Subject: Re: Xarm32VIDC from 1.6.1 very unstable
To: Ben Harris <bjh21@netbsd.org>
From: Richard Earnshaw <rearnsha@buzzard.freeserve.co.uk>
List: port-acorn32
Date: 08/05/2003 22:36:07
> In article <20030805114913.X40343@mrhill.datenfreihafen.de> you write:
> >First, is still somebody actively maintaining the acorn32 port of NetBSD?
>
> When in breaks for me, I try to fix it. I occasionally look at PRs and try
> to fix them.
>
> >I installed the 1.6.1 release on a RiscPC/SA110/32 MB RAM and was very
> >impressed as it run out-of-the box, all hardware was detected and my
> >subjective impression of the performance is very good. Good work!
> >
> >However the X-server seems very unstable. As long as I use only the VIDC
> >console or only console via Xterm NetBSD runs stable like a rock. But
> >graphical interaction (resizing windows, opening windows, using a
> >webbrowser or a window manager) leads to a core dump of Xarm32VIDC sooner
> >or later.
>
> Hmm. Are you using a wscons-capable kernel? I use Xarm32VIDC on an NC on a
> daily basis, and it's really quite solid (until a run the machine out of
> swap, whereupon the X server tends to get killed and restarted).
>
> >- Is 1.6.1 and especially Xarm32VIDC ought to be stable?
>
> I can't actually speak for 1.6.1, since my NC runs 1.6A at the moment (the
> standard 1.6 wscons kernels missed out opms, which was fatal to X, and I
> haven't got around to looking at 1.6.1.
I found 1.6.1 to be unstable on my RISC PC -- There were some kernel
issues during the 1.6-1.6.1 transition that caused user-land instability,
that I thought I'd managed to back out before the release occurred. It
may turn out that there is still some other underlying problem.... ;-(
Having said that, -current isn't much better. Maybe it is a real bug in
the X server...
>
> >- Can netbsd cope with StrongARMs that suffer from the STM ^ bug?
>
> I believe so. As I understand it, this bug only bites when saving user-mode
> registers on entry to the kernel, and NetBSD's kernel entry sequence
> carefully avoids triggering the bug.
Processors suffering from that problem also suffer from a user-space ldm
bug that affects returning from a function call if the ldm is the last
instruction on a page. There's a package in the package system
(sysutils/fix4SA110rev2) that can be used to help to alleviate this, but
I'm not sure if it's been updated for ELF images.
>
> >- Is there an issue withloading coredumps into gdb? Whenever I tried this,
> > gdb says it does not understand the dump's fileformat.
>
> I'm sure I _have_ managed to load a coredump into gdb once, but I'm not sure
> it was anywhere near the 1.6 release.
>
If you are having problems, you might find a build of the standard GNU
release of GDB fixes your problems.
> >- I read about an in-kernel debugger ddb - how can it be activated?
>
> Build a kernel with "options DDB" (I think all the release kernels have it).
> The debugger will be entered on a panic, and you can drop into it using
> Ctrl+Alt+Esc (wscons kernels) or some other sequence I currently forget
> (non-wscons kernels).
>
You will have problems if you are trying to use the console for X and you
don't set up your system to have the "debug console" on a serial port,
since I don't believe the current WSCONS code on acorn32 supports
switching.
R.