Vladimir 'φ-coder/phcoder' Serbinenko wrote: > I feel like we should have a way to update options safely.
Thanks for starting the thread. I hope we'll hear comments on this from all parts of the community. It's a fairly important topic, since it impacts every single board. Even if individual boards using coreboot in production typically do not have new NVRAM settings added, there may be tree-wide options added, and it's important that everything in the field continues to work if a newer version of coreboot is deployed. There is also previous work on the topic: http://www.coreboot.org/Infrastructure_Projects#CMOS_handling in particular: http://www.coreboot.org/Infrastructure_Projects#Provide_update_paths_and_avoid_conflicts_in_addressing (which mentions another solution to the problem) > 2) Have some version field to check and if it mismatches reset CMOS > to default. To avoid having to maintain version manually I propose to > checksum option table and write 16-bit result to CMOS. This does seem like a reasonable approach, but... > 2a) instead of having separate field we could make XOR layout checksum > into CMOS checksum. This would save 2 bytes but will break any existing > users if they check checksum. (IIRC we already have problems with the Linux nvram driver which does checksumming somehow differently. Or maybe that was fixed already.) Vladimir 'φ-coder/phcoder' Serbinenko wrote: > > And why would you need to reset CMOS if trackpad is disabled? > > > > # nvramtool -a > > # nvramtool -w trackpad_enable=Enable > > You could do it in this particular case but user isn't required to know > this. And settings may be something more drammatic. It may happen that > the system doesn't boot with garbage settings at all. The fact that you > have to handle garbage in saved option indicates that something is wrong. ...but the above reminded me that it is ultimately a responsibility of our source code and our design to never let booting fail simply due to some garbage in NVRAM. Code and design really must ensure a working state. Until there exists an update path it's obviously not future proof to add new options to any mainboard. //Peter -- coreboot mailing list: [email protected] http://www.coreboot.org/mailman/listinfo/coreboot
