Celistica with AMD chip-set

Quoted 8 lines · Richard B. Johnson

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.

Quoted 10 lines · Alan Cox

Quoted 8 lines · Richard B. Johnson

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.

Quoted 7 lines

   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).