Hi Shreyansh, First of all, thank you for your work, I was expecting a virtio sound device for some time...
Le 04/05/2021 à 21:35, Shreyansh Chouhan a écrit : > On Tue, 4 May 2021 at 19:02, Laurent Vivier <laur...@vivier.eu > <mailto:laur...@vivier.eu>> wrote: > > There is nothing specific to PCI in that code, why do you prevent the use > of virtio-snd as a MMIO > device? > > I am sorry I do not understand your question completely. If by preventing the > use of virtio-snd, you > mean > why did I add the PCI dependencies to the Kconfig file, then I think I must > have been a bit confused > while writing it. VIRTIO_PCI already includes those dependencies, I will > change the dependency to > VIRTIO. (Which is what it is for other virtio devices too.) > > However if you mean why did I not add an MMIO binding for this device, then > there is no > specific reason. I simply followed what QEMU had been doing for the other > virtio devices. > Will there be any advantages to implementing the device as a MMIO device? No, the question was only about the dependencies, generally a a virtio device is binded to a virtio bus, and virtio PCI is a PCI card providing a virtio bus with the virtio device attached to it. For instance, for virtio-net-pci: HOST -> PCI Host controller -> PCI virtio net device (TYPE_VIRTIO_NET_PCI) -> virtio Bus (TYPE_VIRTIO_BUS) -> virtio net device (TYPE_VIRTIO_NET) TYPE_VIRTIO_NET_PCI is created by hw/virtio/virtio-net-pci.c and TYPE_VIRTIO_NET by hw/net/vrtio-net.c: hw/virtio/meson.build: virtio_pci_ss.add(when: 'CONFIG_VIRTIO_NET', if_true: files('virtio-net-pci.c')) virtio_ss.add_all(when: 'CONFIG_VIRTIO_PCI', if_true: virtio_pci_ss) hw/net/meson.build specific_ss.add(when: 'CONFIG_VIRTIO_NET', if_true: files('virtio-net.c')) hw/net/Kconfig: config VIRTIO_NET bool default y depends on VIRTIO So: the virtio-net device is built when VIRTIO_NET is set, the virtio-net-pci device is build when VIRTIO_NET and VIRTIO_PCI are set. So what I expect for virtio-snd: hw/virtio/meson.build: virtio_pci_ss.add(when: 'CONFIG_VIRTIO_SND', if_true: files('virtio-snd-pci.c')) hw/audio/meson.build: softmmu_ss.add(when: 'CONFIG_VIRTIO_SND', if_true: files('virtio-snd.c')) hw/audio/Kconfig config VIRTIO_SND bool default y depends on VIRTIO With that kind of config, a machine without PCI bus will be able to create a virtio bus to add your virtio device (like s390x with virtio-ccw of any other MMIO machine like the virt machines). In short: update your hw/audio/config, and all will be fine. Thanks, Laurent
