On 5/4/23 13:39, Michal Simek wrote:
On 5/1/23 16:26, Heinrich Schuchardt wrote:
Linux distributions are interested in providing a single image which enables a high number of boards to boot. This is simple if the boot firmware (EDK II or U-Boot) is installed on flash.
For boards that expect to load a boot loader like U-Boot from an SD-card it is necessary that the firmware locations for different boards on the SD-card don't collide.
When loading from SD-card or eMMC the sector at which the binary starts has to be identified. The following has been implemented:
- start from hard coded sector number
- load file from FAT file system
- load from given partition number
- load from partition with boot flag set (MBR partioning only)
- load from partition with specific type GUID
Loading by partition type GUID seems the most appropriate to avoid collisions between the firmware for different boards.
Often firmware is separated into multiple parts due to firmware restrictions, e.g. U-Boot SPL and main U-Boot (e.g. as .itb file).
Here the same considerations apply. Using a partition type GUID to identify further firmware parts to be loaded is best suited to avoid collisions.
I would suggest to add a recommendation to the EBBR specification to use SoC specific partition type GUIDs to identify firmware to be loaded from SD-card.
Please, provide your feedback.
Isn't this very similar to effort which Andre presented at Fosdem 2019?
https://archive.fosdem.org/2019/schedule/event/one_image_to_rule_them_all/at...
Thanks, Michal
Thanks Michal for the pointer. We are talking about the same topic. The question that was not resolved up to now is how we can avoid conflicts between the U-Boot binaries of different SoCs stored on the same medium. This is where I propose to use GUID partition types.
Best regards
Heinrich