From owner-freebsd-hackers  Tue Jul 14 08:36:30 1998
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Date: Tue, 14 Jul 1998 11:36:18 -0400
From: Brian Cully <shmit@kublai.com>
To: Steven Kehlet <kehlet@dt.wdc.com>, Jonny <jvz@ns.nternet.net>
Cc: hackers@FreeBSD.ORG
Subject: Re: Assembly..
Reply-To: shmit@kublai.com
References: <Pine.BSF.3.96.980713191737.12005A-100000@ns.nternet.net> <Pine.GSO.3.96.980713171508.18643G-100000@hydra-X4>
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In-Reply-To: <Pine.GSO.3.96.980713171508.18643G-100000@hydra-X4>; from Steven Kehlet on Mon, Jul 13, 1998 at 05:55:06PM -0700
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On Mon, Jul 13, 1998 at 05:55:06PM -0700, Steven Kehlet wrote:
> (gdb) disass main
> Dump of assembler code for function main:
> 0x15b0 <main>:  pushl  $0x0
> 0x15b2 <main+2>:        leal   0x1,%eax
> 0x15b8 <main+8>:        pushl  0x1234
> 0x15be <main+14>:       lcall  0x7,0x0
> End of assembler dump.
> (gdb) 
> 
> ... just like it should.  Oh yeah, though, there's one more weird thing.
> Note that "pushl 0x1234" I stuck in there.  I found you need to
> push this garbage value onto the stack before doing the lcall.

I noticed the same thing when I was doing it with int $0x80, and not
lcall. What is the purpose of that value? From looking in
/sys/i386/i386/trap.c it appears to be ignored:

        params = (caddr_t)frame.tf_esp + sizeof(int);

Did it used to be used to hold an RTA or something?

-bjc

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