kern/60220: kernel panic after modifying floating-point status register

["bruno%clisp.org@localhost via gnats" <gnats-admin%NetBSD.org@localhost>]

>Number:         60220
>Category:       kern
>Synopsis:       kernel panic after modifying floating-point status register
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Apr 30 21:50:00 +0000 2026
>Originator:     Bruno Haible
>Release:        11.0_RC3
>Organization:
GNU
>Environment:
NetBSD netbsd11.bruno.haible.de 11.0_RC3 NetBSD 11.0_RC3 (GENERIC) #0: Sat Apr  4 06:08:56 UTC 2026  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64

>Description:
During execution of a program that manipulates the floating-point status register (mxcsr), a kernel panic occurs. Most often with the message "panic: cpu0: softints stuck for 16 seconds"

>How-To-Repeat:
As root do:

pkg_add git autoconf automake python314
ln -s python3.14 /usr/pkg/bin/python3

As a normal user do:

git clone --depth 1 https://git.savannah.gnu.org/git/gnulib.git
cd gnulib
./gnulib-tool --create-testdir --dir=testdir fenv-exceptions-trapping
cd testdir
./configure
make
sync
make check

It is during the "make check" command, during execution of test-fenv-except-trapping-2.sh, that the kernel panic occurs.

>Fix: