Hi,
I am trying to get a piece of software running on an ARM Evaluator board
without an operating system. I have been using Code Worrier and AXD from the
ARM Developer Suite as well as GNU GCC to do the development. Just to check
that the GNU cross compiler is working ok i wrote a simple 'Hello world'
program and compiled it using CodeWorrier and GCC. The CodeWorrier compiled
code works fine in AXD. It starts executing from location 0x8000 like it
should, prints to the console and exits properly.
The code genrated by GCC is very different. When i open the binary in AXD i
get a warning 'Code has no entry point'. It attempts to start executing from
0x0000 and the assembly looks very odd.
This is what the CodeWorrier binary looks like in AXD :
__main [0xe28f8090] add r8,pc,#0x90 ; #0x8098
00008004 [0xe898000f] ldmia r8,{r0-r3}
00008008 [0xe0800008] add r0,r0,r8
0000800c [0xe0811008] add r1,r1,r8
00008010 [0xe0822008] add r2,r2,r8
00008014 [0xe0833008] add r3,r3,r8
00008018 [0xe240b001] sub r11,r0,#1
0000801c [0xe242c001] sub r12,r2,#1
_move_region [0xe1500001] cmp r0,r1
00008024 [0x0a00000e] beq _zero_region
00008028 [0xe8b00070] ldmia r0!,{r4-r6}
0000802c [0xe1540005] cmp r4,r5
00008030 [0x0afffffa] beq _move_region
00008034 [0xe3140001] tst r4,#1
00008038 [0x1084400b] addne r4,r4,r11
0000803c [0xe3150001] tst r5,#1
00008040 [0x1085500b] addne r5,r5,r11
00008044 [0xe3150002] tst r5,#2
00008048 [0x10855009] addne r5,r5,r9
0000804c [0xe3c55003] bic r5,r5,#3
_move_loop [0xe2566004] subs r6,r6,#4
00008054 [0x24947004] ldrcs r7,[r4],#4
00008058 [0x24857004] strcs r7,[r5],#4
0000805c [0x8afffffb] bhi _move_loop
00008060 [0xeaffffee] b _move_region
_zero_region [0xe1520003] cmp r2,r3
00008068 [0x0b00038f] bleq __rt_entry
0000806c [0xe3a07000] mov r7,#0
00008070 [0xe8b20030] ldmia r2!,{r4,r5}
00008074 [0xe3140001] tst r4,#1
00008078 [0x1084400c] addne r4,r4,r12
And this is what the GCC binary looks like :
00000000 [0xe59ffa38] ldr pc,0x00000a40 ; = #0x00000b80
00000004 [0xe59ffa38] ldr pc,0x00000a44 ; = #0x00000b90
00000008 [0xe59ffa38] ldr pc,0x00000a48 ; = #0x00000ba0
0000000c [0xe59ffa38] ldr pc,0x00000a4c ; = #0x00000bb0
00000010 [0xe59ffa38] ldr pc,0x00000a50 ; = #0x00000bc0
00000014 [0xe59ffa38] ldr pc,0x00000a54 ; = #0x00000bd0
00000018 [0xe59ffa38] ldr pc,0x00000a58 ; = #0x00000be0
0000001c [0xe59ffa38] ldr pc,0x00000a5c ; = #0x00000bf0
00000020 [0xe7ff0010] dci 0xe7ff0010 ; ? undefined
00000024 [0xe800e800] stmda r0,{r11,r13-pc}
00000028 [0xe7ff0010] dci 0xe7ff0010 ; ? undefined
0000002c [0xe800e800] stmda r0,{r11,r13-pc}
00000030 [0xe7ff0010] dci 0xe7ff0010 ; ? undefined
00000034 [0xe800e800] stmda r0,{r11,r13-pc}
00000038 [0xe7ff0010] dci 0xe7ff0010 ; ? undefined
0000003c [0xe800e800] stmda r0,{r11,r13-pc}
00000040 [0xe7ff0010] dci 0xe7ff0010 ; ? undefined
00000044 [0xe800e800] stmda r0,{r11,r13-pc}
00000048 [0xe7ff0010] dci 0xe7ff0010 ; ? undefined
0000004c [0xe800e800] stmda r0,{r11,r13-pc}
00000050 [0xe7ff0010] dci 0xe7ff0010 ; ? undefined
00000054 [0xe800e800] stmda r0,{r11,r13-pc}
This code doesn't seem to do anything intelligeble. Even if i scroll down to
location 0x8000 the same two instructions (stmda and dci) are still being
repeated.
The binary generated by GCC is a relacatable ELF right? So does it need to
be converted in some way so that it will be located to start at 0x8000?
Any help will be very welcome.
Gareth
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