Re: cciss update for 2.4.24-pre1, #3

From: Marcelo Tosatti
Date: Fri Dec 19 2003 - 11:38:30 EST




On Wed, 17 Dec 2003 mikem@xxxxxxxxxxxxxxxxxxxxxxx wrote:

> Sorry I forgot to send this fix in with the 2 patches I submitted
> yesterday. We found a bug in the ASIC used on the 64xx Smart Array
> controllers. When prefetching from host memory we grab an extra 750 or
> so bytes of data. If this occurs on a memory boundary the machine will crash.
> This is primarily an issue on IPF and Alpha systems although it could happen
> on other platforms. Proliant systems are not affected by this bug because
> memory is contiguous and the top 4k of memory is masked off by the system
> firmware. The solution to the problem is to disable SCSI prefetch in the
> controller firmware. This results in a performance hit on x86 during RAID1
> operations. This patch turns on prefetch for x86 based systems only.
> Please consider this patch for inclusion in the 2.4.24 kernel.
> This patch should be applied after the 2 I submitted yesterday. It will
> patch into a fresh tree with offsets.

The other two patches have been included.

Has the prefetching been tested for long? Which kernels have it enabled?

What about 2.6?
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