On Wed, 2011-11-23 at 10:49 +0200, Michael S. Tsirkin wrote: > On Wed, Nov 23, 2011 at 01:02:22PM +1030, Rusty Russell wrote: > > +/* Fields in VIRTIO_PCI_CAP_COMMON_CFG: */ > > +struct virtio_pci_common_cfg { > > + /* About the whole device. */ > > + __u64 device_features; /* read-only */ > > + __u64 guest_features; /* read-write */ > > We currently require atomic accesses to common fields. > Some architectures might not have such for 64 bit, > so these need to be split I think ... We can consider stealing the feature implementation from virtio-mmio: Use the first 32 bits as a selector and the last as the features themselves. It's more complex to work with, but it provides 2**32 32 feature bits (which should be enough for a while) and it solves the atomic access issue. > > + __u64 queue_address; /* read-write */ > > + __u16 msix_config; /* read-write */ > > + __u8 device_status; /* read-write */ > > + __u8 unused; > > + > > + /* About a specific virtqueue. */ > > + __u16 queue_select; /* read-write */ > > + __u16 queue_align; /* read-write, power of 2. */ > > + __u16 queue_size; /* read-write, power of 2. */ > > + __u16 queue_msix_vector;/* read-write */ > > +}; > > #endif > > > > -- Sasha. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization