On Thu, May 5, 2016 at 5:53 PM, Mark Brown broonie@kernel.org wrote:
On Thu, May 05, 2016 at 04:21:59PM +0100, Grant Likely wrote:
I think we have everything we need to work around the location of the FW boot image without breaking the UEFI spec. The biggest problem is making sure partitioning tools don't go stomping over required firmware data and rendering systems unbootable. I *think* we can solve that problem by extending the MBR definition to block out a required region and then work around that. Tools can generically see the special region in the MBR and work around it accordingly.
So, let me try to itemize the use cases:
I think there's one other slightly different angle on this which we should address at the same time, creating fresh boot media for a device ("I just unpacked my board and want to write a system image to a SD card"). If we can come up with a standard way of describing the requirements of boards then we could provide a shared database of this information that tools could use. This might also be useful for the less helpful requirements where it's hard to figure out what's going on from the media itself.
Are you talking about for boards that don't have on-board media? For the boards with eMMC, I think the normal use-cases should always be to boot from eMMC (regardless of where the OS is installed). Booting from an SD shouldn't require anything special. The only time to boot firmware from SD is when upgrading the platform firmware, or doing firmware development.
For systems without on-board storage, yes I agree it would be good to have a standard way of describing the layout because the images will always need to be tailored for the board.
g.