Re: [Xen-devel] megaraid problem on hp netserver lh6000 - ignorebiostables o.k.

[Stephen Evanchik <evanchsa@xxxxxxxxxxxx>]

On Fri, 2004-02-27 at 09:46, Manfred.Herrmann@xxxxxxxxxx wrote:
> XEN1.2 democd default boot 2.4.25
>    stop at ... megaraid scanning raidchannel with error:
> 
>       scsi0: scanning virtual channel0 for scsi devices.
>       scsi_wait_req: still waiting...!
>       scsi_wait_req: still waiting...!
>       scsi_wait_req: still waiting...!
>       scsi_wait_req: still waiting...!
>       (... endless)


I can also confirm this behavior with a Dell PowerEdge, dual Xeon, 2GB
system with the MPT Fusion (LSI1030) SCSI controller. 

This happens from 'time to time' with the driver I ported way back in
November. I brushed it off as a driver problem as its awful code. Of
course, we do have reports of the thing working quite well with a domain
configured sufficiently.

My machine is well within the specs too ;) 

This machine has 3 SCSI controllers (aic79xx, sym83cxx_2 and the
mptfusion) and I think I only see the above when there is a drive
plugged in to the mptfusion controller. 

I do have a spark of a memory creating a patch that timed out in
scsi.c:scsi_wait_req because this appeared with _NO_ drives attached and
the driver enabled.

Actually, the more I think about it the more I remeber that when this
happened something strange was going on with the DMA for the
request/reply frames.. and a quick check of some debug output confirms
that.

When this happens with the MPT Fusion controller you see this in the
initialization and subsequent commands:

http://www.clarkson.edu/~evanchsa/xen/debug/dma.txt

and then later that day I made changes to get this:

http://www.clarkson.edu/~evanchsa/xen/debug/dma.111003.txt

I now recall that I got rid of some of their PCI handling code as it was
no longer needed in the newer kernels. I think that was the change I
mentioned above. 



I could be completely wrong of course ;) I'm not a pro at this by any
means.



The machine is currently being used so I'll have to schedule some time
to check in to this more.



Stephen



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