linux-kernel - Re: bisected boot regression post 2.6.25-rc3.. please revert

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Message-ID: <20080309185752.GA9548@elte.hu>
Date:	Sun, 9 Mar 2008 19:57:52 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Arjan van de Ven <arjan@...ux.intel.com>, hans.rosenfeld@....com,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: bisected boot regression post 2.6.25-rc3.. please revert


* Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> So I would *very* strongly instead argue:
> 
>  - "unsigned long" is the native kernel type for all address manipulation, 
>    and thus "PAGE_SIZE" and "PAGE_MASK" should continue to have that type.
> 
>  - anything that uses any other type without explicitly making sure it's 
>    safe is mis-using those macros. IOW, PAGE_MASk was *never* a type that 
>    had anything what-so-ever to do with page table entry bits, and this is 
>    purely a page table entry issue!
> 
> So my suggested patch would:
> 
>  - make the page table code use a specific mask that it builds up itself, 
>    and makes sure it's of the right type and has the rigth value in 
>    whatever type "struct pte_entry" is. The fact that "pte_val()" is 
>    larger than "unsigned long" on x86-32 is very clearly a PTE issue, 
>    *not* an issue for PAGE_SIZE or PAGE_MASK.

yeah, indeed my patch was sloppy, i didnt think it through - i fell for 
the lure of the easy-looking 'PAGE_SIZE is small, sign-extend it' hack. 

Will do it cleanly and will also clean up all the pte/address/pgprot 
type mixing that currently goes on in this maze of macros.

	Ingo
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