Franck Bui-Huu wrote: > 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". Could you check what "-march=mips32r2 -smartmips -mtune=4ksd" does? I expect it to have the same result than "-march=4ksd". Thiemo
