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Re: missing flush_dcache_page call in 2.4 kernel

To: phorton@bitbox.co.uk
Subject: Re: missing flush_dcache_page call in 2.4 kernel
From: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Date: Fri, 26 Mar 2004 12:22:58 +0900 (JST)
Cc: linux-mips@linux-mips.org
In-reply-to: <4062F1A1.9070005@bitbox.co.uk>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20040325.224229.112629304.nemoto@toshiba-tops.co.jp> <20040325143319.GA873@linux-mips.org> <4062F1A1.9070005@bitbox.co.uk>
Sender: linux-mips-bounce@linux-mips.org
>>>>> On Thu, 25 Mar 2004 14:50:09 +0000, Peter Horton <phorton@bitbox.co.uk> 
>>>>> said:
>> This seems to be the same problem as reported by Peter Horton as
>> while ago; in his case that was with PIO IDE.
>> 
phorton> Looks like it.

phorton> The fix we're using on Cobalt's at the moment is below
phorton> (required for 2.4.x and 2.6.x).

phorton> Fixing it this way fixes the problem with both page cache
phorton> pages and swap pages.

phorton> For more details see the threads "Kernel 2.4.23 on Cobalt
phorton> Qube2 - area of problem" and "Instability / caching problems
phorton> on Qube 2 - solved ?"  from December last year.

Thanks, I agree (maybe I should read ML messages more carefully ...)

This patch fixes my problem also, thanks, but ... I do not think
r4k_flush_icache_page is a best place to fix since my test program is
not related I-cache at all.

I'm quite sure that it's a kernel bug and may cause problems if any
PIO block device (PIO ide, ide-cs, mtdblock, etc.) are used on CPUs
which have d-cache aliases (not only MIPS).  We need a correct fix ...

---
Atsushi Nemoto

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