On Wed, May 29, 2013 at 10:47:52AM +0930, Rusty Russell wrote: > "Michael S. Tsirkin" <[email protected]> writes: > > > On Mon, Dec 12, 2011 at 01:49:13PM +0200, Michael S. Tsirkin wrote: > >> On Mon, Dec 12, 2011 at 09:15:03AM +1030, Rusty Russell wrote: > >> > On Sun, 11 Dec 2011 11:42:56 +0200, "Michael S. Tsirkin" > >> > <[email protected]> wrote: > >> > > On Thu, Dec 08, 2011 at 09:09:33PM +1030, Rusty Russell wrote: > >> > > > +/* There is no iowrite64. We use two 32-bit ops. */ > >> > > > +static void iowrite64(u64 val, const __le64 *addr) > >> > > > +{ > >> > > > + iowrite32((u32)val, (__le32 *)addr); > >> > > > + iowrite32(val >> 32, (__le32 *)addr + 1); > >> > > > +} > >> > > > + > >> > > > >> > > Let's put addr_lo/addr_hi in the structure then, > >> > > to make the fact this field is not atomic explicit? > >> > > >> > Good point, assuming I haven't missed something. > >> > > >> > Are 64-bit accesses actually unknown in PCI-land? Or is this a limited > >> > availability thing? > >> > > >> > Thanks, > >> > Rusty. > >> > >> I think PCI can optionally support atomic 64 bit accesses, but not all > >> architectures can generate them. > > > > Ping. Going to change this in the layout struct? > > Not sure what you mean.... We use a queue_enable field, so it doesn't > matter if the accesses aren't atomic for that. > > Cheers, > Rusty.
I mean the struct should have separate _lo and _hi fields. Otherwise I have to do: + case offsetof(struct virtio_pci_common_cfg, queue_desc): + assert(size == 4); + return virtio_queue_get_desc_addr(vdev, vdev->queue_sel) & low; + case offsetof(struct virtio_pci_common_cfg, queue_desc) + 4: + assert(size == 4); + return virtio_queue_get_desc_addr(vdev, vdev->queue_sel) >> 32; Would be nicer as: + case offsetof(struct virtio_pci_common_cfg, queue_desc_lo): + assert(size == sizeof cfg.queue_desc_lo); + return virtio_queue_get_desc_addr(vdev, vdev->queue_sel) & low; + case offsetof(struct virtio_pci_common_cfg, queue_desc_hi): + assert(size == sizeof cfg.queue_desc_hi); + return virtio_queue_get_desc_addr(vdev, vdev->queue_sel) >> 32; Agree? -- MST _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
