On 19.07.2017 15:03, Cornelia Huck wrote: > On Tue, 18 Jul 2017 16:24:46 +0200 > Cornelia Huck <coh...@redhat.com> wrote: > >> Next try of the zPCI detangling, taking cpu models into account. >> >> The goal of this is twofold: >> - Being able to disable PCI support in a build completely, as for v1. >> - Properly fencing off PCI if the relevant facility bit is not provided. >> >> The second one leads to an interesting usability problem: -device help >> still shows the various pci devices, but you cannot add them if the >> cpu model does not include zpci, due to the phb not being instantiated. >> The user is presented with >> >> qemu-system-s390x: -device virtio-rng-pci: No 'PCI' bus found for device >> 'virtio-rng-pci' >> >> ...which is not very helpful, as it does not point to the root cause (no >> zpci in the cpu model, and therefore no pci at all). Not sure how one can >> communicate this root cause, ideas welcome. > > An idea on how to improve this would still be welcome :)
IMHO it's ok to keep that error message ... but we should add a section to http://wiki.qemu.org/Documentation/Platforms/S390X about PCI devices, including a sample error message as above and a note what has to be done to get a machine with PCI support, so that people can find that page via Google in case they run into this problem. Thomas