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From: Matthew Wilcox <willy@debian.org>
To: Joel Soete <soete.joel@tiscali.be>
Cc: Matthew Wilcox <willy@debian.org>,
	Derek Engelhaupt <derekengelhaupt@rocketmail.com>
Subject: Re: [parisc-linux] L2000/N4000 smp devices/boot compare??
Date: Fri, 3 Oct 2003 12:49:59 +0100	[thread overview]
Message-ID: <20031003114959.GM24824@parcelfarce.linux.theplanet.co.uk> (raw)
In-Reply-To: <3F704CAF0000522B@ocpmta2.freegates.net>

On Fri, Oct 03, 2003 at 08:15:03AM +0200, Joel Soete wrote:
> Derek, Matthew,
> 
> Thanks a lot for those clarification.
> As I try, without any success :(, to find where 'rules for non-coherent aliases'
> are not respected, I will waiting for a fix.

Well, it's hard.  Consider a page in the page cache.  It has a kernel
address and one-or-more user addresses.  The user addresses all follow the
coherency rules but the kernel address doesn't.  If you look in Appendix F,
we're not allowed to have multiple write-capable translations to the same
address.

I think the only way to solve this is by (ab)using kmap to ensure that
kernel pages are only accessed via coherent mappings.

-- 
"It's not Hollywood.  War is real, war is primarily not about defeat or
victory, it is about death.  I've seen thousands and thousands of dead bodies.
Do you think I want to have an academic debate on this subject?" -- Robert Fisk

  parent reply	other threads:[~2003-10-03 12:12 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-10-02 16:53 [parisc-linux] L2000/N4000 smp devices/boot compare?? Joel Soete
2003-10-02 23:38 ` Derek Engelhaupt
2003-10-03  0:18   ` Matthew Wilcox
     [not found]     ` <3F704CAF0000522B@ocpmta2.freegates.net>
2003-10-03 11:49       ` Matthew Wilcox [this message]
2003-10-14 16:59         ` Joel Soete
2003-10-15  4:52           ` Grant Grundler
2003-10-15  6:02             ` Joel Soete
2003-10-06 14:31     ` Grant Grundler
     [not found] <3F8A29A2000021FB@ocpmta1.freegates.net>
     [not found] ` <20031017023038.GA12379@colo.lackof.org>
     [not found]   ` <3F9193E7.9010504@tiscali.be>
     [not found]     ` <20031018220048.GC10704@colo.lackof.org>
2003-10-18 23:30       ` Joel Soete

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