Date: Thu, 2 Dec 2010 05:09:42 +0800 (SGT) From: Darmawan Salihun <darmawan_salihun@yahoo.com> To: freebsd-hackers@freebsd.org Subject: Re: How to debug BTX loader? Message-ID: <948728.57388.qm@web76807.mail.sg1.yahoo.com>
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Hi John, =0A=0A--- On Tue, 11/30/10, John Baldwin <jhb@freebsd.org> wrote:=
=0A=0A> From: John Baldwin <jhb@freebsd.org>=0A> Subject: Re: How to debug =
BTX loader?=0A> To: freebsd-hackers@freebsd.org=0A> Cc: "Darmawan Salihun" =
<darmawan_salihun@yahoo.com>=0A> Date: Tuesday, November 30, 2010, 9:38 AM=
=0A> On Monday, November 29, 2010 1:01:27=0A> pm Darmawan Salihun wrote:=0A=
> > Hi guys, =0A> > =0A> > I'm currently working on a BIOS for a custom Sin=
gle=0A> Board Computer (SBC). =0A> > I have the required BIOS source code a=
nd tools at=0A> hand. =0A> > However, the boot process always stuck in the =
BTX=0A> loader =0A> > (the infamous "ACPI autoload failed") when I booted=
=0A> out of USB stick =0A> > (with the FreeBSD 8.1 USB stick image). =0A> >=
=0A> > I could get the system to boot into FreeBSD 8.1 =0A> > (by keeping =
the CDROM tray open and close it when the=0A> board looks for =0A> > boot d=
evice, otherwise BTX will reboot instantly). =0A> =0A> Are you getting an a=
ctual BTX error message or a=0A> freeze?=A0 BTX is just a =0A> minikernel w=
ritten all in assembly.=A0 It doesn't handle=0A> loading the kernel, =0A> e=
tc.=A0 All that work is done by the /boot/loader=0A> program (which is writ=
ten in =0A> C).=A0 You can find all the source to the boot code in=0A> src/=
sys/boot.=A0 The BTX =0A> kernel is in src/sys/boot/i386/btx/btx/.=0A> =0A>=
However, to debug this further we would need more info such=0A> as what ex=
actly =0A> you are seeing (a hang, a BTX fault with a register dump,=0A> et=
c.).=0A=0AOne of the BTX fault shows the register dump in the attachment. =
=0AI hope this could help. Anyway, If I were to try to interpret =0Asuch re=
gister dump, where should I start? I understand x86/x86_64 =0Aassembly pret=
ty much, but I'm not quite well versed with the =0AFreeBSD code using it. =
=0A=0AThanks, =0A=0ADarmawan=0A=0A> =0A> -- =0A> John Baldwin=0A>=0A=0A=0A =
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