Plan9port rebuild required after OpenBSD 7.5 -> 7.6 upgrade

[sqweek]

Hi folks,

I finally updated my OpenBSD server to 7.6 and discovered that all p9p binaries were immediately dying with a similar error:

$ 9 rc

rc[86673]: pinsyscalls addr 8818af6d858 code 253, pinoff 0xffffffff (pin 330 88206e34000-88206e42663 e663) (libcpin 0 0-0 0) error 78
Abort trap

$ 9 mk

mk[99224]: pinsyscalls addr 86b0ad6b858 code 253, pinoff 0xffffffff (pin 330 86b68c67000-86b68c75663 e663) (libcpin 0 0-0 0) error 78
Abort trap

$ 9 acme

acme[35073]: pinsyscalls addr e233c706858 code 253, pinoff 0xffffffff (pin 330 e22d7a66000-e22d7a74663 e663) (libcpin 0 0-0 0) error 78
Abort trap

I recompiled p9p from the latest master and this has resolved the issue. My previous p9p install was built on 2018-03-27 so I'm unsure if the old binaries are simply coupled to the earlier kernel version somehow, or if there was a source change that fixed this.

The 7.6 release announcement <https://www.openbsd.org/76.html> includes this change:

Deleted the msyscall mechanism, now replaced by the stricter mimmutable(2) and pinsyscalls(2).

Which I think leans towards the first hypothesis as I don't see plan9port calling any of msyscall/mimmutable/pinsyscalls. Older non-p9p binaries that I've compiled on this host (eg. python3.11 and go 1.23) are running fine.

Anyway everything is working after the rebuild so I don't really care enough to investigate further, but I've never seen this with previous OpenBSD upgrades and a web search revealed no similar issues so I thought I would leave some documentation behind :)

-sqweek

[Dan Cross]

This is an OpenBSD thing, though more of a combination of a
libc+kernel thing than just the kernel itself.

I believe the provide a binary package for plan9ports; I'd install
that and let them deal with it, rather than compiling it myself?

- Dan C.