Bug#1063753: systemd: IFB network devices are no longer autocreated when ifb module is loaded

[Luca Boccassi]

Control: tags -1 wontfix
Control: close -1

On Mon, 12 Feb 2024 08:33:21 +0100 Andreas Sundstrom
<sunkan+debian.bugs at zappa.cx> wrote:
> Package: systemd
> Version: 252.22-1~deb12u1
> Severity: important
> X-Debbugs-Cc: sunkan+debian.bugs at zappa.cx
> 
> Dear Maintainer,
> 
> After upgrading systemd from 252.19-1~deb12u1 to 252.22-1~deb12u1
> (Bookworm 12.4 to 12.5) the IFB network devices are no longer
> automatically created when loading the `ifb` module. This is a
> regression since previous releases as there is nothing mentioned
about
> this in the changelog.
> 
> It seems the root cause is that the following has been added to
> /lib/modprobe.d/systemd.conf
> 
> [part of .../systemd.conf]
> # Do the same for ifb0.
> 
> options ifb numifbs=0
> [end]
> 
> How this will affect your system depends a lot on what you use the
IFB
> device(s) for. In my case it is used in combination with a QoS
> scheduling/shaping setup.
> 
> For now I have worked around this change by adding the IFB device I
> needed manually with the command `ip link add ifb0 numtxqueues 8 type
> ifb`. And from what I can tell the kernel default setting is
> `numifbs=2`.

This is the intended default as suggested by the kernel maintainers.
Just add a drop-in in /etc/modprobe.d/ if the default doesn't work for
you.

-- 
Kind regards,
Luca Boccassi
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