How I obtained Stock ROMs

The first and most important step to obtaining the stock system ROM is to figure out your partitioning scheme so that you know what you need to and should not backup. To figure this out, you will need to view your Partition Information Table (PIT) - a GPT based descriptor for your NAND flash's logical layout. For the most authoritative source of information that I have found regarding the partitioning on Android phones, check out El Grande Partition thread over at xda-developers.com To get a good sense of your partitioning, you will need both the block device names (used by the mount command) and the actual partition names. This translates roughly into: You need the output of /proc/partitions and parted. Once you have root, getting /proc/partitions is easy. Simply type "cat /proc/partitions":

app_128@android:/ $ su root@android:/ # cat /proc/partitions

This results in the following output:

major	minor	#blocks	name
179	0	7634944	mmcblk0
179	1	61440	mmcblk0p1
179	2	128	mmcblk0p2
179	3	256	mmcblk0p3
179	4	512	mmcblk0p4
179	5	2048	mmcblk0p5
179	6	512	mmcblk0p6
179	7	10240	mmcblk0p7
179	8	512	mmcblk0p8
179	9	512	mmcblk0p9
179	10	10240	mmcblk0p10
179	11	13952	mmcblk0p11
179	12	3072	mmcblk0p12
179	13	3072	mmcblk0p13
179	14	1536000	mmcblk0p14
179	15	5079040	mmcblk0p15
179	16	8192	mmcblk0p16
179	17	860160	mmcblk0p17
179	18	10240	mmcblk0p18
179	19	10240	mmcblk0p19
179	20	6144	mmcblk0p20
179	21	3072	mmcblk0p21
179	22	8	mmcblk0p22
179	23	5120	mmcblk0p23
179	64	2048	mmcblk0boot1
179	32	2048	mmcblk0boot0

To get the output from parted requires a little more skill as parted is not present on most phones by default and it is not included with busybox. Thanks to the guys over at droidforum however, you can download this from here. Once you have unzipped this file and uploaded it to your device, either by placing it into disk mode, using adb push or by taking out the mini-SD card and putting it into your computer, you can then use parted to dump the partition table:

app_128@android:/ $ su root@android:/ #cp /mnt/extSdCard/parted

Number	Start	End	Size	File system	Name	Flags
1	4194kB	67.1MB	62.9MB		modem
2	67.1MB	67.2MB	131kB		sbl1
3	67.2MB	67.5MB	262kB		sbl2
4	67.5MB	68.0MB	524kB		sbl3
5	68.0MB	70.1MB	2097kB		aboot
6	70.1MB	70.6MB	524kB		rpm
7	70.6MB	81.1MB	10.5MB		boot
8	81.1MB	81.7MB	524kB		tz
9	81.7MB	82.2MB	524kB		pad
10	82.2MB	92.7MB	10.5MB		param
11	92.7MB	107MB	14.3MB	ext4	efs
12	107MB	110MB	3146kB		modemst1
13	110MB	113MB	3146kB		modemst2
14	113MB	1686MB	1573MB	ext4	system
15	1686MB	6887MB	5201MB	ext4	userdata
16	6887MB	6895MB	8389kB	ext4	persist
17	6895MB	7776MB	881MB	ext4	cache
18	7776MB	7787MB	10.5MB		recovery
19	7787MB	7797MB	10.5MB		fota
20	7797MB	7804MB	6291kB		backup
21	7804MB	7807MB	3146kB		fsg
22	7807MB	7807MB	8192B		ssd
23	7807MB	7812MB	5243kB		grow

dd if=/dev/block/mmcblk0p1 of=/sdcard/modem.bin
dd if=/dev/block/mmcblk0p2 of=/sdcard/sbl1.mbn
dd if=/dev/block/mmcblk0p3 of=/sdcard/sbl2.mbn
dd if=/dev/block/mmcblk0p4 of=/sdcard/sbl3.mbn
dd if=/dev/block/mmcblk0p5 of=/sdcard/aboot.mbn
dd if=/dev/block/mmcblk0p6 of=/sdcard/rpm.mbn
dd if=/dev/block/mmcblk0p7 of=/sdcard/boot.img
dd if=/dev/block/mmcblk0p8 of=/sdcard/tz.mbn
dd if=/dev/block/mmcblk0p9 of=/sdcard/pad.mbn
dd if=/dev/block/mmcblk0p10 of=/sdcard/param.mbn
dd if=/dev/block/mmcblk0p12 of=/sdcard/modemst1.bin
dd if=/dev/block/mmcblk0p13 of=/sdcard/modemst2.bin
dd if=/dev/block/mmcblk0p16 of=/sdcard/persist.ext4
dd if=/dev/block/mmcblk0p18 of=/sdcard/recovery.img
dd if=/dev/block/mmcblk0p21 of=/sdcard/fsg.mbn
dd if=/dev/block/mmcblk0p23 of=/sdcard/grow.mbn