[Asus  Eee Pad Transformer Prime] craigacgomez:
What is APX mode?

APX mode is basically a programming mode or download mode for nVidia based devices. On a development device or an unrestricted device, when you get into APX mode, you can program your device using nvflash commands. Most production devices lock down APX mode and disable nvflash access. This is where wheelie comes into the picture for our devices. If you cannot access APX mode, you have probably permanently bricked your device.

What is wheelie?

Wheelie is an nvflash pre-loader that boots the tablet into an nvflash ready mode that lets you use regular nvflash commands (with -r prepended!). Wheelie was created by the amazing folks at AndroidRoot. Wheelie uses the "device specific" blob.bin file to bootstrap the device in APX mode and allow nvflash access. The blob.bin file has information like the Chip UID which is different for each devices and cannot be used interchangeably. If you get you device repaired or RMA'd and the motherboard is replaced, you would need to regenerate the blob.bin file.

What is nvflash?

nvflash is a low-level flash utility for nVidia based devices which gives you low level access to the system to flash, format, recover, repartition and do many more functions. It is a very powerful tool and should be used with caution. Read and follow all instruction carefully when using nvflash.

What is "-r" in the nvflash command?

The whole purpose of -r or --resume is to tell nvflash that the device is already running the nv3pserver (nvflash recovery mode), without -r or --resume it will try to do the preflight that wheelie does for us.

What is "--download X" in the nvflash command?

This parameter in the nvflash command is used to download/flash the specified file to partition X in the device. So the command "nvflash -r --download 4 blob.EBT" with download/flash the file blob.EBT to partition 4. These partitions are defined in the device partition table. The flash.cfg file in your nvflash backup is the partition table description if you want to know more details.

What is "--go" in the nvflash command?

This parameter in the nvflash command is used to boot bootloader after nvflash completes instead of looping in nv3pserver in resume mode. Basically it should exit resume mode and reboot your device.

What is BlobTools?

Once again, this is the genius brainchild and result of the amazing folks at AndroidRoot. The Asus Transformer series uses "blobs" to flash stuff. A blob can have multiple partitions (system, boot, recovery, bootloader). Blobs are moved to the staging partition (/dev/block/mmcblk0p4) and are automatically flashed upon reboot. The blob header defines where the different files in a blob get flashed to (boot gets flash to the boot partition, system to the system partition, etc.). BlobTools in a utility to create and extract these staging blobs. All blobs need to be extracted before being using with nvflash.

I have already upgraded to Jelly Bean. Can I still use nvFlash?

At the moment, nvFlash can only be enabled if the device is using the 9.4.2.28 ICS bootloader. If you have not yet enabled nvFlash and you have upgraded to the stock Jelly Bean ROM, you will have the 10.4.2.15 bootloader and you will no longer be able to enable nvFlash.

If you have already enabled nvFlash before upgrading to the stock Jelly Bean ROM, you will continue to have nvFlash access even though your bootloader was upgraded.