Dear Jan,
Jan Rovins wrote:
I am setting up for some experimental builds for a 64 bit Mips processor,
I see that there are options for 64bit processors in both the mips &
mips64 architecture options.
The mips selection lists options like these:
mips64 "MIPS Instruction Set Architecture 64Bit" \
r6000 "MIPS r6000 processor" \
r8000 "MIPS r8000 processor" \
The mips64 lists these options
generic "No special optimisation" \
r5000 "Build for R5000 CPU" \
r6000 "Build for R6000 CPU" \
r8000 "Build for R8000 CPU"
Question 1:
are the mips->mips64 and the mips64->generic options equivalent?
They are not equivalent, for mips builds (even optimized for a generic,
newer 64bit CPU) you will always get 32bit builds, while for mips64
builds you will get 64bit builds. Like in the x86 world where you
can still build 32bit software for latest Intel i7 / AMD Opteron silicon.
are the mips->r6000 and the mips64->r6000 options equivalent?
are the mips->r8000 and the mips64->r8000 options equivalent?
As above, with mips as base architecture you will get 32bit binaries,
while with the mips64 base architecture you will get 64 bit binaries.
The same applies for our x86 vs x86-64, powerpc vs powerpc64 or
sparc vs sparc64 choices.
if not, how are they different? (does the mips arch build 32-bit code
that runs on the 64 bit processors?)
Yes, so it should be.
Question 2: If they are equivalent, is one preferred over the other?
They are not equivalent, but one might want to run 32bit binaries
for compatibility or performance even on 64bit capable chips.
Question3:
The Mips universe offers 3 different abi's n32,o32, and n64. is
there a way to specify the abi in ones project? or by specifying
multilib, do we automatically get both the n32 & n64 abi libs built?
I'm unsure about n32 vs. o32, it's some days since I worked with a MIPS
in a project. I think t2's mips is currently hardwired to either n32 or o32,
the one that worked stable or so at that time.
mips64 build n64 with either n32 or o32 compatibility C and C++
library.
Hope this helps,
René
--
René Rebe - ExactCODE GmbH - Europe, Germany, Berlin
http://exactcode.de | http://t2-project.org | http://rene.rebe.name
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