* why does virtio not support IPv4 CKSUM?
@ 2023-07-06 3:47 jiangheng (G)
2023-07-06 14:37 ` Stephen Hemminger
0 siblings, 1 reply; 4+ messages in thread
From: jiangheng (G) @ 2023-07-06 3:47 UTC (permalink / raw)
To: maxime.coquelin, chenbo.xia; +Cc: users
Hi
why does virtio not support IPv4 CKSUM? But support TCP/UDP cksum.
If not support ipv4 cksum, when I use GRO, the ip cksum of the packets transmitted to ip layer will be incorrect.
I have to calculate ip cksum before packet was transmiited to ip layer.
So why does virtio not support ipv4 cksum ?
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: why does virtio not support IPv4 CKSUM?
2023-07-06 3:47 why does virtio not support IPv4 CKSUM? jiangheng (G)
@ 2023-07-06 14:37 ` Stephen Hemminger
2023-07-07 12:21 ` 答复: " jiangheng (G)
0 siblings, 1 reply; 4+ messages in thread
From: Stephen Hemminger @ 2023-07-06 14:37 UTC (permalink / raw)
To: jiangheng (G); +Cc: maxime.coquelin, chenbo.xia, users
On Thu, 6 Jul 2023 03:47:26 +0000
"jiangheng (G)" <jiangheng14@huawei.com> wrote:
> Hi
>
> why does virtio not support IPv4 CKSUM? But support TCP/UDP cksum.
Because virtio is a software driver developed on Linux and Linux doesn't need/want IP checksum offload.
It takes longer to look at offload bits then to compute checksum in SW.
>
> If not support ipv4 cksum, when I use GRO, the ip cksum of the packets transmitted to ip layer will be incorrect.
> I have to calculate ip cksum before packet was transmiited to ip layer.
> So why does virtio not support ipv4 cksum ?
^ permalink raw reply [flat|nested] 4+ messages in thread
* 答复: why does virtio not support IPv4 CKSUM?
2023-07-06 14:37 ` Stephen Hemminger
@ 2023-07-07 12:21 ` jiangheng (G)
2023-07-07 12:34 ` jiangheng (G)
0 siblings, 1 reply; 4+ messages in thread
From: jiangheng (G) @ 2023-07-07 12:21 UTC (permalink / raw)
To: Stephen Hemminger; +Cc: maxime.coquelin, chenbo.xia, users
>> Hi
>>
>> why does virtio not support IPv4 CKSUM? But support TCP/UDP cksum.
> Because virtio is a software driver developed on Linux and Linux doesn't need/want IP checksum offload.
> It takes longer to look at offload bits then to compute checksum in SW.
However, Virtio supports LRO. Is it possible to merge packets with incorrect cksum?
>>
>> If not support ipv4 cksum, when I use GRO, the ip cksum of the packets transmitted to ip layer will be incorrect.
>> I have to calculate ip cksum before packet was transmiited to ip layer.
>> So why does virtio not support ipv4 cksum ?
^ permalink raw reply [flat|nested] 4+ messages in thread
* why does virtio not support IPv4 CKSUM?
2023-07-07 12:21 ` 答复: " jiangheng (G)
@ 2023-07-07 12:34 ` jiangheng (G)
0 siblings, 0 replies; 4+ messages in thread
From: jiangheng (G) @ 2023-07-07 12:34 UTC (permalink / raw)
To: Stephen Hemminger; +Cc: maxime.coquelin, chenbo.xia, users
>> Hi
>>
>> why does virtio not support IPv4 CKSUM? But support TCP/UDP cksum.
> Because virtio is a software driver developed on Linux and Linux doesn't need/want IP checksum offload.
> It takes longer to look at offload bits then to compute checksum in SW.
However, Virtio supports LRO. Is it possible to merge packets with incorrect cksum?
Must cksum offload be enabled when LRO enabled?
>>
>> If not support ipv4 cksum, when I use GRO, the ip cksum of the packets transmitted to ip layer will be incorrect.
>> I have to calculate ip cksum before packet was transmiited to ip layer.
>> So why does virtio not support ipv4 cksum ?
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2023-07-07 12:34 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2023-07-06 3:47 why does virtio not support IPv4 CKSUM? jiangheng (G)
2023-07-06 14:37 ` Stephen Hemminger
2023-07-07 12:21 ` 答复: " jiangheng (G)
2023-07-07 12:34 ` jiangheng (G)
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