OK sure will do that.
-----Original Message-----
From: Yuanhan Liu [mailto:yuanhan....@linux.intel.com]
Sent: Tuesday, September 27, 2016 7:12 PM
To: Dey, Souvik <sodey at sonusnet.com>
Cc: Stephen Hemminger <stephen at networkplumber.org>; Kavanagh, Mark B
<mark.b.kavanagh at intel.com>; dev at dpdk.org
Subject: Re: [PATCH v6] net/virtio: add set_mtu in virtio
On Tue, Sep 27, 2016 at 08:44:20PM +0000, Dey, Souvik wrote:
> Hi Stephen,
> So what should be my next steps , should I submit a v7 for this patch
> or you suggest otherwise.
Yes, please. Another note is please don't use white space for indentation, use
TAB instead.
-yliu
>
> --
> Regards,
> Souvik
>
> -----Original Message-----
> From: Stephen Hemminger [mailto:stephen at networkplumber.org]
> Sent: Tuesday, September 27, 2016 2:57 PM
> To: Dey, Souvik <sodey at sonusnet.com>
> Cc: Kavanagh, Mark B <mark.b.kavanagh at intel.com>; Yuanhan Liu
> <yuanhan.liu at linux.intel.com>; dev at dpdk.org
> Subject: Re: [PATCH v6] net/virtio: add set_mtu in virtio
>
> On Fri, 23 Sep 2016 15:17:37 +0000
> "Dey, Souvik" <sodey at sonusnet.com> wrote:
>
> > Hi Liu/Mark/Stephen,
> >
> > I have tried to modify the code with all of your latest
> > comments. Do let me know if this looks fine or you have more comments.
> >
> >
> >
> > Changes done :
> >
> > -- max frame ize is compare to VIRTIO_MAX_RX_PKTLEN instead of
> > dev_info.max_rx_pktlen
> >
> > -- removed the CRC_LEN from the ether_len calculation and added the
> > merge rx buf hdr len. ether_hdr_len = ETHER_HDR_LEN + VLAN_TAG_SIZE
> > +
> > hw->vtnet_hdr_size
> >
> > -- Still retained the VLAN Size as the worst case scenario.
> >
> >
> >
> >
> >
> > --
> >
> > drivers/net/virtio/virtio_ethdev.c | 16 ++++++++++++++++
> >
> > 1 file changed, 16 insertions(+)
> >
> >
> >
> > diff --git a/drivers/net/virtio/virtio_ethdev.c
> > b/drivers/net/virtio/virtio_ethdev.c
> >
> > index 423c597..1dbfea6 100644
> >
> > --- a/drivers/net/virtio/virtio_ethdev.c
> >
> > +++ b/drivers/net/virtio/virtio_ethdev.c
> >
> > @@ -653,12 +653,20 @@ virtio_dev_allmulticast_disable(struct
> > rte_eth_dev *dev)
> >
> > PMD_INIT_LOG(ERR, "Failed to disable allmulticast");
> >
> > }
> >
> >
> >
> > +#define VLAN_TAG_SIZE 4 /* 802.3ac tag (not DMA'd) */
> >
> > +
> >
> > +static int virtio_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
> >
> > +{
> >
> > + struct virtio_hw *hw = dev->data->dev_private;
> >
> > + uint32_t ether_hdr_len = ETHER_HDR_LEN + VLAN_TAG_SIZE
> > + +
> > + hw->vtnet_hdr_size;
> >
> > + uint32_t frame_size = mtu + ether_hdr_len;
> >
> > +
> >
> > + if (mtu < ETHER_MIN_MTU || frame_size >
> > + VIRTIO_MAX_RX_PKTLEN ) {
> >
> > + PMD_INIT_LOG(ERR, "MTU should be between
> > + %d and %d\n",
> >
> > + ETHER_MIN_MTU,
> > + VIRTIO_MAX_RX_PKTLEN);
> >
> > + return -EINVAL;
> >
> > + }
> >
> > + return 0;
> >
> > +}
> >
> >
> >
> > /*
> >
> > * dev_ops for virtio, bare necessities for basic operation
> >
> > */
> >
> > @@ -677,7 +685,6 @@ static const struct eth_dev_ops
> > virtio_eth_dev_ops = {
> >
> > .allmulticast_enable = virtio_dev_allmulticast_enable,
> >
> > .allmulticast_disable = virtio_dev_allmulticast_disable,
> >
> > + .mtu_set = virtio_mtu_set,
> >
> > .dev_infos_get = virtio_dev_info_get,
> >
> > .stats_get = virtio_dev_stats_get,
> >
> > .xstats_get = virtio_dev_xstats_get,
> >
> > --
> >
> > Please do let me know if this looks good to you all. Thanks
> >
> >
> >
> > --
> >
> > Regards,
> >
> > Souvik
> >
> >
> >
> > -----Original Message-----
> > From: Kavanagh, Mark B [mailto:mark.b.kavanagh at intel.com]
> > Sent: Friday, September 23, 2016 5:08 AM
> > To: Yuanhan Liu <yuanhan.liu at linux.intel.com>; Stephen Hemminger
> > <stephen at networkplumber.org>
> > Cc: Dey, Souvik <sodey at sonusnet.com>; dev at dpdk.org
> > Subject: RE: [PATCH v6] net/virtio: add set_mtu in virtio
> >
> >
> >
> > >Subject: Re: [PATCH v6] net/virtio: add set_mtu in virtio
> >
> > >
> >
> > >On Wed, Sep 21, 2016 at 06:45:05PM -0700, Stephen Hemminger wrote:
> >
> > >> On Thu, 22 Sep 2016 00:08:38 +0000
> >
> > >> "Dey, Souvik" <sodey at sonusnet.com<mailto:sodey at sonusnet.com>>
> > >> wrote:
> >
> > >>
> >
> > >> > Answers inline.
> >
> > >> >
> >
> > >> > --
> >
> > >> > Regards,
> >
> > >> > Souvik
> >
> > >> >
> >
> > >> > -----Original Message-----
> >
> > >> > From: Stephen Hemminger [mailto:stephen at networkplumber.org]
> >
> > >> > Sent: Wednesday, September 21, 2016 7:22 PM
> >
> > >> > To: Dey, Souvik <sodey at sonusnet.com<mailto:sodey at sonusnet.com>>
> >
> > >> > Cc:
> > >> > mark.b.kavanagh at intel.com<mailto:mark.b.kavanagh at intel.com>;
> > >> > yuanhan.liu at linux.intel.com<mailto:yuanhan.liu at linux.intel.com>
> > >> > ;
> >
> > >> > dev at dpdk.org<mailto:dev at dpdk.org>
> >
> > >> > Subject: Re: [PATCH v6] net/virtio: add set_mtu in virtio
> >
> > >> >
> >
> > >> > On Wed, 21 Sep 2016 19:11:47 -0400
> >
> > >> > Dey <sodey at sonusnet.com<mailto:sodey at sonusnet.com>> wrote:
> >
> > >> >
> >
> > >> > >
> >
> > >> > > +
> >
> > >> > > +#define VLAN_TAG_SIZE 4 /* 802.3ac tag (not DMA'd) */
> >
> > >> > > +
> >
> > >> > > +static int virtio_mtu_set(struct rte_eth_dev *dev, uint16_t
> > >> > > +mtu) {
> >
> > >> > > + struct rte_eth_dev_info dev_info;
> >
> > >> > > + uint32_t ether_hdr_len = ETHER_HDR_LEN +
> > >> > > + ETHER_CRC_LEN
> > >> > > + + VLAN_TAG_SIZE;
> >
> > >> > > + uint32_t frame_size = mtu + ether_hdr_len;
> >
> > >> > > +
> >
> > >> > > + virtio_dev_info_get(dev, &dev_info);
> >
> > >> > > +
> >
> > >> > > + if (mtu < ETHER_MIN_MTU || frame_size >
> > >> > > + dev_info.max_rx_pktlen) {
> >
> > >> > > + PMD_INIT_LOG(ERR, "MTU should be between %d
> > >> > > + and %d\n",
> >
> > >> > > + ETHER_MIN_MTU,
> >
> > >> > > + (dev_info.max_rx_pktlen -
> > >> > > + ether_hdr_len));
> >
> > >> > > + return -EINVAL;
> >
> > >> > > + }
> >
> > >> > > + return 0;
> >
> > >> > > +}
> >
> > >> >
> >
> > >> > I am fine with the general idea of this patch but:
> >
> > >> > 1. Calling virtio_dev_info_get is needlessly wasteful when
> > >> > all you want
> >
> > >> > is to access the max packet length. Since max_rx_pktlen is
> > >> > always
> >
> > >> > VIRTIO_MAX_RX_PKTLEN, please just use that.
> >
> > >> > [Dey, Souvik] I am using the virtio_dev_info_get as in future
> >
> > >> > can/may support the
> >
> > >max_rx_pktlen as a variable to be set by the application. This
> > >will
> >
> > >keep the changes future proof. As we need to support till 65535 instead of
> > >9728 as the linux does.
> >
> > >>
> >
> > >> Fine, then just dereference hw->rx_max_pktlen. Driver code
> > >> can/should
> >
> > >> reference its own data directly.
> >
> > >
> >
> > >Dey, maybe you could just use VIRTIO_MAX_RX_PKTLEN here, like what
> > >you
> >
> > >did in early versions.
> >
> > >
> >
> > >> >
> >
> > >> > 2. Defining VLAN_TAG_SIZE is irrelevant if doing vlan offload.
> >
> > >> > [Dey, Souvik] vlan offload is not mandatory. Se again still
> > >> > have
> >
> > >> > vlan being sent up to
> >
> > >the application. In that case we need to consider the vlan length in the
> > >Ethernet size.
> >
> > >>
> >
> > >> The code needs to handle both vlan offload (or not), correctly.
> > >> You
> >
> > >> are assuming the worst case here.
> >
> > >
> >
> > >I think we are fine here to assume worst case.
> >
> > >
> >
> > >> >
> >
> > >> > 3. Virtio doesn't insert CRC, therefore CRC_LEN is irrelevant
> >
> > >> > [Dey, Souvik] I am not sure of this. Mark commented earlier to
> > >> > consider this length too.
> >
> > >Mark what do you suggest ?
> >
> > >>
> >
> > >> Actually, the thing that matters is the size of the merge rx buf header,
> > >> not the CRC.
> >
>
> This patch is good enough for now, but not fully correct.
> The actual max value depends on the host negotiation protocol, ie merge rx
> buf is only sometimes used.
>
> There was some discussion on netdev mailing list to pass MTU from host to
> guest in virtio, not sure where that landed.
