[G Tablet Q&A, Help & Troubleshooting] rajeevvp:
Unless your part11 (system) has bad blocks on it--in which case nvflash will fail to read it, but, CWM will skip those bad blocks--I see no reason (apart from saving space because CWM's system.img is likely to be the smaller) to replace the nvflash part11.img with CWM's system.img.

On most gTablets, partition 7 is the bootbmp partition--where the 1st splash screen is stored. You can very safely blow this away. On a few other gTablets, including mine, partition 7 is the misc partition (and part 6 is bootbmp) and this too, generally, goes unused, and so can safely be erased.

If you have problems reading back part 6 or part 7, use the "--format_partition" flag to nvflash to clear the partition and then see if the backup fails.

$ [B]sudo ./nvflash --bl bootloader.bin --format_partition 7 --go[/B]

I see that you guys are using CWM's system.img and then editing the gtablet.cfg file to change the size to match. I would strongly discourage doing this. The reason being that the gtablet.cfg is also used as a guide to create partitions. The partitions all have to have certain fixed sizes--the system partition needs to be at least 2048 * 102400 = 200MB to stay in line with ViewSonic's partitioning scheme. If you get a smaller sized file--which is what you'll get with CWM's system.img--and put this in gtablet.cfg and then use "--create" you will end up with a smaller system partition than you or VS intended. In short, leave the gtablet.cfg as is.

Only 4 files are required to do a complete backup and restore if all your partitions can be read without errors by nvflash:

1. The nvflash program.

Any nvflash program from nVIDIA should work. I just tried out one from the latest Linux4Tegra tar file and it worked just fine.

2. A bootloader.bin for the gTablet

This is version of bootloader.bin used (1.1 or 1.2) doesn't matter in most cases as it is not stored on any of the user visible partitions (2 - 12) on the gTablet when used with "nvflash --bl ...". Just make sure, though, that the file is meant for the gTablet. The best place to get them is from VS's official update zip files.

I was able to use a 1.2 bootloader with my 1.1-based ROM and didn't have any problems taking a backup using nvflash or booting into my ROM (GtabComb-b3.3-bl1.1) afterwards. However, if you use the --go flag to "continue normal execution of the downloaded bootloader"--where, normal execution means try booting the standard kernel after the command is done--then your bootloader.bin and the kernel should match.

3. A backup script.

p00r's will do nicely. Here's mine for linux:

#!/bin/sh

sudo ./nvflash --bl bootloader.bin --getbct --bct gtablet.bct --go
sudo ./nvflash -r --getpartitiontable gtablet.cfg
for n in `seq 2 10`
do sudo ./nvflash -r --read $n part$n.img ||
{ echo 1>&2 "$0: nvflash read failed!"; exit 1; }
done
sudo ./nvflash -r --read 11 system.img

4. A restore script.

bekit's is "standard". Here's mine for linux:

#!/bin/sh

sudo ./nvflash --bct gtablet.bct --setbct --bl bootloader.bin --configfile gtablet.cfg --create

The format of the gtablet.cfg file does not matter as long as you use the same nvflash program for both backups and restores and the gtablet.cfg file was created by the same nvflash program.