What is the format of the "BMP" partition?

/dev/mmcblk0p12 has the name “BMP” and seems to contain swaths of RGB data.

Given that the tool at https://github.com/jwatte/jw_boot_logo doesn’t work anymore, I imagine that the boot logo now lives in that partition?

Is there a document for the format of the data in that partition, or would I have to go reverse engineering again to update the boot image tool?

hello snarky,

we actually not yet support users to generate a customize bmp.blob files to replace the image during system boot-up.

I understand that you don’t. That’s why I want to know if there is any information about the format of the BMP partition, so that I don’t have to debug-dump-reverse-engineer it myself.

The bmp.blob in /bootloader is what gets written to the BMP partition. That hasn’t changed. It’s the bmp.blob itself that’s different - we had to go to a compressed format for Jetson Nano, due to the constraints of the QSPI chip used on that platform (4MB). So every Jetson build got that new compressed format for the bmp.blob.

It’s the same 3 BMPs (NVIDIA green-on-black logo, in 480, 720 and 1080), with the same header that describes those files. The header is generated by the blob creation script. I’m trying to get that released publicly.

For the compressed blob, the header is essentially the same, and it’s followed by the 3 BMP files compressed by lz4c.

HTH,

Tom

lz4c sounds like it gives me something to go on, thanks!

Or if you can release your own tools, that’s good, too :-)

If you are still interested. Looks like I did it. https://devtalk.nvidia.com/default/topic/1065184/jetson-nano/hello-how-can-i-change-the-nvidia-boot-logo-to-my-own-/

Nice! The Open Source model for the win :-)

@TWarren did you ever release the script? If so from which JetPack version?

I believe the BMP tools were released in the latest BSP, 32.4.2 IIRC. @WayneWWW can say w/more certainty.

Hi lfdm,

Please refer to Jetpack4.4 DP, check this readme file and try this tool.

-> Linux_for_Tegra/tools/bmp-splash/bmp-blob-README.txt