On Tue, Jun 18, 2024 at 07:15:47PM +0900, Shunsuke Mie wrote: > Thank you for your response. > > 2024年6月18日(火) 18:47 Michael S. Tsirkin <mst@xxxxxxxxxx>: > > > > On Tue, Jun 18, 2024 at 08:41:09AM +0900, Shunsuke Mie wrote: > > > Let's clarify the situation. > > > > > > The Virtio device and driver are not working properly due to a > > > combination of the following reasons: > > > > > > 1. Regarding VIRTIO_F_ACCESS_PLATFORM: > > > - The modern spec includes VIRTIO_F_ACCESS_PLATFORM, which allows > > > Physical DMAC to be used. > > > - This feature is not available in the legacy spec. > > > > ... because legacy drivers don't set it > > > > > 2. Regarding Virtio PCIe Capability: > > > - The modern spec requires Virtio PCIe Capability. > > > > It's a PCI capability actually. People have been asking > > about option to make it a pcie extended capability, > > but no one did the spec, qemu and driver work, yet. > > > > > - In some environments, Virtio PCIe Capability cannot be provided. > > > > why not? > PCIe Endpoint Controller chips are available from several vendors and allow > software to describe the behavior of PCIe Endpoint functions. However, they > offer only limited functionality. Specifically, while PCIe bus communication is > programmable, PCIe Capabilities are fixed and cannot be made to show as > virtio's. Okay. So where could these structures live, if not in pci config? -- MST
