Re: Abnormal behavior after bumping net.inet6.udp6.sendspace

[email protected] (Michael van Elst) Wed, 15 Jul 2026 20:18:11 -0000 (UTC)
Newsgroups gmane.os.netbsd.devel.network
Organization Serpens User Group
Message-ID <[email protected]>
[email protected] (Timo Buhrmester) writes:

>> It may be that sbmax should default to a larger value.
>Wouldn't it be relatively straightforward to guard against changing the
>send/recvspace sysctls past sbmax?

Yes. The socket buffer cannot be larger than sb_max_adj
where sb_max_adj = sb_max * MCLBYTES / (MSIZE + MCLBYTES).

MCLBYTES is 2048 for all archs
MSIZE is 256 or 256 depending on arch.

For amd64:   262144 * 2048 / (512 + 2048) = 209715


Of course you could then start sanitizing lots of other
sysctl values. I'm not sure if this is really worth it.