Messages in this thread | | | Date | Fri, 14 May 2010 07:54:53 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: [git pull] Input updates for 2.6.34-rc6 |
| |
On Fri, 14 May 2010, Eric W. Biederman wrote: > > efi_enabled is a guard on efi calls. If it is true it tells you that > you can make runtime efi calls. If it is false you can't use runtime > efi calls. efi_enabled does not tell you about the presence of efi > on a system.
We don't really want to know about the "presense". What we want to know about is whether we were _loaded_ with EFI or not.
IOW, even if the system is EFI-capable, if we actually booted through the legacy BIOS interfaces, we would consider ourselves in "legacy" mode.
> All of which means in the normal case pay attention to acpi. That is > more likely to be correct and usable than EFI anything.
Oh yes. ACPI is actually _tested_, so while it's buggy, it's unlikely to be quite as spectacularly buggy as any EFI interfaces probably are.
But the issue here is that on a "legacy PC", we can't just say "ACPI doesn't mention this device, so it can't exist". Because in a legacy PC model, that simply isn't true. All those motherboard devices can easily exist (and do!) even if ACPI/PnP don't mention them.
But if we live in a non-legacy world (ie we were loaded through EFI), I think it's much more reasonable to say "we'll ignore any devices not mentioned by ACPI".
Linus
| |