On Wed, Nov 02, 2011 at 08:49:27PM +0200, Sasha Levin wrote: > This is a proposal for a new layout of the virtio-pci config space. > > We will separate the current configuration into two: A virtio-pci common > configuration and a device specific configuration. This allows more flexibility > with adding features and makes usage easier, specifically in cases like the > ones in virtio-net where device specific configurations depend on device > specific features. > > The preferred location of the configuration will be a MMIO BAR, therefore > several size optimizations such as the queue selector which were useful > on a PIO BAR were removed and linked lists were introduced to add > flexibility to existing structures in attempt to keep their size and > offsets constant and not dependent on features. > > While this is not a complete specification, it describes all the main > structures and should be enough to make sure the idea is solid before > going into implementation specifics. > > A new virtio-pci capability structure will be introduced. This structure > will be used to describe the basics of a virtio-pci device. The > structure is actually a PCI capability structure which wraps the new virtio-pci > capability structure: > > +------------++------------+------------+------------+--------------+----------------- > | Bits || 8 | 8 | 8 | 8 | Cap specific > +------------++------------+------------+------------+--------------+----------------- > | Read/Write || R | R | R | R | Cap specific > +------------++------------+------------+------------+--------------+----------------- > | Purpose || Capability | Capability | virtio-pci | virtio-pci | Cap specific > | || ID | Next PTR | Cap ID | Next Cap PTR | > +------------++------------+------------+------------+--------------+----------------- > > Currently, only one virtio-pci capability is defined, and is the one that defines > the layout of the virtio-pci config space. > > VIRTIO_PCI_C_LAYOUT: > > +------------++---------------+---------------+-----------------+-----------------+ > | Bits || 29 | 3 | 29 | 3 | > +------------++---------------+---------------+-----------------+-----------------+ > | Read/Write || R | R | R | R | > +------------++---------------+---------------+-----------------+-----------------+ > | Purpose || Common config | Common config | Device specific | Device specific | > | || Offset | BIR | Offset | BIR | > +------------++---------------+---------------+-----------------+-----------------+ I'm implementing a different layout, with separate capabilities for common and device specific fields. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
