Hi tglx,

On 11/25/20 12:54 PM, Thomas Gleixner wrote:
> Stefan,
> 
> On Wed, Sep 16 2020 at 12:12, Stefan Bühler wrote:
> 
> sorry for the delay. This fell through the cracks.
> 
>> this quirk breaks our serial ports PCIe card (i.e. we don't see any 
>> output from the connected devices; no idea whether anything we send 
>> reaches them):
>>
>> 05:00.0 PCI bridge: PLX Technology, Inc. PEX8112 x1 Lane PCI Express-to-PCI Bridge (rev aa)
>> 06:00.0 Serial controller: Oxford Semiconductor Ltd OX16PCI954 (Quad 16950 UART) function 0 (Uart)
>> 06:00.1 Bridge: Oxford Semiconductor Ltd OX16PCI954 (Quad 16950 UART) function 0 (Disabled)
>> 06:01.0 Serial controller: Oxford Semiconductor Ltd OX16PCI954 (Quad 16950 UART) function 0 (Uart)
>> 06:01.1 Bridge: Oxford Semiconductor Ltd OX16PCI954 (Quad 16950 UART)
>> function 0 (Disabled)
> 
> Can you please provide the output of:
> 
>  for ID in 05:00.0 06:00.0 06:00.1 06:01.0 06:01.1; do lspci -s $ID -vvv; done
> 

See attachment.

Also I boot the affected systems now with "pci=noioapicquirk", which
"solves" the issue too (instead of patching the kernel).

cheers,
Stefan