GTI9300PARAM¶

You can dump the PARAM partition for the Galaxy SIII (GT-I9300) like that:

adb pull /dev/block/platform/dw_mmc/by-name/PARAM PARAM.img

That file at first looks like a tar archive.

$ file PARAM.img
PARAM.img: POSIX tar archive (GNU)

And it indeed does contain a tarball:

$ tar tvf PARAM.img
-rw-r--r-- se.infra/se.infra 3624 2013-11-28 13:33 adv-env.img
-rw-r--r-- se.infra/se.infra 42023 2013-11-28 13:33 ani_upload_1_kernel_panic.jpg
-rw-r--r-- se.infra/se.infra 39255 2013-11-28 13:33 ani_upload_2_cp_crash.jpg
-rw-r--r-- se.infra/se.infra 47443 2013-11-28 13:33 ani_upload_3_forced_upload.jpg
-rw-r--r-- se.infra/se.infra 10810 2013-11-28 13:33 ani_upload_4_hardware_reset.jpg
-rw-r--r-- se.infra/se.infra 11586 2013-11-28 13:33 ani_upload_4_smpl.jpg
-rw-r--r-- se.infra/se.infra 54151 2013-11-28 13:33 ani_upload_4_unknown_reset.jpg
-rw-r--r-- se.infra/se.infra 11495 2013-11-28 13:33 ani_upload_4_watchdog_reset.jpg
-rw-r--r-- se.infra/se.infra 12276 2013-11-28 13:33 ani_upload_4_wtsr.jpg
-rw-r--r-- se.infra/se.infra  9703 2013-11-28 13:33 ani_upload_4_wtsr_smpl.jpg
-rw-r--r-- se.infra/se.infra 12711 2013-11-28 13:33 ani_upload_5_user_fault.jpg
-rw-r--r-- se.infra/se.infra 19098 2013-11-28 13:33 ani_upload_6_hsic_disconnected.jpg
-rw-r--r-- se.infra/se.infra 84123 2013-11-28 13:33 download_error.jpg
-rw-r--r-- se.infra/se.infra 73061 2013-11-28 13:33 download.jpg
-rw-r--r-- se.infra/se.infra 64410 2013-11-28 13:33 logo.jpg
-rw-r--r-- se.infra/se.infra 37205 2013-11-28 13:33 lpm.jpg
-rw-r--r-- se.infra/se.infra 36572 2013-11-28 13:33 lpm_wireless.jpg
-rw-r--r-- se.infra/se.infra 91511 2013-11-28 13:33 secure_error.jpg
-rwxr-xr-x se.infra/se.infra  5851 2013-11-28 13:33 sud_0.jpg
-rwxr-xr-x se.infra/se.infra  2713 2013-11-28 13:33 sud_1.jpg
-rwxr-xr-x se.infra/se.infra  5634 2013-11-28 13:33 sud_2.jpg
-rwxr-xr-x se.infra/se.infra  6292 2013-11-28 13:33 sud_3.jpg
-rwxr-xr-x se.infra/se.infra  4604 2013-11-28 13:33 sud_4.jpg
-rwxr-xr-x se.infra/se.infra  5706 2013-11-28 13:33 sud_5.jpg
-rwxr-xr-x se.infra/se.infra  6792 2013-11-28 13:33 sud_6.jpg
-rwxr-xr-x se.infra/se.infra  3885 2013-11-28 13:33 sud_7.jpg
-rwxr-xr-x se.infra/se.infra  6826 2013-11-28 13:33 sud_8.jpg
-rwxr-xr-x se.infra/se.infra  6528 2013-11-28 13:33 sud_9.jpg
-rw-r--r-- se.infra/se.infra 168616 2013-11-28 13:33 warning.jpg

The size of the PARAM.img file is exactly 8MiB:

$ ls -lah PARAM.img 
[...] 8.0M [...] PARAM.img
$ ls -la PARAM.img 
[...] 8388608 [...] PARAM.img

And we can get the size of the tarball with --totals:

$ man tar
  [...]
  --totals[=SIGNAL]
         Print  total bytes after processing the archive. [...]

For example:

$ tar  --totals -tf PARAM.img
adv-env.img
[many files]
warning.jpg
Total bytes read: 911360 (890KiB, 286MiB/s)

So here the tarball terminates way beyond the end.

911360 is 0xde800:

$ python
[...]
>>> hex(911360)
'0xde800'

But we still have things after the tarball:

$ hexdump -C PARAM.img
000dd4a0  05 00 14 00 50 07 ff d9  00 00 00 00 00 00 00 00  |....P...........|
000dd4b0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00700000  03 00 fe ca 00 01 00 00  00 00 00 00 00 00 00 00  |................|
00700010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00700200  00 00 00 00 03 00 00 00  4c 4f 00 00 00 00 00 00  |........LO......|
00700210  00 00 00 00 03 00 00 00  01 00 00 00 00 00 00 00  |................|
00700220  00 00 00 00 00 00 00 00  63 6f 6e 73 6f 6c 65 3d  |........console=|
00700230  72 61 6d 20 6c 6f 67 6c  65 76 65 6c 3d 34 00 00  |ram loglevel=4..|
00700240  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00700e20  00 00 00 00 00 00 00 00  ff ff ff ff ff ef 7f ff  |................|
00700e30  ff ff f7 ff ff ff f7 ff  ff fe ff ff ff ff 7f ff  |................|
00700e40  fb ef ff ff ff fb ff df  ff ff ff ff ff ff ff ff  |................|
00700e50  df bf ff ff 7f ef f7 ff  f7 ff ff ff ff fe ff ff  |................|
00700e60  ff ff ff ff ef fb ff ef  ff fb ff ff fd ff f7 ef  |................|
00700e70  ff ff ff ff f5 ff ff ff  ff ff ff ff ff ff ff ff  |................|
00700e80  ff ff ff fe ff ef ff ff  ff bf fd ff ff ff ff ff  |................|
00700e90  ff ff ff ff ff ff f7 fb  ff ff ff eb ff ff ff eb  |................|
00700ea0  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff fb  |................|
00700eb0  ff ff ff ff ff ff ff ff  ff ff ff df ff ff ff ff  |................|
00700ec0  ff ff ff ff ff ff f7 ff  ff ff ff ff ff ff ff ff  |................|
00700ed0  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff fb  |................|
00700ee0  df ff ff ff ff ff ff ff  ff ff ff ff ff ff d7 ff  |................|
00700ef0  ff ff ff af ff ff ff fe  ff ff ff ff ff ff ff ff  |................|
00700f00  ff ef ff ff ff 7f ff ff  ff df ff ff f7 ff ff ff  |................|
00700f10  ff ff ff ff ff ff ff ff  ff ff ff ef ff ff f7 ff  |................|
00700f20  ff ff ff ff ff ff ff ff  ff fe ef ff ff ef fb df  |................|
00700f30  ff ff ff ff ff fb ff ff  ff ff ff ff ff ff ff ff  |................|
00700f40  ff ff f5 ff ff ff ff fb  ff ff ff ff ff ff ff ff  |................|
00700f50  fb ff ff fb fd ff ff ff  ff ff ff ff ff ff ff ff  |................|
00700f60  f7 ff ff ef f7 ff ff ef  ff ff ff ff ff 9e ff fd  |................|
00700f70  ff ff ff ff fb ff ff de  f3 fb ff ff ff ef df ff  |................|
00700f80  ff ff ff ff ff fb ff bf  ff ff ff ff ff ff ff fd  |................|
00700f90  ff fe f7 fe ff eb ff ff  ff fb ff ff df ff ff ff  |................|
00700fa0  df ff ff ff ff ff ff ff  ff ff fb ff ff ff ff fb  |................|
00700fb0  ff ff ff df ff ff ff ff  fe fe fe ff ff f7 ff ff  |................|
00700fc0  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff fb  |................|
00700fd0  fd ff ff ff ff fd ff ff  ff ff ff ff fe ff ff ff  |................|
00700fe0  ff ff df ff ff ff ff fb  ff ff ff ff ff ff ff ff  |................|
00700ff0  ff f7 df ff ff ff ff ff  ff ff ff ff ff ff ff ff  |................|
00701000  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
007ffc00  d4 ad 55 ff 52 e9 ed 4c  f8 d1 9c 08 79 b6 e9 6c  |..U.R..L....y..l|
007ffc10  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00800000

Questions:

Can we ignore what is after the tarball and grow it to 8MiB?
Does what's after contains encrypted data for the bootloader?

adv_env.img¶

Here's the content of the adv-env.img file:

$ hexdump -C adv-env.img 
00000000  03 00 fe ca 00 01 00 00  00 00 00 00 00 00 00 00  |................|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000200  04 00 00 00 01 00 00 00  4c 4f 00 00 00 00 00 00  |........LO......|
00000210  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000220  00 00 00 00 00 00 00 00  63 6f 6e 73 6f 6c 65 3d  |........console=|
00000230  72 61 6d 20 6c 6f 67 6c  65 76 65 6c 3d 34 00 00  |ram loglevel=4..|
00000240  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000e20  00 00 00 00 00 00 00 00                           |........|
00000e28

Questions:

Why are the kernel parameters repeated again after the end of the tarball?
Where are the updated kernel parameters stored?
Are the default and in-use kernel parameters stored at different location?

kenrel command line¶

Default kernel command line: console=ram loglevel=4

Test:

change to console=ram loglevel=8 through the bootloader setenv command
run saveenv
reboot and validate that it's really changed with printenv
observe the results on the filesystem

See MidasBootloader for more details on how to change the command line parameters.

After changing the environment variable, we still have loglevel=4 in the adv-env.img file that is in the tarball:
adv-env.img

$ hexdump -C adv-env.img 
00000000  03 00 fe ca 00 01 00 00  00 00 00 00 00 00 00 00  |................|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000200  04 00 00 00 01 00 00 00  4c 4f 00 00 00 00 00 00  |........LO......|
00000210  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000220  00 00 00 00 00 00 00 00  63 6f 6e 73 6f 6c 65 3d  |........console=|
00000230  72 61 6d 20 6c 6f 67 6c  65 76 65 6c 3d 34 00 00  |ram loglevel=4..|
00000240  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000e20  00 00 00 00 00 00 00 00                           |........|
00000e28

So these must be the default parameters.

And the actual kernel parameters were instead saved after the tarball:

$ hexdump PARAM.img
*
00700200  00 00 00 00 03 00 00 00  4c 4f 00 00 00 00 00 00  |........LO......|
00700210  00 00 00 00 03 00 00 00  01 00 00 00 00 00 00 00  |................|
00700220  00 00 00 00 00 00 00 00  63 6f 6e 73 6f 6c 65 3d  |........console=|
00700230  72 61 6d 20 6c 6f 67 6c  65 76 65 6c 3d 38 00 00  |ram loglevel=8..|
00700240  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*

Results:

Since the s-boot 4.0 bootloader on several Exynos 4412 devices (GT-I9300, GT-I9305, GT-N7100, GT-N7105) doesn't take into account the boot.img kenrel parameters, we can then try to change them by editing the PARAM.img after the tarball.
There is valuable info after the tarball => don't make the tarball grow too much.