Re: PCI Hotplug ACPI device names only 3 characters long

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

Hi Marcello,

On 5/9/23 17:05, Marcello Sylverster Bauer wrote:
> Greetings,
> 
> I'm currently working on a project to support Intel IPU6 in QEMU via 
> VFIO so that the guest system can access the camera. This requires 
> extending the ACPI device definition so that the guest knows how to 
> access the camera.
> 
> However, I cannot extend the PCI devices because their names are not 4 
> characters long and therefore do not follow the ACPI specification.
> 
> When I use '-acpitable' to include my own SSDT for the IPU6 PCI device, 
> it does not allow me to declare the device as an External Object because 
> it automatically adds padding underscores.
> 
> e.g.
> Before:
> ```
> External(_SB.PCI0.S18.SA0, DeviceObj)
> ```
> After:
> ```
> External(_SB.PCI0.S18_.SA0_, DeviceObj)
> ```

What do you mean by "before" / "after"?

> Adding the underscore padding is hard coded in iASL and also in QEMU 
> when parsing an ASL file. (see: build_append_nameseg())
> 
> So here are my questions:
> 1. Is there a solution to extend the ACPI PCI device using '-acpitable' 
> without having to patch iASL or QEMU?
> 2. Are there any plans to change the names to comply with the ACPI spec? 
> (e.g. use "S%.03X" format string instead)
> 
> Thanks
> Marcello
>