linux-kernel - Re: [git pull] x86 fixes

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Message-ID: <871w1mj63p.fsf@saeurebad.de>
Date:	Tue, 22 Jul 2008 17:23:06 +0200
From:	Johannes Weiner <hannes@...urebad.de>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [git pull] x86 fixes

Hi,

Jeremy Fitzhardinge <jeremy@...p.org> writes:

> Johannes Weiner wrote:
>> Hi,
>>
>> Ingo Molnar <mingo@...e.hu> writes:
>>
>>   
>>> Linus,
>>>
>>> Please pull the latest x86 fixes git tree from:
>>>
>>>    git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git x86-fixes-for-linus
>>>
>>> Thanks,
>>>
>>> 	Ingo
>>>
>>> ------------------>
>>> Jan Kratochvil (1):
>>>       x86: fix crash due to missing debugctlmsr on AMD K6-3
>>>
>>> Jeremy Fitzhardinge (2):
>>>       x86: rename PTE_MASK to PTE_PFN_MASK
>>>       x86: add PTE_FLAGS_MASK
>>>     
>>
>> Are you serious?  It goes _this_ fast?  The patch came into my mbox at
>> 8:00am this morning and you push it to Linus at 4:00pm already?
>>
>> What about the inconsistency it introduces?  When I look at PAGE_MASK
>> for example, it masks out the PAGE offset.  PTE_MASK masks out PTE
>> specifca from a value.
>>
>> Now, I assume PTE_PFN_MASK masks out the PFN.  Oh, wait, it masks the
>> protection bits.
>
> PAGE_MASK turns an address into its page address.
>
> PTE_PFN_MASK takes a pte value and returns the pte's pfn portion
> (which is shifted so it's actually a page address).

Okay, now it makes sense.

I just always thought of PAGE_MASK as `mask out sub-page granularity'.

> In both cases, the X_MASK terminology means that X is extracted, not
> excluded.  Which makes sense; if you have a packed bitfield containing
> multiple values, you wouldn't expect X to be the list of things *not*
> extracted.

Agreed.

	Hannes
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