From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753071Ab0CWX5L (ORCPT ); Tue, 23 Mar 2010 19:57:11 -0400 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:42416 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752792Ab0CWX5C (ORCPT ); Tue, 23 Mar 2010 19:57:02 -0400 Date: Tue, 23 Mar 2010 20:53:42 +0000 From: Russell King - ARM Linux To: Christoffer Dall Cc: containers , linux-arm-kernel , linux-kernel , Roland McGrath Subject: Re: [C/R ARM][PATCH 1/3] ARM: Rudimentary syscall interfaces Message-ID: <20100323205342.GA19572@n2100.arm.linux.org.uk> References: <1269219965-23923-1-git-send-email-christofferdall@christofferdall.dk> <1269219965-23923-2-git-send-email-christofferdall@christofferdall.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1269219965-23923-2-git-send-email-christofferdall@christofferdall.dk> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Mar 21, 2010 at 09:06:03PM -0400, Christoffer Dall wrote: > This small commit introduces a global state of system calls for ARM > making it possible for a debugger or checkpointing to gain information > about another process' state with respect to system calls. I don't particularly like the idea that we always store the syscall number to memory for every system call, whether the stored version is used or not. Since ARM caches are generally not write allocate, this means mostly write-only variables can have a higher than expected expense. Is there not some thread flag which can be checked to see if we need to store the syscall number? From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@arm.linux.org.uk (Russell King - ARM Linux) Date: Tue, 23 Mar 2010 20:53:42 +0000 Subject: [C/R ARM][PATCH 1/3] ARM: Rudimentary syscall interfaces In-Reply-To: <1269219965-23923-2-git-send-email-christofferdall@christofferdall.dk> References: <1269219965-23923-1-git-send-email-christofferdall@christofferdall.dk> <1269219965-23923-2-git-send-email-christofferdall@christofferdall.dk> Message-ID: <20100323205342.GA19572@n2100.arm.linux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sun, Mar 21, 2010 at 09:06:03PM -0400, Christoffer Dall wrote: > This small commit introduces a global state of system calls for ARM > making it possible for a debugger or checkpointing to gain information > about another process' state with respect to system calls. I don't particularly like the idea that we always store the syscall number to memory for every system call, whether the stored version is used or not. Since ARM caches are generally not write allocate, this means mostly write-only variables can have a higher than expected expense. Is there not some thread flag which can be checked to see if we need to store the syscall number?