port-sparc/60460: sparc fails to save/restore FPU registers on signal delivery

["campbell+netbsd%mumble.net@localhost via gnats" <gnats-admin%NetBSD.org@localhost>]

>Number:         60460
>Category:       port-sparc
>Synopsis:       sparc fails to save/restore FPU registers on signal delivery
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-sparc-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Jul 18 15:00:00 +0000 2026
>Originator:     Taylor R Campbell
>Release:        current, 11, 10, 9, 8, 7, 6, 5, 4, ...
>Organization:
The SparcFPU Foundation, Inc.
>Environment:
>Description:
https://releng.netbsd.org/b5reports/sparc/2026/2026.07.17.19.25.53/test.html#kernel_t_signal_and_fpu_double

Test case: kernel/t_signal_and_fpu/double

Duration: 0.090689 seconds
Termination reason

FAILED: /tmp/build/2026.07.17.19.25.53-sparc/src/tests/kernel/t_signal_and_fpu.c:150: test_result=0x43ff4
Test case: kernel/t_signal_and_fpu/float

Duration: 0.082650 seconds
Termination reason

FAILED: /tmp/build/2026.07.17.19.25.53-sparc/src/tests/kernel/t_signal_and_fpu.c:150: test_result=0x506ce
Test case: kernel/t_signal_and_fpu/ldouble

Duration: 0.078114 seconds
Termination reason

FAILED: /tmp/build/2026.07.17.19.25.53-sparc/src/tests/kernel/t_signal_and_fpu.c:150: test_result=0x3e357
>How-To-Repeat:
cd /usr/tests/kernel && atf-run t_signal_and_fpu | atf-report
>Fix:
Yes, please!

#define FPU_CONTEXT in sys/arch/sparc/sparc/machdep.c, perhaps?

Or just remove the #ifdef?