From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (from majordomo@localhost) by oss.sgi.com (8.11.2/8.11.3) id g0LJqxc09909 for linux-mips-outgoing; Mon, 21 Jan 2002 11:52:59 -0800 Received: from ocean.lucon.org (12-234-19-19.client.attbi.com [12.234.19.19]) by oss.sgi.com (8.11.2/8.11.3) with SMTP id g0LJquP09903 for ; Mon, 21 Jan 2002 11:52:56 -0800 Received: by ocean.lucon.org (Postfix, from userid 1000) id 6A812125C0; Mon, 21 Jan 2002 10:52:53 -0800 (PST) Date: Mon, 21 Jan 2002 10:52:53 -0800 From: "H . J . Lu" To: Ulrich Drepper Cc: "Maciej W. Rozycki" , "Kevin D. Kissell" , Machida Hiroyuki , GNU C Library , linux-mips@oss.sgi.com Subject: Re: thread-ready ABIs Message-ID: <20020121105253.B28087@lucon.org> References: <003701c1a25f$8abfc120$0deca8c0@Ulysses> <20020121102455.A27606@lucon.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from drepper@redhat.com on Mon, Jan 21, 2002 at 10:36:26AM -0800 Sender: owner-linux-mips@oss.sgi.com Precedence: bulk On Mon, Jan 21, 2002 at 10:36:26AM -0800, Ulrich Drepper wrote: > "H . J . Lu" writes: > > > Ulrich, should applciations have access to thread register directly? > > It doesn't matter. The value isn't changed in the lifetime of a > thread. So the overhead of a syscall wouldn't be too much. And > protection against programs overwriting the register isn't necessary. > It's the program's fault if that happens. Thq question is if we should reserve $23 outside of glibc. $23 is a saved register in the MIPS ABI. It doesn't change across function calls. If applications outside of glibc don't need to access the thread register directly, that means $23 can be used as a saved register. We don't have to change anything when compiling applications. We only need to compile glibc with $23 reserved as the thread register. H.J.