Re: DMA problem (?) w/ 2.4.6-xfs and ServerWorks OSB4 Chipset

[Adam McKenna]

On Tue, Nov 13, 2001 at 09:51:21AM +0000, Alan Cox wrote:
> > I ask because I'm still having major problems with the OSB4 chipset on
> > 2.4.14.  I've had to disable DMA completely on my boxes to avoid IDE errors
> > and fs corruption.  Does anyone know of a patch that addresses the issues
> > with this chipset?
> 
> No. I spent some time digging into this problem with both Serverworks and
> Red Hat customers. With certain disks, certain OSB4 revisions and UDMA 
> the controller occasionally gets "stuck", the next DMA it issues starts
> by reissuing the last 4 bytes of the previous request and the entire thing
> goes totally to crap.
> 
> The -ac tree will detect this case and panic and hang the machine solid to
> avoid actual disk corruption. The real fix appears to be "dont do UDMA on
> the OSB4". The CSB5 seems fine.

I am having problems with both UDMA and Multiword DMA.  The problem doesn't
go away unless I disable CONFIG_IDEDMA_PCI_AUTO.

I don't know if there is actual FS corruption with MWord DMA, but there is
definitely a "hang" for a few seconds accompanied by a DMA error.

--Adam

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