VanFanel
Apprentice
Joined: 19 Feb 2007
Posts: 161
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 Posted: Sun Aug 12, 2012 1:24 pm Post subject: GDB on Pandaboard: can't single-step code (next) |
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Hi there,
I'm having a very hard time trying to get GDB working right on my Pandaboard (an ARM based SBC, see www.pandaboard.org). It won't allow me to single-step thru with code with "next" as I usually do in my X86 pc.
It happens in shared library code I'm debugging (SDL_fbevents.c).
Both the program using the library and the library itself are compiled with the gcc CFLAGS and CXXFLAGS "-g -O0", so they contain degub symbols and they should be pretty much un-optimized.
I can place a bp and it does stop where I want, but after I ussie a "next" or two gdb goes wild and runs the rest of the program without my control.
Here's a typical gdb session. I end the program manually after the strange "jump" takes place and kicks me out of the function I'd like to single-step.
| Code: |
manuel@panda ~/parallax-2 $ gdb parallax2
GNU gdb (Gentoo 7.4.1 p2) 7.4.1
Copyright (C) 2012 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 "armv7a-hardfloat-linux-gnueabi".
For bug reporting instructions, please see:
<http://bugs.gentoo.org/>...
Reading symbols from /home/manuel/parallax-2/parallax2...done.
(gdb) b SDL_fbevents.c : 248
No source file named SDL_fbevents.c.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 1 (SDL_fbevents.c : 248) pending.
(gdb) r
Starting program: /home/manuel/parallax-2/parallax2
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/libthread_db.so.1".
Breakpoint 1, KMS_OpenKeyboard (this=0x13008) at ./src/video/kms/SDL_fbevents.c:248
248 if ( keyboard_fd < 0 ) {
(gdb) n
254 tty0_fd = -1;
(gdb) n
255 for ( i=0; tty0[i] && (tty0_fd < 0); ++i ) {
(gdb) n
KMS_VideoInit (this=0x13008, vformat=0xbefff330) at ./src/video/kms/SDL_fbvideo.c:465
465 KMS_VideoQuit(this);
(gdb) bt
#0 KMS_VideoInit (this=0x13008, vformat=0xbefff330) at ./src/video/kms/SDL_fbvideo.c:465
#1 0xb6f8eecc in SDL_VideoInit (driver_name=0x0, flags=0) at ./src/video/SDL_video.c:249
#2 0xb6f4f3ec in SDL_InitSubSystem (flags=32) at ./src/SDL.c:89
#3 0xb6f4f584 in SDL_Init (flags=32) at ./src/SDL.c:162
#4 0x00008984 in main (argc=1, argv=0xbefff574) at parallax2.c:187
(gdb) q
A debugging session is active.
Inferior 1 [process 1369] will be killed.
Quit anyway? (y or n) y
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Here's the full SDL_fbevents.c, so you can look what GDB is ignoring and jumping over. Go to line 248 to see where I placed my bp to start the single-stepping:
http://svn.libsdl.org/tags/SDL/merges/trunk-1.3-3/src/video/fbcon/SDL_fbevents.c
The library is not stripped:
| Code: |
manuel@panda ~/parallax-2 $ file /usr/lib/libSDL-1.2.so.0.11.4
/usr/lib/libSDL-1.2.so.0.11.4: ELF 32-bit LSB shared object, ARM, verscally linked, not stripped
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...and, as I said, it's compiled with "-d -O0". I got sure every gcc command in the make process had the "-g -O0" parameters.
The code lines seem to be contiguous, here's how objdump -dl on /usr/lib/libSDL-1.2.so.0.11.4 looks around the line I start my single-stepping on (SDL_fbevents.c:248):
| Code: |
manuel@panda ~/parallax-2 $ objdump -dl /usr/lib/libSDL-1.2.so.0.11.4 |grep -50 SDL_events.c:248
ffa0: e08f3003 add r3, pc, r3
ffa4: e3a02000 mov r2, #0
ffa8: e5832000 str r2, [r3]
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:234
ffac: ebffffdb bl ff20 <SDL_StopEventLoop>
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:237
ffb0: e59f3100 ldr r3, [pc, #256] ; 100b8 <SDL_StartEventLoop+0x13c>
ffb4: e08f3003 add r3, pc, r3
ffb8: e3a02000 mov r2, #0
ffbc: e5832000 str r2, [r3]
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:238
ffc0: e59f30f4 ldr r3, [pc, #244] ; 100bc <SDL_StartEventLoop+0x140>
ffc4: e08f3003 add r3, pc, r3
ffc8: e1a00003 mov r0, r3
ffcc: e3a01001 mov r1, #1
ffd0: e3a02020 mov r2, #32
ffd4: ebffd2b7 bl 4ab8 <_init+0x284>
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:239
ffd8: e59f30e0 ldr r3, [pc, #224] ; 100c0 <SDL_StartEventLoop+0x144>
ffdc: e08f3003 add r3, pc, r3
ffe0: e3e02000 mvn r2, #0
ffe4: e5832000 str r2, [r3]
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:241
ffe8: e59f30d4 ldr r3, [pc, #212] ; 100c4 <SDL_StartEventLoop+0x148>
ffec: e08f3003 add r3, pc, r3
fff0: e5933000 ldr r3, [r3]
fff4: e3c32a02 bic r2, r3, #8192 ; 0x2000
fff8: e59f30c8 ldr r3, [pc, #200] ; 100c8 <SDL_StartEventLoop+0x14c>
fffc: e08f3003 add r3, pc, r3
10000: e5832000 str r2, [r3]
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:242
10004: e59f30c0 ldr r3, [pc, #192] ; 100cc <SDL_StartEventLoop+0x150>
10008: e08f3003 add r3, pc, r3
1000c: e3a02000 mov r2, #0
10010: e5c3200d strb r2, [r3, #13]
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:245
10014: e3a03000 mov r3, #0
10018: e50b3008 str r3, [fp, #-8]
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:246
1001c: ebfffe0a bl f84c <SDL_AppActiveInit>
10020: e1a03000 mov r3, r0
10024: e51b2008 ldr r2, [fp, #-8]
10028: e0823003 add r3, r2, r3
1002c: e50b3008 str r3, [fp, #-8]
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:247
10030: eb000330 bl 10cf8 <SDL_KeyboardInit>
10034: e1a03000 mov r3, r0
10038: e51b2008 ldr r2, [fp, #-8]
1003c: e0823003 add r3, r2, r3
10040: e50b3008 str r3, [fp, #-8]
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:248
10044: eb000c97 bl 132a8 <SDL_MouseInit>
10048: e1a03000 mov r3, r0
1004c: e51b2008 ldr r2, [fp, #-8]
10050: e0823003 add r3, r2, r3
10054: e50b3008 str r3, [fp, #-8]
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:249
10058: eb000f76 bl 13e38 <SDL_QuitInit>
1005c: e1a03000 mov r3, r0
10060: e51b2008 ldr r2, [fp, #-8]
10064: e0823003 add r3, r2, r3
10068: e50b3008 str r3, [fp, #-8]
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:250
1006c: e51b3008 ldr r3, [fp, #-8]
10070: e3530000 cmp r3, #0
10074: aa000001 bge 10080 <SDL_StartEventLoop+0x104>
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:252
10078: e3e03000 mvn r3, #0
1007c: ea000008 b 100a4 <SDL_StartEventLoop+0x128>
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:256
10080: e51b0010 ldr r0, [fp, #-16]
10084: ebffff13 bl fcd8 <SDL_StartEventThread>
10088: e1a03000 mov r3, r0
1008c: e3530000 cmp r3, #0
10090: aa000002 bge 100a0 <SDL_StartEventLoop+0x124>
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:257
10094: ebffffa1 bl ff20 <SDL_StopEventLoop>
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:258
10098: e3e03000 mvn r3, #0
1009c: ea000000 b 100a4 <SDL_StartEventLoop+0x128>
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:260
100a0: e3a03000 mov r3, #0
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:261
100a4: e1a00003 mov r0, r3
100a8: e24bd004 sub sp, fp, #4
100ac: e8bd8800 pop {fp, pc}
100b0: 0005aa64 .word 0x0005aa64
100b4: 00059c38 .word 0x00059c38
100b8: 00059c1c .word 0x00059c1c
100bc: 0007d8ac .word 0x0007d8ac
100c0: 00059bf8 .word 0x00059bf8
100c4: 00059be8 .word 0x00059be8
100c8: 00059bd8 .word 0x00059bd8
100cc: 0007d868 .word 0x0007d868
000100d0 <SDL_AddEvent>:
SDL_AddEvent():
/home/manuel/SDL-1.2.15/./src/events/SDL_events.c:266
100d0: e92d0810 push {r4, fp}
100d4: e28db004 add fp, sp, #4
100d8: e24dd018 sub sp, sp, #24
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It's worth mentioning that I can single-step all right in this same code with the same compilation process on my Lubuntu 12.04 machine (X86_64). So there must be something Gentoo (or ARM) related causing this strange behaviour.
Here are the versions of GCC and GDB I'm using:
[code]
GNU gdb (Gentoo 7.4.1 p2) 7.4.1
This GDB was configured as "armv7a-hardfloat-linux-gnueabi".
[code]
[code]
manuel@panda ~/parallax-2 $ gcc -v
Using built-in specs.
COLLECT_GCC=/usr/armv7a-hardfloat-linux-gnueabi/gcc-bin/4.6.3/gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/armv7a-hardfloat-linux-gnueabi/4.6.3/lto-wrapper
Target: armv7a-hardfloat-linux-gnueabi
Configured with: /var/tmp/portage/sys-devel/gcc-4.6.3/work/gcc-4.6.3/configure --prefix=/usr --bindir=/usr/armv7a-hardfloat-linux-gnueabi/gcc-bin/4.6.3 --includedir=/usr/lib/gcc/armv7a-hardfloat-linux-gnueabi/4.6.3/include --datadir=/usr/share/gcc-data/armv7a-hardfloat-linux-gnueabi/4.6.3 --mandir=/usr/share/gcc-data/armv7a-hardfloat-linux-gnueabi/4.6.3/man --infodir=/usr/share/gcc-data/armv7a-hardfloat-linux-gnueabi/4.6.3/info --with-gxx-include-dir=/usr/lib/gcc/armv7a-hardfloat-linux-gnueabi/4.6.3/include/g++-v4 --host=armv7a-hardfloat-linux-gnueabi --build=armv7a-hardfloat-linux-gnueabi --disable-altivec --disable-fixed-point --without-ppl --without-cloog --enable-lto --with-float=hard --disable-nls --with-system-zlib --enable-obsolete --disable-werror --enable-secureplt --disable-multilib --enable-libmudflap --disable-libssp --enable-libgomp --with-python-dir=/share/gcc-data/armv7a-hardfloat-linux-gnueabi/4.6.3/python --enable-checking=release --disable-libgcj --with-arch=armv7-a --with-float=hard --with-fpu=vfpv3-d16 --enable-languages=c,c++,fortran --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu --with-bugurl=https://bugs.gentoo.org/ --with-pkgversion='Gentoo 4.6.3 p1.5, pie-0.5.2'
Thread model: posix
gcc version 4.6.3 (Gentoo 4.6.3 p1.5, pie-0.5.2)
[/code]
thanks for taking the time looking at my post for help. |
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