Re: Tracing NetBSD sun4v issues

[Palle Lyckegaard <palle%netbsd.org@localhost>]

On Fri, 9 Oct 2026, Sad Clouds wrote:

> I'm trying to trace the root cause of NetBSD issues on sun4v. I have a
> small user space test program that reliably dies with SIGSEGV. The test
> involves calling setpassent() which in turn calls nsdispatch() where it
> dies.

Would you be able to share the small user space program?

Is the problem a replacemet for the init(8) process or how is the program 
started?
Do you exit from sysinst(8) and run the program from the shell?

> 1) Why does GDB think the issues occurred in jemalloc? Does this
> indicate corruption of stack frames?
>
> 2) Assuming the stack frames are corrupt, does this mean that the
> disassembly of the instruction that caused SIGSEGV (restore) may also
> be suspicious and likely invalid?

I'm experiencing the same kind of user space crashes when running the 
normal sysinst(8) program.

Debugging the issue over the past year or so convinces me that the 
scenario happends from time to time when returning to user space from a system call.
The stack of the user process gets messed up somehow with incorrect values from the saved 
register windows (PCB).

Have you tried to run your small user program using qemu?
https://qemu.weilnetz.de/doc/6.0/system/target-sparc64.html

I replaced the Solaris S10image with the miniroot.fs from NetBSD and have 
used a gdb buildt for the sparc64 target to do single stepping in the 
NetBSD kernel.



Thanks for trying to help fixing some of the stability issues on sun4v :-)

Regards
Palle