On Sat, Jun 8, 2013 at 7:39 PM, Laszlo Ersek <lersek@xxxxxxxxxx> wrote: > Patches before the last are small cleanups. > > In the last patch I'm trying to extract / generalize an idea from Stefan > Hajnoczi's review of my virtio-net driver for OVMF. > > Unfortunately I can't find Stefan's email on any mailing list archive > (sourceforge, gmane, mail-archive etc. all have only my response), so > I'll quote it here. > > The patch Stefan was reviewing is > <http://thread.gmane.org/gmane.comp.bios.tianocore.devel/2804/focus=2819>: > > [PATCH v3 10/15] > OvmfPkg: VirtioNetDxe: implement Tx: SNP.Transmit and SNP.GetStatus > > On 06/07/13 16:17, Stefan Hajnoczi wrote: > >> There is no read memory barrier between fetching TxCurUsed and >> fetching UsedElem[].Id. In theory I think there is no guarantee that >> Dev->TxRing.Used.UsedElem[UsedElemIdx].Id is fetched *after* >> Dev->TxRing.Used.Idx. On x86 it shouldn't be a problem but I expected >> a read memory barrier after comparing fetching Dev->TxRing.Used.Idx. > > (Solely for the record, my response is at > <http://thread.gmane.org/gmane.comp.bios.tianocore.devel/3052>.) > > In the last patch I'm trying to apply this remark to the virtio spec. > Hopefully I'm not misrepresenting the idea, nor glossing over any > important differences between the VirtioNetDxe code Stefan was actually > reviewing and the example code in the virtio spec. > > I didn't add > > Suggested-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx> > > to the last patch, because my translation may easily have corrupted his > idea, but if the patch is deemed worthwhile, please do add his > Suggested-by. > > > I'm not subscribed to the virtualization list, please keep me CC'd. > > Thanks! > > Laszlo Ersek (5): > Receiving Used Buffers: fix typo in "ring empty" condition in example > code > Receiving Used Buffers: re-disable interrupts when staying in the > loop > Receiving Used Buffers: variable for Queue Size is called "qsz" > elsewhere > Receiving Used Buffers: switch . and -> operators, add missing & > Receiving Used Buffers: prevent speculative load when not > sequentially consistent > > virtio-spec.lyx | 16 +++++++++++++--- > 1 files changed, 13 insertions(+), 3 deletions(-) Reviewed-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx> _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
