On 28/06/2022 09:49, Ard Biesheuvel wrote: > On Thu, 2 Jun 2022 at 19:40, Guilherme G. Piccoli <gpiccoli@xxxxxxxxxx> wrote: >> >> Hi Ard, apologies for annoying! >> > > No worries, just very busy :-) > >> Just a friendly ping asking if you have any opinions about these patches. >> > > Honestly, I'm not sure I see the value of this. You want to 'notify > the UEFI firmware' but the firmware doesn't really care about these > variables, only your bespoke tooling does. EFI pstore captures far > more data, so if you just wipe /sys/fs/pstore after each clean boot, > you already have all the data you need, no? > > Also, I'm in the process of removing the public efivar_entry_xxx() API > - please look at the efi/next tree for a peek. This is related to your > point 3), i.e., the efivar layer is a disaster in terms of consistency > between different observers of the EFI variable store. Switching to > efivar_set_variable() [the new API] should fix that. Hi Ard, thanks a lot for your review! Lemme split my points in some bullets below: a) What about patch 1, is it good as-is? b) Cool about efivar_set_variable(), could fix that in V2. c) Now, to the most relevant thing, the value of this. I might be mistaken, but is there any known way to let UEFI know a panic happened? For now, maybe only my UEFI fw might use that (and the usage is very nice, showing a panic logo), but this opens a myriad of potential uses. We can think in RAM preserving mechanism conditional to panic scenarios, special resets for panic vs. cold boot, and even maybe a firmware vmcore capturing. If there is any other way to let UEFI know about a panic, let me know and that will likely be more than enough for me. Otherwise, do you think such small code would be a big burden to carry, considering the cost/benefit for my use case? Thanks in advance for your analysis. Cheers, Guilherme
