Messages in this thread | | | Subject | Re: [PATCHv3 RFC] virtio-pci: flexible configuration layout | From | Sasha Levin <> | Date | Wed, 23 Nov 2011 11:38:40 +0200 |
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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.
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