linux-kernel - Re: [PATCH] arch/tile: new multi-core architecture for Linux

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Date:	Fri, 28 May 2010 13:58:20 -0400
From:	Chris Metcalf <cmetcalf@...era.com>
To:	Marc Gauthier <marc@...silica.com>
CC:	Arnd Bergmann <arnd@...db.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>
Subject: Re: [PATCH] arch/tile: new multi-core architecture for Linux

On 5/27/2010 10:52 AM, Marc Gauthier wrote:
>>> We use [a syscall] not for the floating-point operations, but for integer
>>> divide-by-zero.  In principle we could use it for floating-point too,
>>> but we currently don't, since generally folks don't expect it there.
>>>       
>> Ah, I see. That probably makes a lot of sense to present as a signal
>> the way you do.
>>     
> FWIW, this can also be done using some recognizable illegal
> instruction sequence, if the architecture reserves some opcodes
> as always illegal.

We do reserve a range of illegal values, and this is a great idea.  I've
removed the syscall from our kernel, and will add support for the
appropriate magic in the trap handler once we pick an encoding and give
it a name in the assembler.

-- 
Chris Metcalf, Tilera Corp.
http://www.tilera.com


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