Re: [PATCH] pci-quirks: disable MSI on RS400-200 and RS480, take #2

[Jay Cliburn <jacliburn@bellsouth.net>]

Jeff Garzik wrote:
> Chuck Ebbert wrote:
>> Tejun Heo wrote:
>>>> FWIW several distros have turned off MSI by default and added
>>>> a "pci=msi" option to enable it.
>>> Yeah, it seem to cause a lot of problems on certain chips but I think
>>> the correct path is to add PCI quirks for those.  Most MSI problems I've
>>> seen are on these ATI chips.  Do you happen to know any other?
>>
>> We had devices that didn't do MSI right, e.g. forcedeth and others I
>> can't recall now.
> 
> AFAIK that's a broken diagnosis.   It's the system, not the device, that 
> is problematic.
> 

In the case of the Attansic L1 ethernet driver, here's what we see:

chipset			kernel arch	MSI functionality
===============		===========	=================
Intel 945G/ICH7		x86_64		yes
Intel 945G/ICH7		i386		yes
Via K8T890		x86_64		yes
Via K8T890		i386		no

I still don't know why, but we get a flood of APIC errors after starting the 
atl1 driver on a Via K8T890 board (Asus M2V, for example) under a 32-bit kernel, 
and *only* under a 32-bit kernel.

http://lkml.org/lkml/2007/4/8/68

Supporting files and such at ftp://ftp.hogchain.net/pub/linux/m2v/apic-problem

Any hints heartily welcomed...

Jay