Re: Celistica with AMD chip-set

[Richard B. Johnson]

On Mon, 30 Aug 2004, Andi Kleen wrote:

> Alan Cox <alan@xxxxxxxxxxxxxxxxxxx> writes:
>
> > On Llu, 2004-08-30 at 15:02, Richard B. Johnson wrote:
> >> Hello all,
> >>
> >> The Celistica server with the AMD chip-set has very poor
> >> PCI performance with Linux (and probably W$ too).
> >>
> >> The problem was traced to incorrect bridge configuration
> >> in the HyperTransport(tm) chips that connect up pairs
> >> of slots.
>
> >    while((pdev = pci_find_device(0x1022, 0x7450, pdev)) != NULL)
> >        pci_write_config_dword(pdev,  0x4c, 0x2ec1);
>
>
> > Can you get Celestica to mail me their PCI subvendor
> > id/devid's for the problem configuration or DMI strings
> > and then we can do a PCI quirk properly for this.
>
> Celistica is just the contract manufacturer for the AMD
> reference design, they're really AMD designs. 0122/7450
> is the AMD 8131 PCI-X bridge.
>
> I doubt it is a good idea to blindly change the configuration of the
> bridge like this in the kernel.  It is probably better to wait for an
> BIOS update or if you really need an urgent fix to do it from user
> space. Any fix should probably read/change bit/write the register, not
> blindly overwrite.
>
> -Andi
>
It is NOT "blindly" overwritten. We know what was in that register
(0x2c01).

Also, it is a "fix" for those who are getting crappy performance
from their boxes. Hopefully a new BIOS will be out with more
permanent fixes.


Cheers,
Dick Johnson
Penguin : Linux version 2.4.26 on an i686 machine (5570.56 BogoMips).
            Note 96.31% of all statistics are fiction.

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