Hi ,
Currently as you have mentioned, I have changed the code to:
static int
virtio_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
{
struct virtio_hw *hw = dev->data->dev_private;
- if (unlikely(mtu < (uint32_t)hw->vtnet_hdr_size + ETHER_HDR_LEN)) {
- return -1;
+ if (unlikely(mtu < VIRTIO_MIN_RX_BUFSIZE || mtu > VIRTIO_MAX_RX_PKTLEN)) {
+ PMD_INIT_LOG(ERR,"Mtu should be between 64 and 9728."
+ return -EINVAL;
}
return 0;
}
Yes, we should support till 64K as the kernel does , but I need to go through
the changes and test it properly before submitting it for review. Moreover I
was thinking with the changes in the mtu, we should also support multi-segment
buffers in kni. What do you suggest ?
--
Regards,
Souvik
-----Original Message-----
From: Stephen Hemminger [mailto:step...@networkplumber.org]
Sent: Saturday, August 27, 2016 8:16 PM
To: Dey, Souvik <sodey at sonusnet.com>
Cc: huawei.xie at intel.com; yuanhan.liu at linux.intel.com; dev at dpdk.org
Subject: Re: [dpdk-dev] [PATCH v1] add mtu set in virtio
On Fri, 26 Aug 2016 20:54:28 -0400
souvikdey33 <sodey at sonusnet.com> wrote:
> This functionality is required mostly in the cloud infrastructure.
> For example, if we use gre or vxlan network between compute and
> controller, then we should not use 1500 mtu in the guest as with
> encapsulation the sixe of the packet will be more and will get dropped
> in the infrastructure. So, in that case we should honor the mtu size
> sent by the dhcp server and configure the same on the virtual
> interfaces in the guest. This will also keep a consistent mtu through
> out the infrastructure.
>
> souvikdey33 (1):
> Signed-off-by: Souvik Dey <sodey at sonusnet.com>
>
> drivers/net/virtio/virtio_ethdev.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
Thanks for the patch, it is a good step forward but it looks like more code is
needed to do this safely. At a minimum, need to check that MTU is not greater
than VIRTIO_MAX_RX_PKTLEN.
And error return should be negative errno not -1.
Something like:
if (mtu < VIRTIO_MIN_MTU || mtu > VIRTIO_MAX_RX_PKTLEN)
return -EINVAL;
Looking at Linux driver, it allows MTU of up to 64K, yet DPDK only allows 9728.
That should probably be fixed.
