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Re: aic7xxx (O2 scsi) DMA coherency

To: Alan Cox <>
Subject: Re: aic7xxx (O2 scsi) DMA coherency
From: Vivien Chappelier <>
Date: Fri, 4 Jan 2002 13:30:55 +0100 (CET)
Cc: Ralf Baechle <>,
In-reply-to: <>

On Thu, 3 Jan 2002, Alan Cox 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.

Maybe this is more appropriate then :)
It tells the scsi scanner to always use DMA safe memory when doing its
INQUIRY commands...
On the O2, kernel is running in cacheable, non-coherent memory. kmalloc,
with GFP_DMA flag will return a piece of uncacheable memory which is safe
for I/O with devices.

Vivien Chappelier

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