Date: Tue, 11 Feb 2003 02:00:13 -0800 From: Alfred Perlstein <bright@mu.org> To: Stijn Hoop <stijn@win.tue.nl> 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: <20030211100013.GO88781@elvis.mu.org> In-Reply-To: <20030211095745.GA17571@pcwin002.win.tue.nl> References: <200302101928.h1AJS6Gs088748@repoman.freebsd.org> <20030210200115.GA832@nevermind.kiev.ua> <20030211013436.GB576@trillian.mugiri.au> <20030211095745.GA17571@pcwin002.win.tue.nl>
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* 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. -Alfred To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-ports" in the body of the message
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