linux-kernel - Re: Word-at-a-time dcache name accesses

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Message-ID: <m2eht964ud.fsf@firstfloor.org>
Date:	Sat, 03 Mar 2012 08:12:42 -0800
From:	Andi Kleen <andi@...stfloor.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Al Viro <viro@...iv.linux.org.uk>
Subject: Re: Word-at-a-time dcache name accesses

"H. Peter Anvin" <hpa@...or.com> writes:

> On 03/02/2012 03:46 PM, Linus Torvalds wrote:
>> 
>> Comments?
>> 
>
> My biggest concern is what happens when this happens to be at the end of
> mapped kernel memory and we overrun the page?

A long time ago (AMD K7ish) we had hardware bugs to work around in
this area. Overlapping into some PCI hole MMIO areas could cause obscure
hangs.  That is why I was always careful to not do that in any x86
library code.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only
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