2006/1/27, Kevin D. Kissell <kevink@xxxxxxxx>: > > > Configuration hacks that are specific to a single core create cruft and > > > maintenence problems. As I said yesterday, I think we'd be much better > > > off to have a CONFIG_CPU_MIPS_SMALL or some such option > > > that could cause -Os to be used, allow branch-likelies, etc. The optimizations > > > under discussion aren't at all specific to the 4KSd, > > > > no some are. As we said previously: > > > > 1/ sizeof(vmlinux-mips32r2-Os) > sizeof(vmlinux-4ksd-Os) > > 2/ with -march=4ksd can do (slightly) better optimizations. > > This is very possibly due to the compiler knowing about the SmartMIPS > scaled, indexed load instructions, which were added to improve virtual > machine performance, but which also save on address calculation instructions. > If -march=mips32r2 combined with -msmartmips and -Os don't produce > pretty much the same result as -march=4ksd, I'd be interested in knowing > why. well, Nigel gave us some answers here, no ? I'm not sure it's a good idea to use -march=mips32r2 whatever the mips32r2 cpu is used. Even if the gain is small, we should use a specific cpu description. If the configuration makes it hard, it should be reworked, isn't it ? > Regardless, if this is what's going on, there really is no other core > in production today that will run that code. But that doesn't mean > that there won't be others in the future. > > All I'm really trying to do here is to get away from core-specific config > cruft. If the best result under-the-hood for 4KSd is obtained by using > -march=4ksd, that's what people should get, but I'd rather that users > and maintainers saw that as a choice of MIPS32R2+SmartMIPS rather > than a choice of 4KSd as a one-off. > Ok what about this patch. It allows to choose a specific cpu when MIPS32R2 architecture is selected ? diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 8b9002a..a6d168c 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -1290,6 +1302,30 @@ config SYS_HAS_CPU_RM9000 config SYS_HAS_CPU_SB1 bool +# +# CPU model tuning. +# +choice + prompt "CPU model" + default CPU_GENERIC + help + When configuring kernel building to MIPS32 architecture, + whatever the release number, it can be interesting to narrow + your choice for speed and size optimizations. + +config CPU_GENERIC + bool "Generic" + help + It's safe to select this if your CPU model doesn't appear in the list. + +config CPU_4KSD + bool "4KSD" + depends on SYS_HAS_CPU_MIPS32_R2 + help + MIPS Technologies 4KSd-series processors. + +endchoice + endmenu # diff --git a/arch/mips/Makefile b/arch/mips/Makefile index bc99c2d..c11df11 100644 --- a/arch/mips/Makefile +++ b/arch/mips/Makefile @@ -165,82 +167,92 @@ echo $$gcc_abi $$gcc_opt$$gcc_cpu $$gcc_ # # CPU-dependent compiler/assembler options for optimization. # -cflags-$(CONFIG_CPU_R3000) += \ + +__cflags-$(CONFIG_CPU_R3000) += \ $(call set_gccflags,r3000,mips1,r3000,mips1,mips1) -cflags-$(CONFIG_CPU_TX39XX) += \ +__cflags-$(CONFIG_CPU_TX39XX) += \ $(call set_gccflags,r3900,mips1,r3000,mips1,mips1) -cflags-$(CONFIG_CPU_R6000) += \ +__cflags-$(CONFIG_CPU_R6000) += \ $(call set_gccflags,r6000,mips2,r6000,mips2,mips2) \ -Wa,--trap -cflags-$(CONFIG_CPU_R4300) += \ +__cflags-$(CONFIG_CPU_R4300) += \ $(call set_gccflags,r4300,mips3,r4300,mips3,mips2) \ -Wa,--trap -cflags-$(CONFIG_CPU_VR41XX) += \ +__cflags-$(CONFIG_CPU_VR41XX) += \ $(call set_gccflags,r4100,mips3,r4600,mips3,mips2) \ -Wa,--trap -cflags-$(CONFIG_CPU_R4X00) += \ +__cflags-$(CONFIG_CPU_R4X00) += \ $(call set_gccflags,r4600,mips3,r4600,mips3,mips2) \ -Wa,--trap -cflags-$(CONFIG_CPU_TX49XX) += \ +__cflags-$(CONFIG_CPU_TX49XX) += \ $(call set_gccflags,r4600,mips3,r4600,mips3,mips2) \ -Wa,--trap -cflags-$(CONFIG_CPU_MIPS32_R1) += \ - $(call set_gccflags,mips32,mips32,r4600,mips3,mips2) \ - -Wa,--trap - -cflags-$(CONFIG_CPU_MIPS32_R2) += \ - $(call set_gccflags,mips32r2,mips32r2,r4600,mips3,mips2) \ - -Wa,--trap - -cflags-$(CONFIG_CPU_MIPS64_R1) += \ - $(call set_gccflags,mips64,mips64,r4600,mips3,mips2) \ - -Wa,--trap - -cflags-$(CONFIG_CPU_MIPS64_R2) += \ - $(call set_gccflags,mips64r2,mips64r2,r4600,mips3,mips2) \ - -Wa,--trap - -cflags-$(CONFIG_CPU_R5000) += \ +__cflags-$(CONFIG_CPU_R5000) += \ $(call set_gccflags,r5000,mips4,r5000,mips4,mips2) \ -Wa,--trap -cflags-$(CONFIG_CPU_R5432) += \ +__cflags-$(CONFIG_CPU_R5432) += \ $(call set_gccflags,r5400,mips4,r5000,mips4,mips2) \ -Wa,--trap -cflags-$(CONFIG_CPU_NEVADA) += \ +__cflags-$(CONFIG_CPU_NEVADA) += \ $(call set_gccflags,rm5200,mips4,r5000,mips4,mips2) \ -Wa,--trap # $(call cc-option,-mmad) -cflags-$(CONFIG_CPU_RM7000) += \ +__cflags-$(CONFIG_CPU_RM7000) += \ $(call set_gccflags,rm7000,mips4,r5000,mips4,mips2) \ -Wa,--trap -cflags-$(CONFIG_CPU_RM9000) += \ +__cflags-$(CONFIG_CPU_RM9000) += \ $(call set_gccflags,rm9000,mips4,r5000,mips4,mips2) \ -Wa,--trap -cflags-$(CONFIG_CPU_SB1) += \ +__cflags-$(CONFIG_CPU_SB1) += \ $(call set_gccflags,sb1,mips64,r5000,mips4,mips2) \ -Wa,--trap -cflags-$(CONFIG_CPU_R8000) += \ +__cflags-$(CONFIG_CPU_R8000) += \ $(call set_gccflags,r8000,mips4,r8000,mips4,mips2) \ -Wa,--trap -cflags-$(CONFIG_CPU_R10000) += \ +__cflags-$(CONFIG_CPU_R10000) += \ $(call set_gccflags,r10000,mips4,r8000,mips4,mips2) \ -Wa,--trap +__cflags-$(CONFIG_CPU_4KSD) += \ + $(call set_gccflags,4ksd,mips32r2,4kec,mips32r2) \ + -Wa,--trap + +# Fallback options for MIPS32 architectures +ifndef __cflags-y +__cflags-$(CONFIG_CPU_MIPS32_R1) += \ + $(call set_gccflags,mips32,mips32,r4600,mips3,mips2) \ + -Wa,--trap + +__cflags-$(CONFIG_CPU_MIPS32_R2) += \ + $(call set_gccflags,mips32r2,mips32r2,r4600,mips3,mips2) \ + -Wa,--trap + +__cflags-$(CONFIG_CPU_MIPS64_R1) += \ + $(call set_gccflags,mips64,mips64,r4600,mips3,mips2) \ + -Wa,--trap + +__cflags-$(CONFIG_CPU_MIPS64_R2) += \ + $(call set_gccflags,mips64r2,mips64r2,r4600,mips3,mips2) \ + -Wa,--trap +endif + +cflags-y += $(__cflags-y) + ifdef CONFIG_CPU_SB1 ifdef CONFIG_SB1_PASS_1_WORKAROUNDS MODFLAGS += -msb1-pass1-workarounds
