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Re: aic7xxx (O2 scsi) DMA coherency

To: Vivien Chappelier <vivien.chappelier@enst-bretagne.fr>
Subject: Re: aic7xxx (O2 scsi) DMA coherency
From: Ralf Baechle <ralf@oss.sgi.com>
Date: Thu, 3 Jan 2002 21:52:15 -0200
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, linux-mips@oss.sgi.com
In-reply-to: <Pine.LNX.4.21.0201032247490.9064-100000@melkor>; from vivien.chappelier@enst-bretagne.fr on Thu, Jan 03, 2002 at 10:51:51PM +0100
References: <E16MFrP-00018Z-00@the-village.bc.nu> <Pine.LNX.4.21.0201032247490.9064-100000@melkor>
Sender: owner-linux-mips@oss.sgi.com
User-agent: Mutt/1.2.5i
On Thu, Jan 03, 2002 at 10:51:51PM +0100, Vivien Chappelier wrote:

> > >   This tells the aic7xxx to use DMA safe memory for I/O.
> > 
> > That seems totally inappropriate. The unchecked dma option is for
> > ancient ISA DMA controllers that didnt do the 16Mb check. If you
> > find you need it debug your pci remapper
> 
> This is used when scaning for devices (drivers/scsi/scsi_scan.c) . When
> this flag is not set, the code uses memory from the stack (unsigned char
> scsi_result0[256]; in scan_scsis) instead of kmallocating it DMA safe as
> it should on non-coherent systems. Maybe this is the thing to change?

Indeed, it is.  I thought this one died ages ago.

  Ralf

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