$ sed 's#ro.adb.secure=1#               #' -i ramdisk.cpio

$ sed 's#ro.secure=1#ro.secure=0#' -i ramdisk.cpio

$ sed 's#persist.sys.usb.config=none#persist.sys.usb.config=adb #' -i ramdisk.cpio

</pre>

Then recompress the initramfs

<pre>

$ gzip ramdisk.cpio

</pre>

We then recreate the image with the infos we saved in boot.txt. Note that the base is 0x80000000. The kernel has an offset and will be in 0x80008000:

<pre>

$ mkbootimg --cmdline="androidboot.hardware=tuna" --kernel kernel.img --ramdisk ramdisk.cpio.gz  --base 0x80000000 -o boot_new.img

</pre>

Verify that we got all the arguments right:

<pre>

$ unbootimg -i boot_new.img | tee boot_new.txt

$ diff -u boot.txt boot_new.txt

$ --- boot.txt	2020-02-18 00:39:59.890285634 +0100

+++ boot_new.txt	2020-02-18 00:44:16.208897037 +0100

@@ -1,7 +1,7 @@

 total image size:   5619712

 kernel size:        4604340

 kernel load addr:   0x80008000

-ramdisk size:       1009915

+ramdisk size:       1010280

 ramdisk load addr:  0x81000000

 2nd boot size:      0

 2nd boot load addr: 0x80f00000

@@ -9,4 +9,4 @@

 page size:          2048

 board:              `'

 cmdline:            `androidboot.hardware=tuna'

-id:                 9b90141066f527ecd3909d2ab8e383ebd995fd40000

+id:                 dd37b2ae1e50be62fe5c94b81b85aa56ffea17be000

</pre>

Reflash the image:

<pre>

heimdall flash --boot boot.img --recovery boot.img

</pre>

Then you can use adb:

<pre>

$ adb logcat -b main

</pre>