Re: gcc: mips32 vs mips3

[Marian Jancar <m.jancar@satca.net>]

Ralf Baechle wrote:
> On Fri, Mar 06, 2009 at 05:55:10PM +0100, Marian Jancar wrote:
> 
>> which option is supposed to compile faster code, -mips3 or -mips32?
> 
> That question doesn't quite make sense.   A MIPS32 processor can't execute
> MIPS III code and a MIPS III processor can't execute MIPS32 code.  Only a
> MIPS64 processor could execute code compiled for either MIPS32 or MIPS III.
> So choose the option to match the architecture of your processor.

The processor in question is the processos in the Atheros 802.11 SoC 
AR5312, 4Kc AFAIK.
OpenWRT uses -mips32 for this target but the GPL SDK for NanoStation
uses -march=r4600. Both options produce code that runs without oops
or any other immediately manifested issues.
So you are right, the correct question is "-mips32 vs -march=r4600".
I got confused because I left some bits compiled with -march=4600 when
recompiling with -mips32 and gcc complained about it being compiled
for MIPS III when linking.

Marian

# cat /proc/cpuinfo
system type             : Atheros AR2313
processor               : 0
cpu model               : MIPS 4Kc V0.10
BogoMIPS                : 179.40
wait instruction        : yes
microsecond timers      : yes
tlb_entries             : 16
extra interrupt vector  : yes
hardware watchpoint     : yes
ASEs implemented        :
VCED exceptions         : not available
VCEI exceptions         : not available