linux-kernel - Re: pud_bad vs pud

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Message-ID: <20090205184355.GF5661@elte.hu>
Date:	Thu, 5 Feb 2009 19:43:55 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	William Lee Irwin III <wli@...omorphy.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux Memory Management List <linux-mm@...ck.org>
Subject: Re: pud_bad vs pud_bad


* Jeremy Fitzhardinge <jeremy@...p.org> wrote:

> I'm looking at unifying the 32 and 64-bit versions of pud_bad.
>
> 32-bits defines it as:
>
> static inline int pud_bad(pud_t pud)
> {
> 	return (pud_val(pud) & ~(PTE_PFN_MASK | _KERNPG_TABLE | _PAGE_USER)) != 0;
> }
>
> and 64 as:
>
> static inline int pud_bad(pud_t pud)
> {
> 	return (pud_val(pud) & ~(PTE_PFN_MASK | _PAGE_USER)) != _KERNPG_TABLE;
> }
>
>
> I'm inclined to go with the 64-bit version, but I'm wondering if there's 
> something subtle I'm missing here.

Why go with the 64-bit version? The 32-bit check looks more compact and 
should result in smaller code.

	Ingo
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