> From: Michael S. Tsirkin <mst@xxxxxxxxxx> > Sent: Sunday, December 19, 2021 3:37 AM > > On Sat, Dec 18, 2021 at 01:53:01PM -0700, David Ahern wrote: > > On 12/17/21 1:08 AM, Parav Pandit wrote: > > > @@ -204,6 +217,8 @@ static void vdpa_opts_put(struct nlmsghdr *nlh, > struct vdpa *vdpa) > > > if (opts->present & VDPA_OPT_VDEV_MAC) > > > mnl_attr_put(nlh, VDPA_ATTR_DEV_NET_CFG_MACADDR, > > > sizeof(opts->mac), opts->mac); > > > + if (opts->present & VDPA_OPT_VDEV_MTU) > > > + mnl_attr_put_u16(nlh, VDPA_ATTR_DEV_NET_CFG_MTU, > opts->mtu); > > > > Why limit the MTU to a u16? Eric for example is working on "Big TCP" > > where IPv6 can work with Jumbograms where mtu can be > 64k. > > > > https://datatracker.ietf.org/doc/html/rfc2675 > > Well it's 16 bit at the virtio level, though we can extend that of course. Making > it match for now removes need for validation. > -- As Michael mentioned virtio specification limits the mtu to 64k-1. Hence 16-bit. First we need to update the virtio spec to support > 64K mtu. However, when/if (I don't know when) that happens, we need to make this also u32. So may be we can make it u32 now, but still restrict the mtu value to 64k-1 in kernel, until the spec is updated. Let me know, if you think that's future proofing is better, I first need to update the kernel to take nla u32. > MST _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
