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From: Kumar Gala <kumar.gala@freescale.com>
Date: Mon, 11 Apr 2005 10:39:20 -0500
To: Dan Malek <dan@embeddededge.com>,
	Fillod Stephane <stephane.fillod@thomson.net>
Cc: linuxppc-dev list <linuxppc-dev@ozlabs.org>
Subject: Re: [PATCH] invalid instructions in kernel mode
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Ok,

After some debug on Friday and this weekend I understand what's going=20
on.  The reason we hit the code path in the kernel is due to the fact=20
that we are actually executing an integer load/store that is=20
misaligned, however when we read the instruction from memory we get a=20
float point instruction.  This is due to the fact that test app is not=20=

properly handling its self generated code.

Note, I was testing with math-emu turned on.

It seems to me that when we introduce CONFIG_PPC_FPU that we ifdef=20
around the code and return 0 in the 44x/e500 cases w/o FPUs

- kumar

On Apr 8, 2005, at 12:36 PM, Fillod Stephane wrote:

> Kumar Gala wrote:
>  > Are you running this via a ramdisk or nfs?=A0 If ramdisk can you =
post=20
> it
>
> > somewhere that I can get to?
>
> I'm running via NFS.
>
> > Also, can you email the list with the kernel oops that shows up.
>
> I'll do that next week.
>
> Anyway, reading the source suffices to realize there's a problem when
> MATH_EMULATION is disabled on a FPU-less system with user programs
> using load/store fp instructions.
>
> --=20
> Stephane