On Dec 17, 2007, at 4:43 PM, Rick Mann wrote:
Hi. I've built an xscale-elf toolchain from gcc-4.2.2,
binutils-2.17, newlib-1.15.0. I've used the exact same build
procedure on both Mac OS X 10.5 (gcc-4.0.1-based) and Cygwin (gcc
3.4-based).
Then I built our code and stripped the resulting binary with objcopy
on each platform.
Both binaries seem to run the same.
However, cmp shows many differences between the two resulting
binaries. Here are a few:
$ cmp -l ~/h h | head -10
77 21 63
81 32 74
85 27 71
97 370 220
98 162 163
101 134 364
105 134 364
141 4 15
143 55 240
144 345 341
Are these differences something to worry about?
I've disassembled the .elf files, and here are some of the differences:
Mac OS X:
8000804c <loop>:
8000804c: eb00a933 bl 80032520 <_init>
80008050: eb000c3c bl 8000b148 <main>
80008054: eb00a939 bl 80032540 <_fini>
80008058: eaffffe8 b 80008000 <//.>
8000805c: e89da800 ldmia sp, {fp, sp, pc}
...
80008060 <bss_start>:
80008060: 80047390 mulhi r4, r0, r3
80008064 <bss_end>:
80008064: 803a51f4 ldrhisht r5, [sl], -r4
Cygwin:
8000804c <loop>:
8000804c: eb00a911 bl 80032498 <_init>
80008050: eb000c1a bl 8000b0c0 <main>
80008054: eb00a917 bl 800324b8 <_fini>
80008058: eaffffe8 b 80008000 <//.>
8000805c: e89da800 ldmia sp, {fp, sp, pc}
...
80008060 <bss_start>:
80008060: 800472f8 strhid r7, [r4], -r8
80008064 <bss_end>:
80008064: 803a515c eorhis r5, sl, ip, asr r1
Some functions are placed in different order, too.
I'm trying to ensure that all our developers build identical binaries.
TIA,
--
Rick
