How to debug BTX loader?

[John Baldwin]

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?

-- 
John Baldwin