From: David Gordon Hogan <dhog@plan9.bell-labs.com>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] booting an AlphaPC 164
Date: Mon, 25 Jun 2001 15:22:53 -0400 [thread overview]
Message-ID: <20010625192257.84863199FF@mail.cse.psu.edu> (raw)
> If i understand the boot process correctly, it has just jumped into
> _main() in/sys/src/9/alphapc/l.s from gokernel() in /sys/src/9/boot/alphapc/exec.c
> By adding RET to various points of _main() in l.s, i am thinking it is hanging
> at the spot marked:
> TEXT _main(SB), $-8
> MOVQ $setSB(SB), R29
> MOVQ R29, R16
> CALL_PAL $PALwrkgp
> MOVQ $mach0(SB), R(MACH)
> MOVQ $(BY2PG-8)(R(MACH)), R30 <-------------
> MOVQ R31, R(USER)
> MOVQ R31, 0(R(MACH))
>
> If i understand correctly this just sets the stack pointer to last quadword
> of the page containing the mach structure.
Although the RET instruction doesn't use SP itself, the caller isn't going to
be too happy after you change it. Use the "CALL_PAL $PALhalt" instruction
to find out where it's really hanging. If it makes it to C, you can insert calls
to firmware().
> We get the same behavior w/ both the terminal and cpu kernels, and
> also the same if we try it on an ev6 machine. I found a post about
> using the -x flag to 7l, but that does not seem to help.
That's only neccessary for older CPUs. You'll be taking a significant
performance hit by using it otherwise, and some of the device drivers
may not work.
next reply other threads:[~2001-06-25 19:22 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-06-25 19:22 David Gordon Hogan [this message]
-- strict thread matches above, loose matches on Subject: below --
2001-06-25 18:54 dpx
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