From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751075AbVHKPNS (ORCPT ); Thu, 11 Aug 2005 11:13:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751077AbVHKPNS (ORCPT ); Thu, 11 Aug 2005 11:13:18 -0400 Received: from nproxy.gmail.com ([64.233.182.205]:12155 "EHLO nproxy.gmail.com") by vger.kernel.org with ESMTP id S1751075AbVHKPNR convert rfc822-to-8bit (ORCPT ); Thu, 11 Aug 2005 11:13:17 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=gHnD88CzE1KaSMBpKK57eriUvchkRTnHUoLOWFbnO4hI7WgZuVE8b0uOZ+T6mbue63EPIRc0sRlwleTQefxA8Cup9GIGv8t54DotimoSzQSuzWgd8V8UdBqqW/NeT4buRoyKCCLk6eKSz81hby8stBI3vQONmDPf+4EQhwztTbo= Message-ID: <2cd57c90050811081374d7c4ef@mail.gmail.com> Date: Thu, 11 Aug 2005 23:13:13 +0800 From: Coywolf Qi Hunt To: Steven Rostedt Subject: Re: Need help in understanding x86 syscall Cc: "linux-os (Dick Johnson)" , linux-kernel@vger.kernel.org, Ukil a , 7eggert@gmx.de In-Reply-To: <1123770661.17269.59.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Content-Disposition: inline References: <4Ae73-6Mm-5@gated-at.bofh.it> <1123770661.17269.59.camel@localhost.localdomain> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 8/11/05, Steven Rostedt wrote: > On Thu, 2005-08-11 at 10:04 -0400, linux-os (Dick Johnson) wrote: > > Every interrupt software, or hardware, results in the branched > > procedure being executed with the interrupts OFF. That's why > > one of the first instructions in the kernel entry for a syscall > > is 'sti' to turn them back on. Look at entry.S, line 182. This > > occurs any time a trap occurs as well (Page 26-168, i486 > > Programmer's reference manual). FYI, this is helpful when > > designing/debugging complex interrupt-service routines since > > you can execute the interrupt with a software 'INT' instruction > > (with the correct offset from the IRQ you are using). The software > > doesn't 'know' where the interrupt came from, HW or SW. > > I'm looking at 2.6.13-rc6-git1 line 182 of entry.S and I don't see it. > Must be a different kernel. > > According to the documentation that I was looking at, a trap in x86 does > _not_ turn off interrupts. > ... > > I don't see a sti here. > > -- Steve He is RBJ, Richard B. Johnson, the LKML defacto official troll. -- Coywolf Qi Hunt http://ahbl.org/~coywolf/