Franck Bui-Huu wrote:
Thiemo Seufer wrote:
Could you check what "-march=mips32r2 -smartmips -mtune=4ksd" does?
I expect it to have the same result than "-march=4ksd".
OK, I give it a try and here are some figures:
$ mipsel-linux-size mipssde-6.05.00-20061023/vmlinux~*
text data bss dec hex filename
1446130 58456 93056 1597642 1860ca mipssde-6.05.00-20061023/vmlinux~4ksd
1472034 58456 93056 1623546 18c5fa mipssde-6.05.00-20061023/vmlinux~mips32r2-smartmips
1446130 58456 93056 1597642 1860ca mipssde-6.05.00-20061023/vmlinux~mips32r2-smartmips-mtune4ksd
So you're right "-march=mips32r2 -smartmips -mtune=4ksd" gives the
same result as "-march=4ksd"
IIRC that should be -msmartmips, not -smartmips.
And the extra space given by "-march=mips32r2 -smartmips" is coming
from some additional nop instructions:
$ mipsel-linux-objdump -D vmlinux~mips32r2-smartmips > vmlinux~mips32r2-smartmips.S
$ mipsel-linux-objdump -D vmlinux~4ksd > vmlinux~4ksd.S
$ grep -c nop *.S
vmlinux~4ksd.S:18708
vmlinux~mips32r2-smartmips.S:27895
It seems that these extra nops are used for load delays. For example:
vmlinux~4ksd.S:
--------------
<snip>
c00008b4: 8fa40040 lw a0,64(sp)
c00008b8: 27a40018 addiu a0,sp,24
c00008bc: 0c000148 jal c0000520 <try_name>
<snip>
vmlinux~mips32r2-smartmips.S:
---------------------------
c00008b8: 8fa40040 lw a0,64(sp)
c00008bc: 00000000 nop
c00008c0: 27a40018 addiu a0,sp,24
c00008c4: 0c000148 jal c0000520 <try_name>
That's weird: load delay slots should only be required by -march=mips1
(or no -march)
Are you sure that the -march=mips32r2 option is really getting passed to
the compiler and assembler?
Nigel
