Re: [libvirt] [PATCH v3 09/12] qemu: Generate and use zPCI device in QEMU command line

On Wed, 2018-08-22 at 11:06 +0800, Yi Min Zhao wrote: > 在 2018/8/20 下午7:14, Andrea Bolognani 写道: >> So which is unique: uid, fid, or the combination of the two? >> Could I have >> >> -device zpci,uid=1,fid=1 >> -device zpci,uid=1,fid=2 >> >> or would that not work? What about >> >> -device zpci,uid=1,fid=1 >> -device zpci,uid=2,fid=1 >> >> would that be okay? > Both can't work. FID must be unique and UID must be also unique. > They are independent. Got it, thanks. >> My point is that a funtion called fooIsBaz() should only ever >> check whether the foo in question is indeed a baz, without taking >> any other action such as reporting errors. Leave that to the >> caller, or give the function a different name. > I think moving to the caller is proper. > >> qemuDomainDeviceDefValidate() looks like a reasonable entry point >> for checks such as "you specified a zPCI address but this is not >> an s390 guest" or "your configuration requires zPCI but the QEMU >> binary doesn't support that feature". Both of the cases above >> should have proper test suite coverage, by the way. > How about my idea mentioned above? You mean moving the check to the caller?

I think qemuDomainDeviceDefValidate() is a better choice because it should allow you to implement the checks once, potentially with more context such as information about the domain and QEMU capabilities, and have them performed regardless of whether the device is being processed eg. during regular parsing or hotplug.