> > Not that I'm a Linux hacker, but aren't those separate things? Can't you
> > compile with -march=4ksd to get the CPU-specific compiler optimisations,
> > but then use the more generic CONFIG_CPU_MIPSR2 and/or
> > CONFIG_CPU_SMARTMIPS to select the appropriate code inside the kernel
> > source (i.e. no need for CONFIG_CPU_4KSD)?
> >
>
> To use -march=4ksd, you need to tell to the building process that
> you're using a 4KSD cpu. The only way to do that is to define a new
> CPU_4KSD. But, if I understood mips configuration script, you cannot
> define CPU_4KSD _and_ CPU_MIPS32R2 at the same time; at least easily.
The point is not to set CPU_4KSD and CPU_MIPS32R2 at the same time,
the point is to not have to define CPU_4KSD *at all*, and use the combination
of MIPS32R2 and SMARTMIPS to drive the options, e.g.:
ifdef CONFIG_CPU_SMARTMIPS
cflags-$(CONFIG_CPU_MIPS32R1) += \
$(call set_gccflags,mips32,smartmips,4kec,mips3,mips2)\
-Os, -Wa,--trap
cflags-$(CONFIG_CPU_MIPS32R2) += \
$(call set_gccflags,4ksd,mips32r2,4kec,mips3,mips2) \
-Wa,--trap
else
cflags-$(CONFIG_CPU_MIPS32R1) += \
$(call set_gccflags,mips32,mips32,r4600,mips3,mips2) \
-Wa,--trap
cflags-$(CONFIG_CPU_MIPS32R2) += \
$(call set_gccflags,mips32r2,mips32r2,r4600,mips3,mips2)
\
-Wa,--trap
endif
That's almost certainly not the cleanest way to do it (and I really don't know
if the values I threw in for the MIPS32R1+SmartMIPS (e.g. 4KSc) combination
would actually work. I just want to point out that it isn't that hard to do.
Regards,
Kevin K.
