From owner-freebsd-questions@FreeBSD.ORG  Sat Nov 11 18:55:31 2006
Return-Path: <owner-freebsd-questions@FreeBSD.ORG>
X-Original-To: freebsd-questions@freebsd.org
Delivered-To: freebsd-questions@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 7AEEF16A40F
	for <freebsd-questions@freebsd.org>;
	Sat, 11 Nov 2006 18:55:31 +0000 (UTC)
	(envelope-from trowa-4@yahoo.com.tw)
Received: from web72013.mail.tp2.yahoo.com (web72013.mail.tp2.yahoo.com
	[203.188.200.43])
	by mx1.FreeBSD.org (Postfix) with SMTP id A6A9243D45
	for <freebsd-questions@freebsd.org>;
	Sat, 11 Nov 2006 18:55:30 +0000 (GMT)
	(envelope-from trowa-4@yahoo.com.tw)
Received: (qmail 17558 invoked by uid 60001); 11 Nov 2006 18:55:29 -0000
DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.tw;
	h=X-YMail-OSG:Received:Date:From:Subject:To:MIME-Version:Content-Type:Content-Transfer-Encoding:Message-ID;
	b=FfcR+Gj+3UJIW3Ud57h8FcRAGZn7by33omgnHb2RYzHmHpRUye7uMcrxpQQhQre8GtV9OhxhkqP0vtZw0FuxUQ9YMzvxhgDK54JHWQw3tOsKPtKzBZvvEpFgnwhFxpCQNTN7b0ZbBYCVp/pFsty6+UdhQp4y7fMOtUcydzyiMcM=;
X-YMail-OSG: lGzO86QVM1kOmMg1Khka.ke1M8dm8vTAch7.2IOr0LtDJbX6p.ZfSCfHsYdUxo2BbvcWJ_PNmXi7CnP5xXhjy2WidaiIpykwGSSz_yHJwYGmjPJ2eqUsSN1U1iGzDK.CqrBleLFF8wFm81v4rNMGkZmMteBvMFnrv4attg9j4DCRa1NRHbGrPYO7qxNk
Received: from [61.56.138.188] by web72013.mail.tp2.yahoo.com via HTTP;
	Sun, 12 Nov 2006 02:55:29 CST
Date: Sun, 12 Nov 2006 02:55:29 +0800 (CST)
From: "Wenyen, Shih" <trowa-4@yahoo.com.tw>
To: freebsd-questions@freebsd.org
MIME-Version: 1.0
Content-Type: text/plain; charset=big5
Content-Transfer-Encoding: 8bit
Message-ID: <562718.15358.qm@web72013.mail.tp2.yahoo.com>
X-Mailman-Approved-At: Sun, 12 Nov 2006 05:18:31 +0000
Subject: signal design questions
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions>
List-Post: <mailto:freebsd-questions@freebsd.org>
List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sat, 11 Nov 2006 18:55:31 -0000

Hi all,
   I have some questions.
   (1)  I know how to delivery of a signal to a
process.

      1. The kernel places a signal context on the
user's stack.(user level)
      2. The kernel places a signal-handler frame on
the user's stack.(kernel level)
      3. The user's signal handler returns to the
sigtramp() routine, which pops the signal-handler
context from the user's stack.(user level)
      4. The sigtramp() routine finishes by calling
the sigreturn system call.

      But, why don't implement signal handler routine
in kernel level? Are there having any ideas to
implement signal handler routine in kernel level?


    (2) The system-call exit code first checks for a
posted signal and check to see whether any process has
a priority higher than that of the currently running
process.
    But, I don't know the signal be checked when
returning from kernel mode to user mode.

    Anyone have any other methods to checked the
signal in the other occasion ? 
     
Thanks,

Wenyen

___________________________________________________ 
 您的生活即時通 － 溝通、娛樂、生活、工作一次搞定！ 
 http://messenger.yahoo.com.tw/