Re: Trouble booting RELENG 13.0 on a Zynq XC7Z010 (Zybo-like) board

On Fri, Jan 21, 2022 at 1:28 AM Milan Obuch <freebsd-arm@dino.sk> wrote:
>
> What about 'bt' output here? Knowing where the crash is occuring along
> with callstack should help abit...
>
> Regards,
> Milan
>

Typing bt at the KDB prompt does nothing useful.  Depending on how I
have the kernel options set, it either produces no stack trace or one
that is limited to a couple of functions inside the debugger.

I was tracing through with xsct this morning, with conflicting results
as to where the crash happens.  It's somewhere either in the call to
dbg_monitor_init() (from initarm()), or shortly after that call.
Sometimes I can get it to crash in dbg_reset_state(), but other times
it doesn't crash until later.  I think there is conflict between
running the xsct debugger and FreeBSD trying to configure the hardware
debug registers.  I think it is wiping out my xsct breakpoints in
hardware.

It still crashes even if I don't run it under the xsct debugger at all.

If I don't include "options DDB" in the kernel config file, and just
include KDB and KDB_TRACE, it doesn't crash until much later in the
boot process (due to a different issue).

For now I am pretty happy just excluding DDB from the config, but I'd
like to get it working eventually.

As for my earlier questions about boot code, I was looking through the
src/stand directory, and found a lot of useful info in there which I
am going to explore.

Thanks,

Lee