Maciej W. Rozycki wrote: > On Tue, 9 Oct 2007, Franck Bui-Huu wrote: > >>> What would be the gain for the kernel from using "-march=4ksd" rather >>> than "-march=mips32r2"? >>> >> It actually results in a kernel image ~30kbytes smaller for the former >> case. It has been discussed sometimes ago on this list. I'm sorry but >> I don't know why... > > Perhaps the pipeline description for the 4KSd CPU is different from the > default for the MIPS32r2 ISA. Barring a study of GCC sources, if that > really troubles you, you could build the same version of the kernel with > these options: > > 1. "-march=mips32r2" > > 2. "-march=4ksd" > > 3. "-march=mips32r2 -mtune=4ksd" > > and compare the results. I expect the results of #2 and #3 to be the same > and it would just back up my suggestion about keeping CPU-specific > optimisations separate from the CPU selection. I think you misunderstood me, my own fault: the kernel was smaller with "-march=4ksd". It was bigger when using "-march=mips32r2 -smartmips". I was using SDE gcc. Franck
