Date: Fri, 19 Mar 2010 18:22:49 +0200 From: Valentin Nechayev <netch@netch.kiev.ua> To: Ivan Voras <ivoras@freebsd.org> Cc: svn-src-head@freebsd.org, Garrett Cooper <yanefbsd@gmail.com>, svn-src-all@freebsd.org, src-committers@freebsd.org, Xin LI <delphij@freebsd.org> Subject: Re: I486_CPU and I586_CPU removed from GENERIC kernel [was Re: svn commit: r205307 - head/sys/i386/conf] Message-ID: <20100319162249.GD67820@netch.kiev.ua> In-Reply-To: <9bbcef731003190913k4f3afbd8mb4e767c40433be8e@mail.gmail.com> References: <7d6fde3d1003182333m336d52fbh987035a21568250d@mail.gmail.com> <9bbcef731003190913k4f3afbd8mb4e767c40433be8e@mail.gmail.com>
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Fri, Mar 19, 2010 at 17:13:00, ivoras wrote about "Re: I486_CPU and I586_CPU removed from GENERIC kernel [was Re: svn commit: r205307 - head/sys/i386/conf]": > SSE in the userland you mean? Regardless, I don't think there is now > reason for compiling everything as for i386. E.g. why not add at least > -mtune=generic or even also -march=i686 to default gcc options? > > http://gcc.gnu.org/onlinedocs/gcc/i386-and-x86_002d64-Options.html Having userland compiled with i686 will give the same effect as i686-only kernel: it won't boot on machines which doesn't conform to. If it is supposed to boot on i486 and higher, no more than -march=i486 can be used. OTOH it would be quite popular for most desktops and big servers to orient to fresh hardware, so one can (if having enough resources) to split targets: 1) - for most, which would have e.g. CFLAGS=... -march=pentium3 -mmmx -msse -mfpmath=sse,387 -mtune=generic COPTFLAGS=... -march=pentium3 -mtune=generic 2) for small/embedded/etc. with defaults to i486 and make separate binary distributions for them. OT3H it isn't proven to give real effect except very limited cases (CPU-intensive (mplayer, etc.), graphics-intensive apps (KDE)). Mplayer usually uses differently compiled modules for different CPUs. There are quite few applications which can get real benefit. -netch-
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