[fpc-devel] I could use some help on gdb problems with pic32 (missing debuginfo)

[Michael Ring]

Hi!

I have spent a while trying to figure out what I am doing wrong but I do 
not have clue. I can compile a binary for pic32 just fine
but when I load it into gdb I get an error: Dwarf Error: bad length 
(0x6f590000) in compilation unit header (offset 0x7e + 0)

when I look at the file with readelf then I can see that there are 
symbols in the file.

what is strange is that nm does show wrong addresses (but this seems to 
be a known issue for mips, the 32bit addresses somehow get incorrectly 
converted to 64 bits (i tried -msym32 for as, this did not help). I 
needed to apply a patch for ihex.c in binutils-2.23.2, without this I 
could not create .hex files because of this problem. I also compiled 
binutils from ChipKit pic32, there the fix seems to be included, the 
addresses are wrong there, too.

I also tried binutils from xc32 compiler, they show the addresses 
correctly but the linker seems to be somewhat incompatible, i get the 
following error:
/Applications/microchip/xc32/v1.21/bin/xc32-ld -g -EL --gc-sections  -L. 
-o hello.elf -T link.res
xc32-ld: Link Error: invalid attributes for section 
'.text.b_DEBUGSTART_$P$HELLO'


So right now I am a little out of ideas on how to continue. Florian has 
created a subversion account for me so I can check in the whole 
pic32code in case somebody has some spare time to help me, I wanted to 
do this the moment I can debug a program on a pic, seems I have to do 
this a little earlier.....


Here's a link to the created binary, in case this helps:

http://temp.michael-ring.org/hello.elf


Michael

--- here are some outputs for your reference

ppcrossmipsel -MObjFPC -Scghi -Ch1024 -Cs1024 -Tembedded -Pmipsel -gw2 
-vewnhix -l -Cpmips32r2 -WpPIC32MX220F032C -XPpic32mx-elf32 
-FD/usr/local/bin -a -godwarfsets -godwarfmethodclassprefix hello.pas
***** /usr/local/bin/pic32mx-elf32-as -mabi=eabi -march=mips32r2 
-mtune=mips32r2 -W -EL  -msym32 -o hello.o hello.s
***** /usr/local/bin/pic32mx-elf32-ld -g -EL    --gc-sections  -L. -o 
hello.elf -T link.res

mips-sde-elf-gdb hello.elf
Reading symbols from /Users/ring/devel/hello/hello.elf...Dwarf Error: 
bad length (0x6f590000) in compilation unit header (offset 0x7e + 0) [in 
module /Users/ring/devel/hello/hello.elf]
(no debugging symbols found)...done.

Section Headers:
   [Nr] Name              Type            Addr     Off    Size   ES Flg 
Lk Inf Al
   [ 0]                   NULL            00000000 000000 000000 00      
0   0  0
   [ 1] .reset            PROGBITS        bfc00000 030000 000118 00 AX  
0   0  4
   [ 2] .bev_excpt        PROGBITS        bfc00380 030380 000010 00 AX  
0   0  4
   [ 3] .text             PROGBITS        9d000000 010000 000970 00 AX  
0   0  4
   [ 4] .data             PROGBITS        a0000000 020000 000064 00 WA  
0   0  4
   [ 5] .got              PROGBITS        a0000070 020070 0000b4 04 WAp  
0   0 16
   [ 6] .bss              NOBITS          a0000124 020124 00000a 00 WA  
0   0  4
   [ 7] .reginfo          MIPS_REGINFO    00000000 030390 000018 18      
0   0  4
   [ 8] .debug_line       MIPS_DWARF      00000000 0303a8 0119c4 00      
0   0  4
   [ 9] .debug_abbrev     MIPS_DWARF      00000000 041d6c 0003a7 00      
0   0  1
   [10] .debug_info       MIPS_DWARF      00000000 042114 047ee4 00      
0   0  4
   [11] .shstrtab         STRTAB          00000000 089ff8 000072 00      
0   0  1
   [12] .symtab           SYMTAB          00000000 08a29c 018100 10     
13 5206  4
   [13] .strtab           STRTAB          00000000 0a239c 0268f4 00      
0   0  1

Program Headers:
   Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
   LOAD           0x010000 0x9d000000 0x9d000000 0x00970 0x00970 R E 0x10000
   LOAD           0x020000 0xa0000000 0x9d000970 0x00064 0x00064 RW 0x10000
   LOAD           0x020070 0xa0000070 0x9d0009d4 0x000b4 0x000b4 RW 0x10000
   LOAD           0x020124 0xa0000124 0xa0000124 0x00000 0x0000a RW 0x10000
   LOAD           0x030000 0xbfc00000 0xbfc00000 0x00390 0x00390 R E 0x10000

  Section to Segment mapping:
   Segment Sections...
    00     .text
    01     .data
    02     .got
    03     .bss
    04     .reset .bev_excpt

There is no dynamic section in this file.
There are no relocations in this file.
There are no unwind sections in this file.
Symbol table '.symtab' contains 6160 entries:

pic32mx-elf32-nm -n hello.elf
...
ffffffffbfc00000 A _RESET_ADDR
ffffffffbfc00000 T _reset
ffffffffbfc00010 T _startup

mips-sde-elf-objdump -x hello.o
   7 .text.b_DEBUGSTART_$P$HELLO 00000000  00000000  00000000 000000e8  2**0
                   CONTENTS, ALLOC, LOAD, CODE
   8 .text.n_main  0000003c  00000000  00000000  000000e8  2**2
                   CONTENTS, ALLOC, LOAD, RELOC, CODE