Re: [PATCH 09/21] hw/arm/fsl-imx8mp: Add PCIe support

[Bernhard Beschow]

Am 28. Januar 2025 14:33:14 UTC schrieb Peter Maydell 
<peter.maydell@linaro.org>:
>On Mon, 20 Jan 2025 at 20:38, Bernhard Beschow <shentey@gmail.com> wrote:
>>
>> Linux checks for the PLLs in the PHY to be locked, so implement a model
>> emulating that.
>>
>> Signed-off-by: Bernhard Beschow <shentey@gmail.com>
>
>> diff --git a/docs/system/arm/imx8mp-evk.rst b/docs/system/arm/imx8mp-evk.rst
>> index 1514bc5864..8d48580cb4 100644
>> --- a/docs/system/arm/imx8mp-evk.rst
>> +++ b/docs/system/arm/imx8mp-evk.rst
>> @@ -14,6 +14,7 @@ The ``imx8mp-evk`` machine implements the following 
>> devices:
>>   * Generic Interrupt Controller (GICv3)
>>   * 4 UARTs
>>   * 3 USDHC Storage Controllers
>> + * 1 Designware PCI Express Controller
>>   * Secure Non-Volatile Storage (SNVS) including an RTC
>>   * Clock Tree
>>
>> @@ -62,3 +63,15 @@ Now that everything is prepared the newly built image can 
>> be run in the QEMU
>>        -dtb imx8mp-evk-patched.dtb \
>>        -append "root=/dev/mmcblk2p2" \
>>        -drive file=sdcard.img,if=sd,bus=2,format=raw,id=mmcblk2
>> +
>> +Using PCI Devices
>> +-----------------
>> +
>> +The PCI Express controller spawns two PCI buses, of which only one can be 
>> used.
>> +By default QEMU assigns the wrong bus, so the correct one has to be 
>> specified
>> +manually by adding ``bus=dw-pcie``. For example, when adding an Intel e1000
>> +network card, the command line looks like:
>> +
>> +.. code-block:: bash
>> +
>> +  $ qemu-system-aarch64 -M imximp-evk ... -device virtio-net-pci,bus=dw-pcie
>
>Why does this happen? Isn't there some way to make QEMU default to
>using the right bus? Otherwise there's likely to be a lot of
>user confusion because PCI "doesn't work"...

Yeah, this is really confusing and I forget about it myself. I'd appreciate any 
hints here.

Best regards,
Bernhard

>
>thanks
>-- PMM