Warning on Linux kernel < 2.6.31 (Re: SoftIoc with Warning: Unable to clear IP_MULTICAST_ALL on Ubunto on WSL)

[Shuei YAMADA via Tech-talk <tech-talk at aps.anl.gov>]

Dear colleagues,

I'm testing EPICS R7.0.8.1 on an embedded linux system (Yokogawa
F3RP61),  whose linux kernel is 2.6.26. When I start IOC on it I get
following message:

Warning: Unable to clear IP_MULTICAST_ALL (err=92). This may cause
problems on multi-homed hosts

The same applies when I run caget or camonitor on F3RP61.

I found that EPICS Base #defines IP_MULTICAST_ALL if the kernel header
does not #defines it.

This results to calling setsockopt() with IP_MULTICAST_ALL on those
old linux kernels which do not support this option, which definitely
fails and results in the warning.

Is there no way to avoid this warning other than upgrading kernel>=
2.6.31? - which means replacing 15-Years-old F3RP61 with something
else. It is unlikely that Yokogawa provides an up-to-date kernel for
such an old product.

# Of course I can patch the EPICS base installed on our site, but ...

regards,
Shuei

> Hello,
>
>
> I'm testing the current softIoc (EPICS R7.0.7.1-DEV Rev. R7.0.7-194-g7a65c001ce178f2547fa) on a Windows subsystem for Linux (WSL). The subsystem is Ubuntu 22.04.3.
> When I start the softIoc I always get the following message:
>
> Warning: Unable to clear IP_MULTICAST_ALL (err=92). This may cause problems on multi-homed hosts
>
> Apart from this warning, everything seems to work fine.
>
> Is this a WSl thing or a misconfiguration? How can I fix this?
>
> Best,
> Carsten

--
                 ----------------------------------------------------
                 Shuei Yamada,
                 High Energy Accelerator Research Organization (KEK)
                 mailto:shuei at post.kek.jp
                 ----------------------------------------------------