On Wed, 12 Aug 2026 10:35:25 +0000 Chia-Yu Chang (Nokia) wrote:
> > Tested on hns3 HW (2x 100G, direct cable, openEuler 24.03, kernel 
> > 7.2.0-rc6).
> > 
> > tcpdump confirms HW GRO zeroes IP ToS: aggregated (>MTU) packets carry tos 
> > 0x0, while non-aggregated packets keep their ToS/ECN marks — so the zeroing 
> > is done by HW GRO, not the sender. Before patch, CWR packets had 
> > SKB_GSO_TCP_ECN set (0x5 = SKB_GSO_TCPV4 | SKB_GSO_TCP_ECN). After patch, 
> > all GRO events gso_type=0x1 (SKB_GSO_TCPV4 only), no 0x5 observed.
> > 
> > Tested-by: Jijie Shao <[email protected]>  
> 
> Thanks Jijie for confirmation, I will submit to net in the next round.

Hold on.. Sounds like hns3 zeros ToS out (?!)

This would be invalid and illegal for HW-GRO. If hns3 nukes crucial IP
header fields it should probably be advertising LRO not HW-GRO in the
first place.

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