[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH net-next v2 1/5] xen-netback: add IPv6 checksum offload to guest
> -----Original Message----- > From: Wei Liu [mailto:wei.liu2@xxxxxxxxxx] > Sent: 08 October 2013 14:10 > To: Paul Durrant > Cc: xen-devel@xxxxxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; Wei Liu; David Vrabel; > Ian Campbell > Subject: Re: [PATCH net-next v2 1/5] xen-netback: add IPv6 checksum > offload to guest > > On Tue, Oct 08, 2013 at 11:58:12AM +0100, Paul Durrant wrote: > > Check xenstore flag feature-ipv6-csum-offload to determine if a > > guest is happy to accept IPv6 packets with only partial checksum. > > Also check analogous feature-ip-csum-offload to determone if a > > determone -> determine > Ok. > > guest is happy to accept IPv4 packets with only partial checksum > > as a replacement for a negated feature-no-csum-offload value and > > add a comment to deprecate use of feature-no-csum-offload. > > > [...] > > @@ -306,7 +308,7 @@ struct xenvif *xenvif_alloc(struct device *parent, > domid_t domid, > > vif->domid = domid; > > vif->handle = handle; > > vif->can_sg = 1; > > - vif->csum = 1; > > + vif->ip_csum = 1; > > Not setting a default value for vif->ipv6_csum? > The default is 0 so no need. > > vif->dev = dev; > > > [...] > > + /* Before feature-ipv6-csum-offload was introduced, checksum > offload > > + * was turned on by a zero value in (or lack of) > > + * feature-no-csum-offload. Therefore, for compatibility, assume > > + * that if feature-ip-csum-offload is missing that IP (v4) offload > > + * is turned on. If this is not the case then the flag will be > > + * cleared when we subsequently sample feature-no-csum-offload. > > + */ > > + if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-ip-csum- > offload", > > + "%d", &val) < 0) > > + val = 1; > > + vif->ip_csum = !!val; > > + > > + if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-ipv6-csum- > offload", > > + "%d", &val) < 0) > > + val = 0; > > + vif->ipv6_csum = !!val; > > + > > + /* This is deprecated. Frontends should set IP v4 and v6 checksum > > + * offload using feature-ip-csum-offload and > > + * feature-ipv6-csum-offload respectively. > > + */ > > These comments on feature flags should also be synchronized to master > netif.h in Xen and Linux's header. We've been trying to document thing > along the way for quite some time and the long term benifit is big. > Ok. That sounds like a good idea. I'll add a patch to do that. > > if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum- > offload", > > "%d", &val) < 0) > > val = 0; > > - vif->csum = !val; > > + if (val) > > + vif->ip_csum = 0; > > Do you also need to set vif->ipv6_csum to 0? I don't think a frontend > which cannot deal with V4 csum offload has the ability to deal with V6 > csum offload. > I was just trying to preserve the existing semantic of feature-no-csum-offload, which only affects v4. Since it's deprecated, should we add a new semantic? Paul _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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