Hi. Some packages like setting -O3, or -O20 and -ffast-math, and override override CFLAGS because they know better. But most of the time these packages don't use -fomit-frame-pointer, which can have a significant effect on performance. It's usually not used for debugging reasons. Odd packages with problems, of which I know of none, will need -fno-omit-frame-pointer.
The painfull way to optimize is to build the package without setting CFLAGS to see what it wants to use, then modify CFLAGS to match. So, in gcc/common.opt under the line "fomit-frame-pointer" use: Common Report Var(flag_omit_frame_pointer) Init(1) The "Init(1)" sets -fomit-frame-pointer as the default. Use this with --with-arch=pentium4 (or whatever) and --with-cpu=pentium4 (or whatever) when building GCC. --with-arch sets the default -march=, and --with-cpu sets the default -mtune=. The combination of these should give close to optimal optimization without setting CFLAGS, allowing the multimedia packages to set whatever CFLAGS they like. Use this _after_ installing Glibc in chapter 6, because Glibc is picky about this. robert
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