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Re: [Qemu-devel] Linux 2.6.21 doesn't work with qemu-arm SCSI controller

From: Rob Landley
Subject: Re: [Qemu-devel] Linux 2.6.21 doesn't work with qemu-arm SCSI controller anymore.
Date: Fri, 6 Jul 2007 15:09:19 -0400
User-agent: KMail/1.9.6

On Tuesday 26 June 2007 10:41:32 andrzej zaborowski wrote:
> On 07/06/07, Rob Landley <address@hidden> wrote:
> > In the 2.6.21 kernel the sym53c8xx_2 SCSI controller changed in a way
> > that QEMU's virtual SCSI controller doesn't handle this properly:
> I spent some time yesterday trying to find out what was happening and
> the results are below.
> QEMU's virtual SCSI controller does handle it properly and the kernel
> sym53c8xx_2 driver changes are not at fault.
> The first surprising fact, and one which took me long to figure out,
> was that all the SCSI errors are a result of a case of simple
> interrupts from the controller not reaching the SCSI driver, hence the
> timeouts and whatnot. The sym53c8xx_2 driver gets irq 0 instead of 27,
> from the tiwsted PCI irq number assignment logic. This was because the
> VersatilePB PCI driver was reading the irq pin number from a wrong
> address in the scsi controller's (which is a pci device) config
> structure, and the read always returned a 0 which normally means that
> the device uses no interrupts (actually all 8-bit accesses were
> broken). I corrected the versatile PCI code and sent a patch to linux.
> However, the funny part is that this code had not changed since
> 2.6.18, so how did it break in 2.6.21? Well, it was broken all the
> time, but there was a bug in generic PCI code in
> drivers/pci/setup-irq.c, which effectively caused the value read from
> the device's supplied config, to be discarded, which got fixed in
> 2.6.21.
> If you definitely must use 2.6.21, this qemu workaround also works
> (need to do the same for any other PCI device you want to use):

I got the Linux kernel patch from the ARM guys:

Confirmed it fixed it for me, and pestered the kernel guys in hope this gets 
into 2.6.22.


"One of my most productive days was throwing away 1000 lines of code."
  - Ken Thompson.

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