Re: NetBSD 11/Xen does not like many CPUs

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Sat, Oct 03, 2026 at 12:17:37AM +0300, Staffan Thomen wrote:
> Hey list,
> 
> I've been upgrading my Xen hosts to NetBSD 11 and the XEN3_DOM0 kernel
> seems to not like systems with many cores (one system has 24 and the
> other has 80 cores) and both panic with some flavor of:
> 
> [   1.0000030] panic: pirq 4991 out of bound, increase NR_PIRQS
> 
> ...if I don't limit the number of cores on the DOM0 using the
> dom0_max_vcpus flag to the xen kernel. I wouldn't have noticed since I
> previously used to limit and pin the vcpus but I seem to recall reading
> that limiting and pinning vcpus for the DOM0 is no longer recommended
> with a recent Xen kernel.
> 
> GENERIC does not have this issue and works with all cores.
> 
> It's not a super big deal, but I wanted to make it known I bumped into a
> panic.

Yes it's a known issue

> 
> Additionally I noticed that with netbsd-11 I can no longer use
> TOOLDIR=.../tools-${MACHINE} as configure injects MACHINE=xen before the
> template in the kernel Makefile making it expand to .../tools-xen. It
> seems wrong to me that MACHINE would be set by anything in the build.

Actually it's OK, see "OPTIONS SELECTION" in config(5)

Maybe you want to use ${ARCH} instead of ${MACHINE} ?

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--