Re: [PATCH v2 7/7] PCI/quirks: Avoid certain address on Genoa systems

[Borislav Petkov]

On Fri, Oct 02, 2026 at 02:33:15PM +0300, Ilpo Järvinen wrote:
> While testing the resource placement changes, tests hit a case where
> igb fails to probe when BAR 0 is placed at 0x9c000000:
> 
>    90000000-9cffffff : PCI Bus 0000:a0
>   -  90000000-902fffff : PCI Bus 0000:a1
>   -    90000000-900fffff : 0000:a1:00.0
>   -      90000000-900fffff : igb
>   -    90100000-901fffff : 0000:a1:00.0
>   -    90200000-90203fff : 0000:a1:00.0
>   -      90200000-90203fff : igb
>   +  9be00000-9c0fffff : PCI Bus 0000:a1
>   +    9be00000-9befffff : 0000:a1:00.0
>   +    9bf00000-9bf03fff : 0000:a1:00.0
>   +    9c000000-9c0fffff : 0000:a1:00.0
>      9c100000-9c17ffff : amd_iommu
>      9c180000-9c1803ff : IOAPIC 8
> 
>   -       Region 0: Memory at 90000000 (32-bit, non-prefetchable) [size=1M]
>   -       Region 3: Memory at 90200000 (32-bit, non-prefetchable) [size=16K]
>   -       Expansion ROM at 90100000 [disabled] [size=1M]
>   +       Region 0: Memory at 9c000000 (32-bit, non-prefetchable) [size=1M]
>   +       Region 3: Memory at 9bf00000 (32-bit, non-prefetchable) [size=16K]
>   +       Expansion ROM at 9be00000 [disabled] [size=1M]
> 
> igb 0000:a1:00.0 0000:a1:00.0 (uninitialized): PCIe link lost
> ------------[ cut here ]------------
> igb: Failed to read reg 0x18!
> WARNING: drivers/net/ethernet/intel/igb/igb_main.c:724 at igb_rd32.cold+0x3c/0x4f [igb], CPU#32: kworker/32:1/706
> ...
>  igb_get_invariants_82575+0xff/0xf00 [igb]
>  igb_probe+0x3c8/0x1190 [igb]
>  local_pci_probe+0x3b/0x80
> 
> It turns out there is a 64kB iomem black hole at 9c000000 that returns

Can we please debug that "It turns out" thing and try to find out what really
is going on here.

Can you pls explain what your machine looks like so that we can try to
reproduce it and see what's going on?

Does it have latest BIOS, microcode, etc etc? If it doesn't, can you upgrade
and try again?

I guess dmesg, hwinfo, kernel .config would be good starters, privately is
fine too.

Thx.

-- 
Regards/Gruss,
    Boris.

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