Comment 163 for bug 1040557

Hi Steve/CluedInDevs,

NOTE: I haven't really looked at ACPI and UEFI till date. Only today I have done some initial glance thro UEFI and done some code browsing. So may be I am off by 100 miles, correct me if that is the case.

One thing which I haven't fully cross checked/figured yet is how EFI variable storage is linked to crash dumps. Because I don't see a direct usage of efi variable storage in the kernel code wrt crash dumping.

However there is the ACPI ERST based pstore mechanism. Is it that the ACPI ERST inturn uses EFI variable storage in a UEFI system. Logically it seems very much possible and a proper solution wrt the firmware perspective. However in that case I am not 100% sure that passing noefi will ensure that ACPI erst mechanism wont trigger efi variable storage or other runtime services. Is it that because by passing noefi we are stopping the setting up of proper virtual address mapping for the efi systable related entries, so even if ACPI erst mechanism were to trigger variable storage write, it won't succeed ????? i.e is it that we will be depending on a indirect luck to stop the variable storage write triggering during kernel crash ?

If it is a indirect luck based chance that we are stopping variable storage write during kernel crash dump when noefi is used, then rather we may have to ideally have additional logic added to stop registering of acpi erst pstore when noefi is passed (or when a new boot param like fullsystem_noefi is passed).