"Vincent Blondel" <vincent_at_xtra-net.org> writes: > So in this context, I use 'CFLAGS= -O2 -pipe -fno-strict-aliasing' > and 'CPUTYPE?=athlon-xp' for compiling kernel but when I look at > file /usr/src/sys/conf/kern.mk I see all kind of mmx/3dnow/sse/sse2 > are disabled [...] We don't want to use floating point within the kernel, for a variety of reasons (one of them being that saving and restoring the floating point context when switching in and out of the kernel is very expensive). > So, finally, there is something I don't understand, what is the goal > of 'CPU_ENABLE_SSE' [...] The (now standard) CPU_ENABLE_SSE option adds code to save / restore SSE registers when necesary. This allows userland applications to use SSE without getting clobbering eachother's data. DES -- Dag-Erling Smørgrav - des_at_des.noReceived on Mon May 08 2006 - 01:13:07 UTC
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