Re: [PATCH] hw/s390x: Emit a warning if user tried to enable USB

[Thomas Huth <thuth@redhat.com>]

On 17/10/2019 16.34, Cornelia Huck wrote:
> On Thu, 17 Oct 2019 16:21:23 +0200
> Thomas Huth <thuth@redhat.com> wrote:
> 
>> There is no USB on s390x, so running qemu-system-s390x with
>> "-machine ...,usb=on" is certainly wrong. Emit a warning to make
>> the users aware of their misconfiguration.
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>  After a year or two, we could finally turn this into a hard error,
>>  but I think we should give the users some time to fix their command
>>  lines first, so I'm initially only emitting a warning here.
>>
>>  hw/s390x/s390-virtio-ccw.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
>> index d3edeef0ad..af8c4c0daf 100644
>> --- a/hw/s390x/s390-virtio-ccw.c
>> +++ b/hw/s390x/s390-virtio-ccw.c
>> @@ -243,6 +243,10 @@ static void ccw_init(MachineState *machine)
>>      VirtualCssBus *css_bus;
>>      DeviceState *dev;
>>  
>> +    if (machine->usb) {
>> +        warn_report("This machine does not support USB");
> 
> I'm wondering if this is the only machine type not supporting usb...
> if not, how are others handling it?

I think most machines are silently ignoring it, like we did on s390x
until now, too.

> The usb parsing code in machine.c does not care if usb is even
> configured (CONFIG_USB).

machine.c is common code, so you can not use CONFIG_USB there.

> There's other stuff in there like
> igd-passthru, which seems to be x86 specific; probably historical
> reasons?

IMHO igd-passthru should be moved to the xen machine, which seems to be
the only user.

 Thomas