Re: GDB can not read debug symbols

[Orlando Arias <oarias at knights dot ucf dot edu>]

Greetings,

As asked in IRC, here is some more debug information obtained from GDB
as the file is opened, a connection to the remote stub is established, a
breakpoint is set, execution is triggered and stepping inside main() is
attempted. These logs are provided as an attachment. I am not entirely
sure what I am looking at here, but it seems that GDB is not populating
line numbers for some of the compilation units, although the data is
available.

Any help would be appreciated. Thank you.

Cheers,
Orlando.

On 09/29/2015 05:36 PM, Orlando Arias wrote:
> Greetings,
> 
> I am experimenting with the msp430-elf port of gdb (7.10) and it seems
> it is not reading debugging symbols gcc (5.2.0) is issuing.
> 
> The test program is:
> 
> #include <msp430.h>
> 
> __attribute__((noreturn)) void main() {
> 	WDTCTL = WDTPW | WDTHOLD;
> 	P1DIR = 0xff;
> 	P1OUT = 0xff;
> 	while(1) {
> 		__delay_cycles(2500000);
> 		P1OUT ^= 0xff;
> 	}
> }
> 
> And it is compiled with:
> 
> $msp430-elf-gcc -g -O0 -mmcu=msp430f2013 test.c -o test.elf
> 
> readelf reports:
> 
> CU: ./test.c:
> File name                            Line number    Starting address
> hello.c                                        5              0xf924
> hello.c                                        6              0xf924
> 
> hello.c                                        7              0xf92a
> 
> hello.c                                        8              0xf92e
> 
> hello.c                                       12              0xf932
> 
> hello.c                                       13              0xf94e
> 
> hello.c                                       14              0xf95c
> 
> 
> When testing the program on hardware through mspdebug
> 
> $ msp430-elf-gdb ./test.elf
> GNU gdb (GDB) 7.10
> Copyright (C) 2015 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later
> <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
> and "show warranty" for details.
> This GDB was configured as "--host=x86_64-unknown-linux-gnu
> --target=msp430-elf".
> Type "show configuration" for configuration details.
> For bug reporting instructions, please see:
> <http://www.gnu.org/software/gdb/bugs/>.
> Find the GDB manual and other documentation resources online at:
> <http://www.gnu.org/software/gdb/documentation/>.
> For help, type "help".
> Type "apropos word" to search for commands related to "word"...
> Reading symbols from ./test.elf...done.
> (gdb) target remote :1234
> (gdb) break main
> Breakpoint 1 at 0xf924
> (gdb) cont
> Continuing.
> 
> Breakpoint 1, 0x0000f924 in main ()
> (gdb) step
> Single stepping until exit from function main,
> which has no line number information.
> 
> At this point, gdb singlesteps forever, unable to trace through the
> program. However, if compiling the program using
> 
> $ msp430-elf-gcc -gstabs -O0 -mmcu=msp430f2013 test.c -o test.elf
> 
> readelf no longer reports any line number information, but GDB works as
> intended. Attached is the linker script being used. Thank you.
> 
> Cheers,
> Orlando.
>

Attachment: gdb_readelf_dump
Description: Text document

Attachment: signature.asc
Description: OpenPGP digital signature