How to debug BTX loader?

[Darmawan Salihun]

Hi John, 

--- On Thu, 12/2/10, 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: Thursday, December 2, 2010, 8:58 AM
> On Wednesday, December 01, 2010
> 4:09:42 pm Darmawan Salihun wrote:
> > Hi John, 
> > 
> > --- 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
> > > hand. 
> > > > However, the boot process always stuck in
> the BTX
> > > loader 
> > > > (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,
> > > etc.).
> > 
> > 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. 
> 
> Looks like the mailing list stripped the attachment. 
> Can you post the 
> attachment at a URL?
>

The BTX crash message is in the attachment.

Regards,

Darmawan