How to debug BTX loader?
darmawan_salihun at yahoo.com
Wed Dec 1 21:09:45 UTC 2010
--- On Tue, 11/30/10, John Baldwin <jhb at freebsd.org> wrote:
> From: John Baldwin <jhb at freebsd.org>
> Subject: Re: How to debug BTX loader?
> To: freebsd-hackers at freebsd.org
> Cc: "Darmawan Salihun" <darmawan_salihun at yahoo.com>
> Date: Tuesday, November 30, 2010, 9:38 AM
> On Monday, November 29, 2010 1:01:27
> pm Darmawan Salihun wrote:
> > Hi guys,
> > I'm currently working on a BIOS for a custom Single
> Board Computer (SBC).
> > I have the required BIOS source code and tools at
> > However, the boot process always stuck in the BTX
> > (the infamous "ACPI autoload failed") when I booted
> out of USB stick
> > (with the FreeBSD 8.1 USB stick image).
> > I could get the system to boot into FreeBSD 8.1
> > (by keeping the CDROM tray open and close it when the
> board looks for
> > boot device, otherwise BTX will reboot instantly).
> Are you getting an actual BTX error message or a
> freeze? BTX is just a
> minikernel written all in assembly. It doesn't handle
> loading the kernel,
> etc. All that work is done by the /boot/loader
> program (which is written in
> C). You can find all the source to the boot code in
> src/sys/boot. The BTX
> kernel is in src/sys/boot/i386/btx/btx/.
> However, to debug this further we would need more info such
> as what exactly
> you are seeing (a hang, a BTX fault with a register dump,
One of the BTX fault shows the register dump in the attachment.
I hope this could help. Anyway, If I were to try to interpret
such register dump, where should I start? I understand x86/x86_64
assembly pretty much, but I'm not quite well versed with the
FreeBSD code using it.
> John Baldwin
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