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

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Date:	Fri, 04 Jan 2013 09:42:54 -0700
From:	Tim Gardner <rtg.canonical@...il.com>
To:	Matt Fleming <matt@...sole-pimps.org>
CC:	Steve Langasek <steve.langasek@...onical.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
	"H. Peter Anvin" <hpa@...or.com>, Olof Johansson <olof@...om.net>,
	Tony Luck <tony.luck@...el.com>,
	David Airlie <airlied@...ux.ie>,
	Corentin Chary <corentincj@...aif.net>,
	Dave Jiang <dave.jiang@...el.com>,
	Peter Jones <pjones@...hat.com>,
	Konrad Rzeszutek Wilk <konrad@...nel.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>, tim.gardner@...onical.com
Subject: Re: [RFC PATCH 1/2] efi: Make 'efi_enabled' a function to query EFI
 facilities

On 01/04/2013 09:15 AM, Matt Fleming wrote:
> On Fri, 2013-01-04 at 08:08 -0700, Tim Gardner wrote:
>> On 01/03/2013 06:18 AM, Matt Fleming wrote:
>>> From: Matt Fleming <matt.fleming@...el.com>
>>>
>>
>> snip
>>
>>>   /*
>>> - * We play games with efi_enabled so that the compiler will, if possible, remove
>>> - * EFI-related code altogether.
>>> + * We play games with efi_enabled so that the compiler will, if
>>> + * possible, remove EFI-related code altogether.
>>>    */
>>> +#define EFI_BOOT		0x00000001 /* Were we booted from EFI? */
>>> +#define EFI_SYSTEM_TABLES	0x00000002 /* Can we use EFI system tables? */
>>> +#define EFI_CONFIG_TABLES	0x00000004 /* Can we use EFI config tables? */
>>> +#define EFI_RUNTIME_SERVICES	0x00000004 /* Can we use runtime services? */
>>> +#define EFI_MEMMAP		0x00000008 /* Can we use EFI memory map? */
>>> +#define EFI_64BIT		0x00000010 /* Is the firmware 64-bit? */
>>> +
>>
>> Your use of test_bit() and set_bit() imply that these macros should be
>> bit numbers, not bit masks. It'll work until you define a mask with an
>> integer value greater then 31.
>
> They're not intended to be bitmasks in the sense that no two bits are
> set in each constant (and I am aware of the upper limit).
>
> I have no problem changing the above values to bit numbers if that would
> be less confusing.
>

When you do change them to bit numbers you should also note that 
EFI_CONFIG_TABLES and EFI_RUNTIME_SERVICES have the same value, which I 
believe is in error.

rtg
-- 
Tim Gardner tim.gardner@...onical.com
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