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Re: Tester with IP27/IP30 needed

To: Kumba <>
Subject: Re: Tester with IP27/IP30 needed
From: Thiemo Seufer <>
Date: Tue, 5 Feb 2008 12:22:11 +0000
Cc: Florian Lohoff <>, Ralf Baechle <>, Thomas Bogendoerfer <>,,
In-reply-to: <>
Original-recipient: rfc822;
References: <> <> <> <> <> <> <> <> <> <>
User-agent: Mutt/1.5.17+20080114 (2008-01-14)
Kumba wrote:
> Florian Lohoff wrote:
>> On Sun, Feb 03, 2008 at 03:16:48AM +0100, Ralf Baechle wrote:
>>> On Sat, Feb 02, 2008 at 05:08:31PM -0500, Kumba wrote:
>>>> Thomas Bogendoerfer wrote:
>>>>> no suprise here. As Ralf already noted cache barrier is a restricted
>>>>> instruction, it will always cause a illegal instruction when used
>>>>> in user space. Nevertheless it looks like all IP28 are affected
>>>>> by the simple exploit. Flo built glibc 2.7 with LLSC war workaround
>>>>> and this avoids triggering the hang.
>>>> Ah, didn't know the 'cache' instructions was kernel-mode only.  
>>>> Explains why it survived then :)
>>>> How does one enable the LLSC war workaround in glibc?
>>> By modifying the code ;-)
>> Flo
> Interesting.  Is there a reason the kernel uses an #ifdef to choose 
> between 'bezq' and 'bezql' that's not needed in glibc itself?  Or does 
> glibc itself lack a mechanism to detect CPU types to single out this 
> specific change?

glibc for mips has currently no such mechanism. Note that this change
breaks MIPS I CPUs, so it is not generally applicable.

> And any idea if uClibc will need similar mods?

It needs a similiar change to support R10000 v2.5.


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