> >>>> Are vr41xx plain ISA I or crippled ISA II+ CPUs?
> >>>
> >>> Actually, they are crippled MIPS III+ 64-bit CPUs
> >>
> >>
> >> Then an ll/sc and lld/scd emulation seems to be most appropriate here.
I
> >> don't think we want to add _test_and_set() to mips64*-linux.
> >
> >All the cases I've seen have been for 32-bit kernels. A 64-bit PDA kernel
seems like a wee tiny bit of overkill
>
> I've been asked about running 64 bit binaries on a VR4121.
Being able to use all 64-bits of the registers is a huge win for
certain embedded/handheld applications, even if 64-bit addressing
is worse than useless. It's unfortunate that the original R4000 merged
the enabling of 64-bit data types with the generation of 64-bit addresses.
The newer MIPS64 CPUs have a bit in the Status register to
enable the data types without enabling the addresses.
I don't know that NEC has implemented this for the VR41xx
family, but they really should. And fix ll/sc while they are at it. ;-)
Kevin K.
