Re: [PATCH 1/2] efi: Make 'efi_enabled' a function to query EFIfacilities

[Matt Fleming]

On Mon, 2013-01-21 at 14:42 -0600, H. Peter Anvin wrote:
> On 01/21/2013 02:40 PM, Matt Fleming wrote:
> > From: Matt Fleming <matt.fleming@xxxxxxxxx>
> > 
> > Originally 'efi_enabled' indicated whether a kernel was booted from
> > EFI firmware. Over time its semantics have changed, and it now
> > indicates whether or not we are booted on an EFI machine with
> > bit-native firmware, e.g. 64-bit kernel with 64-bit firmware.
> > 
> > But users actually want to query 'efi_enabled' for different reasons -
> > what they really want access to is the list of available EFI
> > facilities.
> > 
> > For instance, the x86 reboot code needs to know whether it can invoke
> > the ResetSystem() function provided by the EFI runtime services, while
> > the ACPI OSL code wants to know whether the EFI config tables were
> > mapped successfully. There are also checks in some of the platform
> > driver code to simply see if they're running on an EFI machine (which
> > would make it a bad idea to do BIOS-y things).
> > 
> 
> Could you please explain as part of the checkin comment why this is
> needed for urgent/stable?  I.e. what breaks *now*, as opposed to this
> being a cleanup for the next merge window.

Sure thing. Included here,

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