Re: [Qemu-devel] [PATCH v4 07/10] s390x/sclp: properly guard pci-specific functions

[Cornelia Huck <cohuck@redhat.com>]

On Tue, 22 Aug 2017 11:20:51 +0200
Halil Pasic <pasic@linux.vnet.ibm.com> wrote:

> On 08/22/2017 10:39 AM, Cornelia Huck wrote:
> >> I'm fine either way. If I imagine having a lots of adapter types, then I
> >> would expect a switch or a jumptable on the type before handling control
> >> to the pci specific function. In this case statically not supported types
> >> would probably get caught by the default branch of the switch and for a
> >> jumptable it could even handle the dynamic case (based on the facilities)
> >> trivially. In short both approaches can make sense.  
> > I'm also wondering at the naming (the command sounds very
> > pci-specific). I'd just stick with this approach (modulo a possible
> > change of the response code, for which I need to rely on you guys).
> >   
> 
> 
> Well, the QEMU name of the command is misleading misleading. In the AR
> it's called 'Configure I/O Adapter'. The PCI comes into the picture via
> byte 8 of the SCCB, the so called adapter type. Valid values for the
> adapter type are: 00-01 reserved; 02 PCI function; 03-FF reserved. So
> at this point we only have PCI.

OK, misleading naming combined with missing documentation leads to
confusion...

So:

- s/PCI/IOA/ for SCLP_CMDW_{CONFIGURE,DECONFIGURE}_PCI
- have a switch/case over byte 8 with only one case (pci)
- move the pci feature check into the pci code(? - not sure)

There's still the question of when this sclp command first became
available...