Subject: Re: Mystery packet killing tg3

From: Peter Buckingham <[email-masked]>
Date: Thu, 05 May 2005 12:02:15 -0700

Andi Kleen wrote:
> With iommu=force or CONFIG_IOMMU_DEBUG all IO is foced 
> through the IOMMU.

okay, that's definitely bad...

> Hmm - if you want to hack the kernel you could add udelay()s
> to the no IOMMU paths in arch/x86_64/kernel/pci-gart.c 
> and see if that cures the problem too.  If yes then the timing
> theory would be proved.
> Actually the IOMMU code does more than just delaying, it also
> does config space accesses which might flush or synchronize
> things in the PCI bridges. Perhaps adding some dummy access
> for that would be good too.

okay, i'll start to take a look at this, but it'll probably be a little 
while before i can really get to it. i'll let you know what i find out.

> The dmesg looks similar to the previous one from the IOMMU
> code perspective.

it actually looks like it's configure correctly now (at least from 
agp-gart messages), before we were getting errors. i guess the bios guys 
finally got it right ;-)

thanks,

peter