U-boot with fastboot support for k3

[giorgio130]

Hi everyone! I'm trying to port the u-boot found in newer kindles, with fastboot support, to the kindle 3. Next step will be to remove the image size limitation to flash also the system partition.
I've got a first release that compiles fine, but I'm unsure of how to test this.
Source and a binary are attached to this thread, so directions and/or testers are welcome

[eureka]

Originally Posted by giorgio130

Hi everyone! I'm trying to port the u-boot found in newer kindles, with fastboot support, to the kindle 3. Next step will be to remove the image size limitation to flash also the system partition.

Size of flashed image in fastboot mode on newer Kindles is limited by RAM size only (minus some MB for U-Boot itself and system buffers). But, for example, KT has 256MB RAM and KT's rootfs on system partition (/dev/mmcblk0p1) is about 340MB: that's why rootfs image can be flashed in fastboot mode only partially. It's understandable limitation inherited from standard fastboot.

So, to clarify things, you can't just "remove" size limitation. You'll need to implement new fastboot command for "chunked" downloading and flashing of "big" images. And change fastboot tool to support this new command.

[geekmaster]

And while adding features to fastboot protocol, how about adding remote debugging and an mmc hex editor?

[giorgio130]

Originally Posted by eureka

Size of flashed image in fastboot mode on newer Kindles is limited by RAM size only (minus some MB for U-Boot itself and system buffers). But, for example, KT has 256MB RAM and KT's rootfs on system partition (/dev/mmcblk0p1) is about 340MB: that's why rootfs image can be flashed in fastboot mode only partially. It's understandable limitation inherited from standard fastboot.

So, to clarify things, you can't just "remove" size limitation. You'll need to implement new fastboot command for "chunked" downloading and flashing of "big" images. And change fastboot tool to support this new command.

Thanks for the explanation, I couldn't find the cause anywhere. But I actually think that android phones don't have this kind of limitation... Or maybe they just keep their partition size under the amount of available ram?
I'll do some research. BTW, do you know if the limit of 72 kb for the first-stage u-boot applies even to the kindle 3? I didn't find any reference to a "bist" u-boot on this platform, so I'd assume no...

[eureka]

Originally Posted by giorgio130

Thanks for the explanation, I couldn't find the cause anywhere.

It's at include/configs/imx50_yoshi_bist.h:

#define CONFIG_FASTBOOT_MAX_DOWNLOAD_LEN  ((get_dram_size()) - (2*1024*1024) - (CONFIG_FASTBOOT_TEMP_BUFFER - CONFIG_SYS_SDRAM_BASE))

Originally Posted by giorgio130

But I actually think that android phones don't have this kind of limitation... Or maybe they just keep their partition size under the amount of available ram?

Exactly.

Originally Posted by giorgio130

I'll do some research. BTW, do you know if the limit of 72 kb for the first-stage u-boot applies even to the kindle 3? I didn't find any reference to a "bist" u-boot on this platform, so I'd assume no...

I can't answer, I don't know. 72kb limit was found by reading of Reference Manual for Kindle Touch SoC. I think you should read similar manual for K3 SoC.