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Re: [MIPS] Import updates from i386's i8259.c

To: Christoph Hellwig <hch@lst.de>
Subject: Re: [MIPS] Import updates from i386's i8259.c
From: Ralf Baechle <ralf@linux-mips.org>
Date: Thu, 7 Dec 2006 12:33:21 +0000
Cc: linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, mingo@elte.hu
In-reply-to: <20061207094639.GA30260@lst.de>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <S20037871AbWLFUPw/20061206201552Z+14601@ftp.linux-mips.org> <20061207094639.GA30260@lst.de>
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On Thu, Dec 07, 2006 at 10:46:39AM +0100, Christoph Hellwig wrote:

> On Wed, Dec 06, 2006 at 08:15:47PM +0000, linux-mips@linux-mips.org wrote:
> > Author: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Thu Dec 7 02:04:17 2006 +0900
> > Comitter: Ralf Baechle <ralf@linux-mips.org> Wed Dec 6 20:10:54 2006 +0000
> > Commit: bf8cfe1360932f191a3ea8d47c773c008ec32cd7
> > Gitweb: http://www.linux-mips.org/g/linux/bf8cfe13
> > Branch: master
> > 
> > Import many updates from i386's i8259.c, especially genirq transitions.
> 
> Shouldn't we try to share i8259.c over the various architectures that
> use this controller?  With the generic hardirq framework that should be
> possible.

See 
http://www.linux-mips.org/cgi-bin/mesg.cgi?a=linux-mips&i=20061206203259.GA10170%40linux-mips.org
 ;-)

The MIPS version of i8259 is already sharable that is all the code that
doesn't immediately deal with the i8259 PIC has been removed.  A few
small things will need still need attention.  i386 uses this silly
optimization in cached_master_mask / cached_slave_mask that depends on
little endian byte order.  i386 programs ICW2 with 0x20 while MIPS uses
I8259A_IRQ_BASE.  And the i386 version has various stuff such as the FPU
interrupt handler which are not immediately i8259A-related in i8259.c.

  Ralf

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