[edk2-devel] [PATCH v4 7/9] OvmfPkg/PciHostBridgeUtilityLib: Extend parameter list of GetRootBridges

[Laszlo Ersek]

On 01/14/21 13:44, Jiahui Cen wrote:
> On 2021/1/14 18:46, Laszlo Ersek wrote:

>> (7) You missed replacing PCI_MAX_BUS with BusMax here. (But it belongs
>> in the separate patch that will deal with the bus numbers, and only with
>> the bus numbers.)
>>
>> ... Which in turn makes me ask you to please test your changes more
>> carefully. I believe this bug here is actually shown in the firmware
>> debug log. Namely, the "virt" machine type only supports buses 0x0..0xf,
>> inclusive (if I remember correctly), because its MMCONFIG space is quite
>> limited.
>>
> 
> I tested on QEMU for x86_64 and aarch64, and it actually worked well so that
> I missed this issue. IIUC, for aarch64, the virt machine supports bus range
> [0x0, 0xff] by default, and the MMCONFIG space size is 256MB.

Thanks for the reminder -- now I remember this MMCONFIG size depends on
the "highmem" machine type property. Indeed it should be "on" for
aarch64 by default; it's still "off" for 32-bit ARM (and ArmVirtQemu
supports 32-bit ARM as well).

Thanks
Laszlo



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