Using gdbserver to debug MDM9xxx

openembedded提供了一個良好的gdb環境，設定步驟如下。

brook@vista:/home/brook/apps_proc/poky/build$ tar zxvf tmp-glibc/deploy/images/mdm9607/machine-image-mdm9607-dbg.tar.gz
./
./var/
./var/lib/
./var/lib/opkg/
./var/lib/opkg/info/
...

brook@vista:/home/brook/apps_proc/poky/build$ mv usr/lib/.debug/* usr/lib/
brook@vista:/home/brook/apps_proc/poky/build$ mv lib/.debug/* lib

brook@vista:/home/brook/apps_proc/poky/build$ ln -s libconfig.so.9.2.0 usr/lib/libconfig.so.9
...

brook@vista:/home/brook/apps_proc/poky/build$ ln -s libpthread-2.22.so lib/libpthread.so.0
brook@vista:/home/brook/apps_proc/poky/build$ ln -s librt-2.22.so lib/librt.so.1
brook@vista:/home/brook/apps_proc/poky/build$ ln -s libm-2.22.so lib/libm.so.6
brook@vista:/home/brook/apps_proc/poky/build$ ln -s libc-2.22.so lib/libc.so.6
brook@vista:/home/brook/apps_proc/poky/build$ ln -s ld-2.22.so lib/ld-linux.so.3
brook@vista:/home/brook/apps_proc/poky/build$ ln -s libdl-2.22.so lib/libdl.so.2
...

brook@vista:/home/brook/apps_proc/poky/build/tmp-glibc/work/armv7a-vfp-neon-oe-linux-gnueabi/myprog/git-r0/build/src$ adb push myprog /usr/bin/myprog

brook@vista:/home/brook/apps_proc/poky/build/tmp-glibc/work/armv7a-vfp-neon-oe-linux-gnueabi/myprog/git-r0/build/src$ adb shell
sh-3.2# gdbserver :2345 /usr/bin/myprog
Process /usr/bin/myprog created; pid = 9035
Listening on port 2345

接著host端就可以開啟GDB來debug了

brook@vista:/home/brook/apps_proc/poky/build/tmp-glibc/work/armv7a-vfp-neon-oe-linux-gnueabi/myprog/git-r0/build/src$ arm-oe-linux-gnueabi-gdb myprog 
GNU gdb (GDB) 7.10.1
Copyright (C) 2015 Free Software Foundation, Inc.
...
Reading symbols from myprog...done.
(gdb) set sysroot /home/brook/apps_proc/poky/build/
(gdb) target remote 10.0.0.1:2345
Remote debugging using 10.0.0.1:2345
Reading symbols from /home/brook/apps_proc/poky/build//lib/ld-linux.so.3...done.
0xb6fceac0 in ?? ()
(gdb) b main
Breakpoint 1 at 0x7f5595ac: file /home/brook/apps_proc/poky/build/tmp-glibc/work/armv7a-vfp-neon-oe-linux-gnueabi/myprog/git-r0/src/main.c, line 207.
(gdb) c
Continuing.

Breakpoint 1, main (argc=1, argv=0xbefffdf4)
    at /home/brook/apps_proc/poky/build/tmp-glibc/work/armv7a-vfp-neon-oe-linux-gnueabi/myprog/git-r0/src/main.c:207
207     {
(gdb) set sysroot /home/brook/apps_proc/poky/build
warning: .dynamic section for "/home/brook/apps_proc/poky/build/lib/libpthread.so.0" is not at the expected address (wrong library or version mismatch?)
warning: .dynamic section for "/home/brook/apps_proc/poky/build/lib/libm.so.6" is not at the expected address (wrong library or version mismatch?)
warning: .dynamic section for "/home/brook/apps_proc/poky/build/lib/libc.so.6" is not at the expected address (wrong library or version mismatch?)
Use the "info sharedlibrary" command to see the complete listing.
Do you need "set solib-search-path" or "set sysroot"?
Reading symbols from /home/brook/apps_proc/poky/build/usr/lib/libconfig.so.9...done.
Reading symbols from /home/brook/apps_proc/poky/build/lib/libpthread.so.0...done.
Reading symbols from /home/brook/apps_proc/poky/build/lib/librt.so.1...done.
Reading symbols from /home/brook/apps_proc/poky/build/lib/libm.so.6...done.
Reading symbols from /home/brook/apps_proc/poky/build/lib/libc.so.6...done.
Reading symbols from /home/brook/apps_proc/poky/build/lib/libdl.so.2...done.
(gdb) info share
From        To          Syms Read   Shared Object Library
0x7473e7c0  0x7475a328  Yes         /home/brook/apps_proc/poky/build/lib/ld-linux.so.3
0xb6fc42d0  0xb6fca6e0  Yes         /home/brook/apps_proc/poky/build/usr/lib/libconfig.so.9
0xb6ebc210  0xb6ecb4e8  Yes         /home/brook/apps_proc/poky/build/lib/libpthread.so.0
0xb6ea2720  0xb6ea6034  Yes         /home/brook/apps_proc/poky/build/lib/librt.so.1
0xb6e28bf0  0xb6e5ac20  Yes         /home/brook/apps_proc/poky/build/lib/libm.so.6
0xb6ced280  0xb6dee638  Yes         /home/brook/apps_proc/poky/build/lib/libc.so.6
0xb6cc3928  0xb6cc4870  Yes         /home/brook/apps_proc/poky/build/lib/libdl.so.2

確認所有symbol都有找到之後, 就可以開始debug之旅了.