On Thu, 18 Oct 2007, David Miller wrote:

quoted text
> From: "Shane Huang" <Shane.Huang@amd.com>
> Date: Thu, 18 Oct 2007 18:37:59 +0800
> 
> > Hi Miller:
> > 
> > Thank you for your response.
> > 
> > The reason why MSIs of these northbridges do not work is still under
> > further debug, we are NOT able to tell its hardware issue or software
> > issue at this  time. But enablement of them will lead to the OS
> > installation failure in many distributions like openSUSE, Ubuntu etc:
> > https://bugzilla.novell.com/show_bug.cgi?id=302016
> > 
> > So we have to disable them firstly before we find out the root cause,
> > maybe they are just workarounds.
> 
> This logic seems backwards, to me.  "shoot first, ask questions later"
> To me this it not how to approach this problem.
> 
> Once you turn MSI off, there is next to no incentive to fix the
> problem because users aren't running into it any longer.
> 
> The only two devices in that bug report which should be using MSI
> would be the SATA controller and the broadcom ethernet NIC.  And by
> the failed bootup logs provided by the user the problem is clearly
> with the SATA controller.

And the same SATA controller could show up behind a different northbridge. 
It would be unfortunate to hit the same device bug independantly on each 
system and work around it by doing something that won't help the next 
user.

quoted text
> One common problem we're finding is that some devices have a hardware
> bug where setting INTX_DISABLE in the PCI COMMAND register masks MSI
> interrupts too.
> 
> I mention this because the user in that report mentions that the
> kernel upgrade causes the failure, and one thing we started doing not
> too long ago was to set the INTX_DISABLE bit when MSI is enabled for a
> device.
> 
> So maybe this SATA controller has this problem too.  It is easy to
> test, simply comment out all of the pci_intx() function calls in
> drivers/pci/msi.c and perform a test boot with MSI enabled.

Have we gotten around to having a device quirk for this? I bet it won't be 
too long before we see a system where the SATA controller doesn't work 
with INTX disabled and the ethernet controller doesn't work with it 
enabled, since we've seen devices with each of these bugs.

	-Daniel
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