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Re: [PATCH] TX49 MFC0 bug workaround

To: Atsushi Nemoto <>
Subject: Re: [PATCH] TX49 MFC0 bug workaround
From: Sergei Shtylylov <>
Date: Fri, 03 Feb 2006 05:12:47 +0300
Cc: Linux MIPS <>
In-reply-to: <>
Organization: MontaVista Software Inc.
Original-recipient: rfc822;
References: <> <> <>
User-agent: Mozilla/5.0 (X11; U; Linux i686; rv:1.7.2) Gecko/20040803

Atsushi Nemoto wrote:

On Thu, 02 Feb 2006 21:46:25 +0300, Sergei Shtylylov <> 

If mfc0 $12 follows store and the mfc0 is last instruction of a
page and fetching the next instruction causes TLB miss, the result
of the mfc0 might wrongly contain EXL bit.

sshtylyov>     Hmm, a TLB miss in fetching from KSEG0?!

We can call these inline functions from modules running on KSEG2.

   Hm, I'm still learning Linux/MIPS, and have overlooked #ifdef MODULE. :-<

If I don't mistake, the offending code is in local_irq_disable, local_irq_save, and local_irq_restore macros. The effect would be a crash on any exception taken once interrupts get disabled in a module (*and* that code happens to fall on a page boundary)... nasty. :-(

Atsushi Nemoto

WBR, Sergei

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