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From: "jiangheng (G)" <jiangheng14@huawei.com>
To: Stephen Hemminger <stephen@networkplumber.org>
CC: "maxime.coquelin@redhat.com" <maxime.coquelin@redhat.com>,
 "chenbo.xia@intel.com" <chenbo.xia@intel.com>, "users@dpdk.org"
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Subject: why does virtio not support IPv4 CKSUM?
Thread-Topic: why does virtio not support IPv4 CKSUM?
Thread-Index: AdmvuxqAKvq8Er9ET6qfcLzNpsfxSgAGT/6AAD48ScAAAHmfUA==
Date: Fri, 7 Jul 2023 12:34:32 +0000
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>> Hi=20
>>=20
>> 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 incorrec=
t cksum?
Must cksum offload be enabled when LRO enabled?

>>=20
>> If not support ipv4 cksum, when I use GRO, the ip cksum of the packets t=
ransmitted 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 ?