From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from oss.sgi.com (localhost [127.0.0.1]) by oss.sgi.com (8.12.3/8.12.3) with ESMTP id g5PEdInC022458 for ; Tue, 25 Jun 2002 07:39:18 -0700 Received: (from majordomo@localhost) by oss.sgi.com (8.12.3/8.12.3/Submit) id g5PEdITl022457 for linux-mips-outgoing; Tue, 25 Jun 2002 07:39:18 -0700 X-Authentication-Warning: oss.sgi.com: majordomo set sender to owner-linux-mips@oss.sgi.com using -f Received: from dea.linux-mips.net (c-180-196-147.ka.dial.de.ignite.net [62.180.196.147]) by oss.sgi.com (8.12.3/8.12.3) with SMTP id g5PEdCnC022454 for ; Tue, 25 Jun 2002 07:39:14 -0700 Received: (from ralf@localhost) by dea.linux-mips.net (8.11.6/8.11.6) id g5PEdf619590; Tue, 25 Jun 2002 16:39:41 +0200 Date: Tue, 25 Jun 2002 16:39:41 +0200 From: Ralf Baechle To: Carsten Langgaard Cc: "linux-mips@oss.sgi.com" Subject: Re: LTP testing Message-ID: <20020625163941.A19360@dea.linux-mips.net> References: <3D186E76.63B33B0E@mips.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <3D186E76.63B33B0E@mips.com>; from carstenl@mips.com on Tue, Jun 25, 2002 at 03:21:58PM +0200 X-Accept-Language: de,en,fr Sender: owner-linux-mips@oss.sgi.com Precedence: bulk On Tue, Jun 25, 2002 at 03:21:58PM +0200, Carsten Langgaard wrote: > The problem is that the code is called with $a0 = 0. So the 'sw v0, > 0(a0)' after the syscall generates a segmentation fault. > Why are the pipe syscall implemented this way, where we return the two > descriptors in v0 and v1 ? > Why doesn't the kernel do these stores (this way we can do an access > check, like i386 does) ? Because the interface we're using here is even lighter, even faster. Note that by the time when I decieded to use this interface this was potencially a huge difference as verify_area() was searching the mm AVL trees, so this interface was potenciall much faster by that time. Ralf