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

From: H. Peter Anvin
Date: Mon Jan 21 2013 - 15:42:37 EST


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.

-hpa


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