dmesg giving wrong output regarding MPTCP

[somnathjena2011]

I was configuring a new linux kernel 5.6.9 from my Ubuntu 20.04 linux kernel 5.11.0-27-generic.
On doing dmesg | grep MPTCP in 5.11.0-27-generic, following was the output:
[ 1.084739] MPTCP token hash table entries: 4096 (order: 4, 98304 bytes, linear)

On doing dmesg | grep MPTCP in 5.6.9, following the output was NULL

Here are the configurations regarding MPTCP in 5.11.0-27-generic:

CONFIG_MPTCP=y
CONFIG_INET_MPTCP_DIAG=m
CONFIG_MPTCP_IPV6=y

Here are the configurations regarding MPTCP in 5.6.9:

CONFIG_MPTCP=y
CONFIG_MPTCP_IPV6=y
## CONFIG_MPTCP_HMAC_TEST is not set

My question is since MPTCP is included in the configuration and also for IPv6, why is dmesg not showing the version number?

[matttbe]

Hello,

First, be careful that there are two major MPTCP implementation in the Linux kernel: https://github.com/multipath-tcp/mptcp_net-next/wiki#upstream-vs-out-of-tree-implementations

Here you are using the upstream implementation and reporting an issue on the 'out-of-tree' project.
I'm going to move this to the other project.

[matttbe]

My question is since MPTCP is included in the configuration and also for IPv6, why is dmesg not showing the version number?

I'm not sure to understand your question.

MPTCP in the upstream kernel is still under development: https://github.com/multipath-tcp/mptcp_net-next/wiki#changelog
Some features have been added later like the token hash table.
If you don't see it in your v5.6 kernel, it doesn't mean MPTCP is not available. There are other ways to check MPTCP is available: https://developers.redhat.com/blog/2020/08/19/multipath-tcp-on-red-hat-enterprise-linux-8-3-from-0-to-1-subflows/

Can we close the ticket?

[somnathjena2011]

Thanks very much for the clarification. I checked using the sysctl command and think MPTCP is enabled. You can close it now.

…

On Tue, 24 Aug 2021 at 22:13, Matthieu Baerts ***@***.***> wrote: My question is since MPTCP is included in the configuration and also for IPv6, why is dmesg not showing the version number? I'm not sure to understand your question. MPTCP in the upstream kernel is still under development: https://github.com/multipath-tcp/mptcp_net-next/wiki#changelog Some features have been added later like the token hash table. If you don't see it in your v5.6 kernel, it doesn't mean MPTCP is not available. There are other ways to check MPTCP is available: https://developers.redhat.com/blog/2020/08/19/multipath-tcp-on-red-hat-enterprise-linux-8-3-from-0-to-1-subflows/ Can we close the ticket? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#228 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AMBMEW2AOWKDLW7QHANM7QTT6PD4RANCNFSM5CXHIMUQ> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&utm_campaign=notification-email> .

[matttbe]

👍

One last thing before closing this ticket: MPTCP on a v5.6 has very limited features. It was enough to start getting some apps ready but not sure there is an interest to use MPTCP with only one subflow :)
https://github.com/multipath-tcp/mptcp_net-next/wiki#changelog