On 27.09.2017 12:59, Christian Borntraeger wrote: > > > On 09/27/2017 12:56 PM, Cornelia Huck wrote: >> On Wed, 27 Sep 2017 18:25:00 +0800 >> Yi Min Zhao <zyi...@linux.vnet.ibm.com> wrote: >> >>> 在 2017/9/27 下午5:47, Cornelia Huck 写道: >>>> On Tue, 26 Sep 2017 20:40:25 +0200 >>>> David Hildenbrand <da...@redhat.com> wrote: >> >>>>> I'd really really really (did I mention really?) favor something like a >>>>> dummy device, because we could easily handle the !CONFIG_PCI case then. >>>>> >>>>> All these compat options and conditions will kill us someday... we're >>>>> already patching around that whole stuff way too much. >>>>> >>>>> If we ever unconditionally created a device, we should keep doing so. >>>> Yes, that whole thing is horrible, especially interaction with compat >>>> machines. >>>> >>>> Do you have an idea on how to create such a dummy device (without >>>> having to effectively copy a lot of configured-out code)? >>>> >>>> >>> How about in s390_pcihost_hot_plug() we check s390_has_feat(zpci)? >>> If no zpci feature, we avoid plugging any pci device. >>> Then we could always create phb. >>> I think pcibus's vmstate is only data to migrate. >> >> That's still problematic if CONFIG_PCI is off. I currently don't have a >> better idea than either disallowing compat machines on builds without >> pci, or using a dummy device... > > For this particular case your initial patch might be less problematic than > a dummy device, because the code that does the migration is NOT contained > in s390 specific code but in common PCI code instead. We would need to keep > the dummy device always in a way that it will work with the common PCI > code. >
Interesting, so how is migration then handled for e.g. x86 or other architectures that can work without CONFIG_PCI? I assume their migration should also break? -- Thanks, David
