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Differential D42391

ethernet: Remove FCS bit
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Authored by zlei on Oct 28 2023, 8:39 PM.
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network
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rG09164454aa4c: ethernet: Retire M_HASFCS
Summary

The last consumer ng_atmllc has been removed in 105a4f7b3cb6 .

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zlei created this revision.Oct 28 2023, 8:39 PM
Herald added subscribers: glebius, melifaro, ae, imp. · View Herald TranscriptOct 28 2023, 8:39 PM
zlei requested review of this revision.Oct 28 2023, 8:39 PM
zlei retitled this revision from ethernet: Remove FCS check to ethernet: Remove FCS bit.
zlei added a comment.Oct 28 2023, 8:42 PM

This is a breaking change. 3rd party drivers should take care of it.

kp accepted this revision as: kp.Oct 30 2023, 11:19 AM
This revision is now accepted and ready to land.Oct 30 2023, 11:19 AM
emaste added a subscriber: emaste.May 11 2024, 12:21 AM

This is a breaking change. 3rd party drivers should take care of it.

It's fairly straightforward for 3rd party drivers to chase this tough, I don't think it's a big concern.

zlei added a comment.May 15 2024, 2:21 AM
In D42391#1030031, @emaste wrote:

This is a breaking change. 3rd party drivers should take care of it.

It's fairly straightforward for 3rd party drivers to chase this tough, I don't think it's a big concern.

I spent lots of time to check the 3rd party consumers ( mostly done by searching on github ) of M_HASFCS . There's only little consumers so I think it is time to commit this :)

zlei added a comment.May 15 2024, 2:28 AM

While Linux does support tap traffic without good CRC (FCS) via tcpdump / bpf. I think that is most useful for developing drivers / hardwares or diagnosing noisy wireless environment, but I think that (enable capturing bad CRC via bpf) should be turned on per interface and still those packets with bad CRC should not enter net stack. So I'm convinced this is the right approach.

adrian added a subscriber: adrian.May 15 2024, 2:41 AM

I'm sure I've seen FCSes in 802.11 bpf traces? Maybe that's happening at the 802.11 radiotap level?

zlei added a subscriber: bz.May 15 2024, 3:24 AM
In D42391#1031131, @adrian wrote:

I'm sure I've seen FCSes in 802.11 bpf traces? Maybe that's happening at the 802.11 radiotap level?

I'm not familiar with 802.11, But the manpage https://man.freebsd.org/cgi/man.cgi?query=ieee80211_radiotap says radiotap level would get FCS.

IEEE80211_RADIOTAP_F_FCS

Frame contents includes the FCS.

CC @bz , he is working on 802.11 .

Closed by commit rG09164454aa4c: ethernet: Retire M_HASFCS (authored by zlei). · Explain WhyJul 4 2024, 4:58 PM
This revision was automatically updated to reflect the committed changes.
zlei added a commit: rG09164454aa4c: ethernet: Retire M_HASFCS.

Revision Contents
Changeset List

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sys/
net/
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sys/net/debugnet.c

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sys/net/ethernet.h

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sys/net/if_ethersubr.c

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