From owner-freebsd-arch Sun Dec 5 8:29:50 1999 Delivered-To: freebsd-arch@freebsd.org Received: from ns1.yes.no (ns1.yes.no [195.204.136.10]) by hub.freebsd.org (Postfix) with ESMTP id 1959B151F0 for ; Sun, 5 Dec 1999 08:29:46 -0800 (PST) (envelope-from eivind@bitbox.follo.net) Received: from bitbox.follo.net (bitbox.follo.net [195.204.143.218]) by ns1.yes.no (8.9.3/8.9.3) with ESMTP id RAA09948 for ; Sun, 5 Dec 1999 17:29:45 +0100 (CET) Received: (from eivind@localhost) by bitbox.follo.net (8.8.8/8.8.6) id RAA02596 for freebsd-arch@freebsd.org; Sun, 5 Dec 1999 17:29:45 +0100 (MET) Received: from mailman.zeta.org.au (mailman.zeta.org.au [203.26.10.16]) by hub.freebsd.org (Postfix) with ESMTP id 6D160151F0 for ; Sun, 5 Dec 1999 08:29:37 -0800 (PST) (envelope-from bde@zeta.org.au) Received: from bde.zeta.org.au (beefcake.zeta.org.au [203.26.10.12]) by mailman.zeta.org.au (8.8.7/8.8.7) with ESMTP id DAA06604; Mon, 6 Dec 1999 03:34:30 +1100 Date: Mon, 6 Dec 1999 03:29:10 +1100 (EST) From: Bruce Evans X-Sender: bde@alphplex.bde.org To: Marcel Moolenaar Cc: Martin Cracauer , freebsd-arch@freebsd.org Subject: Re: cvs commit: src/sys/i386/include signal.h In-Reply-To: <384A3D54.3DFE76D6@scc.nl> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-arch@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Sun, 5 Dec 1999, Marcel Moolenaar wrote: > Martin Cracauer wrote: > > Decisions in order of importance: > > - Do you accept bumping mcontext_t to 512 bytes? > > No, I'll accept ucontext_t to be bumped to a nice round number (say 512 > bytes) and have the extra space used by mcontext_t :-) I don't want a round number (except maybe to a cache line or -mpreferred-stack boundary). Leaving space at the end of ucontext_t alone doesn't work because it is discontiguous with uc_mcontext. Leaving space in the middle of ucontext_t would be little better. OTOH, any expansion of mcontext_t while it is in the middle of ucontext_t would break binary compatibility. I think mcontext_t should go at the end of ucontext_t and most extensions should be in mcontext_t (just leave a few spares in ucontext_t and try not to use them). We would have to break binary compatibility again to move mcontext_t :-(. > > > - Do you like the bitmap scheme? > > Yes. It's quite common. Yes. > in mcontext_t: > ! int mc_fpemul[16]; /* Additional FPU emulator > status */ > ! int __morespare__[63]; /* For later additions, total = > 512 */ > > There's no need to rub it in :-) I prefer `__spare__' to make it clear > that it's not a regular field. I think Bruce would like you to use > `sc_spare'... I like struct member names to have prefixes. Prefixes are almost required in API headers to limit namespace pollution. When you have a prefix, using underscores is just and obfuscation. Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message