使用gdbserver远程调试
使用gdbserver遠程調試 
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1.默認crosstool交叉編譯器沒有自帶gdbserver,需要自行編譯 
到GNU官方FTP下載,目前最新版的是gdb-6.7.1
下載地址:http://ftp.gnu.org/gnu/gdb/ 
注:若已有gdbserver,可以直接跳到步驟4 
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2.編譯gdbserver
編譯GDB源碼時只需要編譯出gdbserver就可以了,交叉編譯器自帶arm-linux-gdb(client端)可以使用。
gdb-6.7.1
# cd gdb-6.7.1/gdb/gdbserver/
#./configure --host=arm-linux --prefix=/work/install/gdbserver
#make
#make install 
這時會在/work/install/gdbserver目錄下生成bin/gdbserver,將其拷貝到nfs文件系統
#cd /work/install/gdbserver
#cp bin/gdbserver /work/nfs/rootfs/bin 
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3.庫問題
這里需要注意的是運行gdbserver還需要libthread_db庫,若你自己做的文件系統內沒有這個庫的話需要從交叉編譯器內拷一個過去。
# gdbserver -h (target)
gdbserver: error while loading shared libraries: libthread_db.so.1: cannot open shared object file: No such file or directory
# cp -avf lib/libthread_db* /work/nfs/rootfs_bluetooth_omap/lib/
`/lib/libthread_db-1.0.so' -> `/work/nfs/rootfs/lib/libthread_db-1.0.so'
`/lib/libthread_db.so.1' -> `/work/nfs/rootfs/lib/libthread_db.so.1' 
注:若不知道缺少什么庫可以根據運行時錯誤提示拷貝或者用先用strace跟蹤一下:
#strace -f -F -o strace.log gdbserver -h
#vi strace.log? 
發現如下字段:
872?? writev(2, [{"gdbserver", 9}, {": ", 2}, {"error while loading shared libra"..., 36}, {": ", 2}, {"libthread_db.so.1", 17}, {": ", 2}, {"cannot open shared object file", 30}, {": ", 2}, {"No such file or directory", 25}, {"\n", 1}], 10) = 126
872?? exit_group(127)?????????????????? = ?
得知缺少libthread_db.so.1庫(紅色部分標出)。 
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4.調試過程
1)Target端建立遠程調試服務
# gdbserver 192.168.167.170:1234 obexftp (target)
Process obexftp created; pid = 858
Listening on port 1234 
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2)Host端GDB加載要調試的程序
這里要調試的程序得是交叉編譯過的,并且加了-g參數。不過大部分編譯程序默認就是加了-g參數的,這點可以從編譯時的log看出。
# arm-linux-gdb obexftp 
GNU gdb 6.6.50.20070301 (MontaVista 6.6.50-2.0.1.0702865 2007-03-26)
Copyright (C) 2007 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.? Type "show warranty" for details.
This GDB was configured as "--host=i686-pc-linux-gnu --target=armv5tl-montavista-linux-gnueabi"... 
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3)連接到目標板調試服務
(gdb) target remote 192.168.167.15:1234
Remote debugging using 192.168.167.15:1234
Error while reading shared library symbols:
Dwarf Error: Can't read DWARF data from '/opt/montavista/pro/devkit/arm/v5t_le/target/usr/lib/debug/lib/ld-2.5.90.so.debug' 
0x400007a0 in _start () from /opt/montavista/pro/devkit/arm/v5t_le/target/lib/ld-linux.so.3
注:上面兩行錯誤信息暫時不用管,原因還不清楚,但是暫時發現不影響使用。 
連接成功后ARM板上的信息應該是這樣的: 
# ./gdbserver 192.168.0.29:1234 arm0702_8.out 
Process arm0702_8.out created; pid = 228 
Remote debugging from host 192.168.0.29? <----多出這一行 
上面這行表示宿主機和開發板連接成功。現在我們就可以在Host端像調試本地程序一樣調試ARM板上程序。不過,需要注意的是這里執行程序要用“c”,不能用“r”。因為程序已經在Target Board上面由gdbserver啟動了。 
調試過程如下:
(gdb) b main
Breakpoint 1 at 0x9870: file obexftp.c, line 376.
(gdb) info b
Num Type?????????? Disp Enb Address??? What
1?? breakpoint???? keep y?? 0x00009870 in main at obexftp.c:376
(gdb) c
Continuing.
Error while mapping shared library sections:
/work/install/bluetooth//lib/libobexftp.so.0: No such file or directory.
Error while mapping shared library sections:
/work/install/bluetooth//lib/libc.so.6: No such file or directory. 
Breakpoint 1, main (argc=1, argv=0xbed0dec4) at obexftp.c:384
384???????????? if (strstr(argv[0], "ls") != NULL)????? most_recent_cmd = 'l';
(gdb) 
若產生這個錯誤主要是由于該調試的應用程序使用到了額外的庫,而這個庫在gdb默認的搜索路徑內沒有
(相對與遠程調試,gdb默認搜索的路徑即為交叉編譯器的庫路徑,下面我會介紹到)
因此,這里我們需要修改一下gdb默認的共享庫搜索路徑。
修改的辦法是設置GDB的環境變量:
(gdb) show solib-absolute-prefix
The current system root is "/opt/montavista/pro/devkit/arm/v5t_le/target". 
上面這個路徑即GDB默認的絕對搜索路徑,即交叉編譯器庫路徑
(gdb) show solib-search-path
The search path for loading non-absolute shared library symbol files is .
(gdb) set solib-search-path /work/install/bluetooth/lib
這個路徑為若在solib-absolute-prefix指定的路徑內沒有搜索到庫,則再繼續嘗試從該路徑進行搜索。 
這點倒有點類似于系統默認庫搜索路徑與LD_LIBRARY_PATH的關系。
詳細參考GDB手冊中相關部分:
http://wiki.chinaunix.net/index.php/GDB_Manual_15_1 
設置好solib-search-path后再運行程序:
(gdb) set solib-search-path /work/install/bluetooth/lib/
(gdb) c
Continuing.
Error while reading shared library symbols:
Dwarf Error: Can't read DWARF data from '/opt/montavista/pro/devkit/arm/v5t_le/target/usr/lib/debug/lib/ld-2.5.90.so.debug' 
Breakpoint 1, main (argc=1, argv=0xbe896eb4) at obexftp.c:384
384???????????? if (strstr(argv[0], "ls") != NULL)????? most_recent_cmd = 'l'; 
(gdb) l
379???????????? char *output_file = NULL;
380???????????? char *move_src = NULL;
381???????????? /* char *inbox; */
382
383???????????? /* preset mode of operation depending on our name */
384???????????? if (strstr(argv[0], "ls") != NULL)????? most_recent_cmd = 'l';
385???????????? if (strstr(argv[0], "get") != NULL)???? most_recent_cmd = 'g';
386???????????? if (strstr(argv[0], "put") != NULL)???? most_recent_cmd = 'p';
387???????????? if (strstr(argv[0], "rm") != NULL)????? most_recent_cmd = 'k';
388
(gdb) 
運行成功 
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注:使用GDB調試時查看代碼不是很方便。CLWEN使用VIM作為GDB前端界面,結合gdb的遠程調試功能,動態的將程序當前運行的代碼顯示在VIM上,查看起來十分方便。其遠程調試方法和GDB+GDB Server一樣,但是多了一個GUI界面(VIM)。 
轉載于:https://www.cnblogs.com/li-hao/p/3171267.html
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