From owner-freebsd-hackers@FreeBSD.ORG  Mon Jul 24 08:04:30 2006
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
X-Original-To: freebsd-hackers@freebsd.org
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 0786316A4E1;
	Mon, 24 Jul 2006 08:04:30 +0000 (UTC)
	(envelope-from xdivac02@stud.fit.vutbr.cz)
Received: from eva.fit.vutbr.cz (eva.fit.vutbr.cz [147.229.10.14])
	by mx1.FreeBSD.org (Postfix) with ESMTP id C1CD943D5A;
	Mon, 24 Jul 2006 08:04:16 +0000 (GMT)
	(envelope-from xdivac02@stud.fit.vutbr.cz)
Received: from eva.fit.vutbr.cz (localhost [127.0.0.1])
	by eva.fit.vutbr.cz (envelope-from xdivac02@eva.fit.vutbr.cz)
	(8.13.7/8.13.7) with ESMTP id k6O84Apx039886
	(version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NO);
	Mon, 24 Jul 2006 10:04:10 +0200 (CEST)
Received: (from xdivac02@localhost)
	by eva.fit.vutbr.cz (8.13.7/8.13.3/Submit) id k6O84Acn039884;
	Mon, 24 Jul 2006 10:04:10 +0200 (CEST)
Date: Mon, 24 Jul 2006 10:04:10 +0200
From: Divacky Roman <xdivac02@stud.fit.vutbr.cz>
To: Attilio Rao <attilio@freebsd.org>
Message-ID: <20060724080410.GA39744@stud.fit.vutbr.cz>
References: <20060723112332.GA83581@stud.fit.vutbr.cz>
	<3bbf2fe10607231418y58510d02ua208acbb44ea9f8c@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <3bbf2fe10607231418y58510d02ua208acbb44ea9f8c@mail.gmail.com>
User-Agent: Mutt/1.4.2i
X-Scanned-By: MIMEDefang 2.54 on 147.229.10.14
Cc: freebsd-hackers@freebsd.org
Subject: Re: i386 registers during a syscall
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>, 
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 24 Jul 2006 08:04:30 -0000

On Sun, Jul 23, 2006 at 11:18:56PM +0200, Attilio Rao wrote:
> 2006/7/23, Divacky Roman <xdivac02@stud.fit.vutbr.cz>:
> >hi,
> >
> >I need to get content of %esi register as it was during a syscall. Should 
> >I get
> >this info from td->td_pcb->pcb_esi or td->td_frame->tf_esi?
> >
> >Is it so that trapframe is "content of registers when entering a kernel" 
> >and
> >pcb is "when leaving a kernel" ?
> >
> >thnx for info
> 
> pcb and trapframe are used for very different purposes.
> 
> The trapframe is built into the exception handler and it is used as
> 'registers gate' from userspace/kernelspace.
> 
> The pcb (process control block) is used to handle registers saving
> during a context switch, so it seems completely ortogonal to your
> problem.
> 
> BTW, it's unclear to me what do you need...

mov $123, %esi
int $0x80		; syscall

I need the value of %esi (ie. 123)

is td->td_frame->tf_esi what I need?

thnx

roman