Date: Tue, 11 Feb 2003 11:05:58 +0100 From: Stijn Hoop <stijn@win.tue.nl> To: Alfred Perlstein <bright@mu.org> Cc: "Thomas E. Zander" <riggs@rrr.de>, Alexandr Kovalenko <never@nevermind.kiev.ua>, Oliver Braun <obraun@freebsd.org>, ports-committers@freebsd.org, cvs-ports@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: ports/multimedia/mplayer Makefile distinfo pkg-plist ports/multimedia/mplayer/files patch-ad Message-ID: <20030211100558.GB17571@pcwin002.win.tue.nl> In-Reply-To: <20030211100013.GO88781@elvis.mu.org> References: <200302101928.h1AJS6Gs088748@repoman.freebsd.org> <20030210200115.GA832@nevermind.kiev.ua> <20030211013436.GB576@trillian.mugiri.au> <20030211095745.GA17571@pcwin002.win.tue.nl> <20030211100013.GO88781@elvis.mu.org>
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[-- Attachment #1 --] On Tue, Feb 11, 2003 at 02:00:13AM -0800, Alfred Perlstein wrote: > * Stijn Hoop <stijn@win.tue.nl> [030211 01:58] wrote: > > On Tue, Feb 11, 2003 at 09:34:36AM +0800, Thomas E. Zander wrote: > > > Am Mon, dem 10. Feb 2003, um 22:01 +0200 Uhr schrubte Alexandr Kovalenko: > > > > We should also note that if you are planning to play QT movies, you > > > > should add CPU_ENABLE_SSE to your kernel so that mplayer will not crash > > > > attempting to play it (looks like either mplayer or QT win32 libs can't > > > > detect if SSE is enabled). > > > > > > No, that is not a qt-specific problem. > > > Mplayer checks which cpu it is running on and assumes (as I would do if > > > I were a program :-) ) that it can use SSE if it is a SSE-capable CPU. > > > > I think this is a bad assumption. There should be a mechanism for mplayer > > to detect whether it can use SSE instructions without 'guessing' by > > checking the CPU type. As another poster asked, how do I know I can > > use the option? It's not exactly common knowledge that the kernel option > > might be needed. > > > > But I also think it is strange that the fact that SSE instructions are > > available cannot be detected (and used) at runtime by the kernel. Is > > this unwise to do for performance reasons? Anyone care to elaborate? > > > > A quick grep through /usr/src shows that there are not too many places > > that this option is used although it seems to affect process > > register storage, so I imagine it could be a performance hit if > > another check is needed per process context switch. > > > > However I'm absolutely no kernel developer, so this is mostly guessing. > > Anyone with more clue reading this? > > I would seem trivial to add a sysctl under machdep to tell userland > if sse is available and configured. OK, that would solve this problem, but what about my other question? Why not just detect if SSE is available, and use it, at runtime? Why do we need a kernel option for this? --Stijn -- I really hate this damned machine I wish that they would sell it. It never does quite what I want But only what I tell it. [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (FreeBSD) iD8DBQE+SMsGY3r/tLQmfWcRAr08AJ4hchFYl6xiYnPuEwdhpF0Fv3ZHdACghj+s zpqn6GYKJUkg4QV8LaXZdU4= =9eAz -----END PGP SIGNATURE-----
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