GNU 工程調試器（GDB）是一個常用的 Unix 調試器。本文詳述使用 gdb 調試 Android 應用和進程的方法。
調試運行中的應用或進程
gdbclient 是源碼庫中的一個 shell 腳本調試工具，它位於 android-7.1.1_r22/development/scripts/gdbclient。該腳本將根據 Android 源碼庫的根目錄，設置端口轉發，在設備上啓動適當的 gdbserver，在主機上啓動適當的 gdb，配置 gdb 查找符號，並將 gdb 連接到遠程的 gdbserver。
在執行 gdbclient 首先需要設置 ANDROID_BUILD_TOP 環境變量，這個環境變量可以手動設置，如：
/media/data/Androids/android-7.1.1_r22$ export ANDROID_BUILD_TOP=/media/data/Androids/android-7.1.1_r22
也可以通過如下命令設置：
/media/data/Androids/android-7.1.1_r22$ source build/envsetup.sh
including device/asus/fugu/vendorsetup.sh
including device/generic/mini-emulator-arm64/vendorsetup.sh
including device/generic/mini-emulator-armv7-a-neon/vendorsetup.sh
including device/generic/mini-emulator-mips64/vendorsetup.sh
including device/generic/mini-emulator-mips/vendorsetup.sh
including device/generic/mini-emulator-x86_64/vendorsetup.sh
including device/generic/mini-emulator-x86/vendorsetup.sh
including device/google/dragon/vendorsetup.sh
including device/google/marlin/vendorsetup.sh
including device/htc/flounder/vendorsetup.sh
including device/huawei/angler/vendorsetup.sh
including device/lge/bullhead/vendorsetup.sh
including device/linaro/hikey/vendorsetup.sh
including device/moto/shamu/vendorsetup.sh
including sdk/bash_completion/adb.bash
hanpfei0306@ThundeRobot:/media/data/Androids/android-7.1.1_r22$ lunch 18
============================================
PLATFORM_VERSION_CODENAME=REL
PLATFORM_VERSION=7.1.1
TARGET_PRODUCT=aosp_sailfish
TARGET_BUILD_VARIANT=userdebug
TARGET_BUILD_TYPE=release
TARGET_BUILD_APPS=
TARGET_ARCH=arm64
TARGET_ARCH_VARIANT=armv8-a
TARGET_CPU_VARIANT=generic
TARGET_2ND_ARCH=arm
TARGET_2ND_ARCH_VARIANT=armv7-a-neon
TARGET_2ND_CPU_VARIANT=krait
HOST_ARCH=x86_64
HOST_2ND_ARCH=x86
HOST_OS=linux
HOST_OS_EXTRA=Linux-4.4.0-89-generic-x86_64-with-Ubuntu-16.04-xenial
HOST_CROSS_OS=windows
HOST_CROSS_ARCH=x86
HOST_CROSS_2ND_ARCH=x86_64
HOST_BUILD_TYPE=release
BUILD_ID=NMF26X
OUT_DIR=out
============================================
也就是 Android 源碼庫編譯前配置。
如果沒有設置 ANDROID_BUILD_TOP 環境變量的話，在執行 gdbclient 時將報出如下的錯誤：
/media/data/Androids/android-7.1.1_r22$ development/scripts/gdbclient
$ANDROID_BUILD_TOP is not set. Source build/envsetup.sh.
有了前面的那些配置，即可使用 gdbclient 調試 Android 應用程序了。要連接一個已經在運行的應用或本地層守護進程，則以 PID 作爲參數執行 gdbclient。比如，要調試 PID 爲 1234 的進程，則運行：
$ gdbclient 1234
它會爲我們準備一切。
調試本地進程啓動
要調試進程的啓動，則使用 gdbserver 或 gdbserver64 （64 位進程）。比如：
$ adb shell gdbserver64 :5039 /system/bin/screenrecord
示例輸出如下：
Process /system/bin/screenrecord created; pid = 12571
Listening on port 5039
接着，從 gdbserver 的輸出中得到應用程序的 PID，並在另一個終端窗口中使用如下命令：
$ gdbclient 12571
最後，在 gdb 提示符下鍵入 continue。
使用的 gdbserver 與實際運行的應用程序格式不匹配時，在執行 gdbclient 時將報出如下的錯誤：
$ gdbclient 12484
including device/asus/fugu/vendorsetup.sh
including device/generic/mini-emulator-arm64/vendorsetup.sh
including device/generic/mini-emulator-armv7-a-neon/vendorsetup.sh
including device/generic/mini-emulator-mips64/vendorsetup.sh
including device/generic/mini-emulator-mips/vendorsetup.sh
including device/generic/mini-emulator-x86_64/vendorsetup.sh
including device/generic/mini-emulator-x86/vendorsetup.sh
including device/google/dragon/vendorsetup.sh
including device/google/marlin/vendorsetup.sh
including device/htc/flounder/vendorsetup.sh
including device/huawei/angler/vendorsetup.sh
including device/lge/bullhead/vendorsetup.sh
including device/linaro/hikey/vendorsetup.sh
including device/moto/shamu/vendorsetup.sh
including sdk/bash_completion/adb.bash
It looks like gdbserver is already attached to 12484 (process is traced), trying to connect to it using local port=5039
GNU gdb (GDB) 7.11
Copyright (C) 2016 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 "x86_64-linux-gnu".
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 out/target/product/sailfish/symbols/system/bin/screenrecord...done.
warning: Selected architecture aarch64 is not compatible with reported target architecture arm
out/target/product/sailfish/gdbclient.cmds:4: Error in sourced command file:
Reply contains invalid hex digit 59
(gdb) break main
Breakpoint 1 at 0x5820: file frameworks/av/cmds/screenrecord/screenrecord.cpp, line 900.
(gdb) r
Starting program: /media/data/Androids/android-7.1.1_r22/out/target/product/sailfish/symbols/system/bin/screenrecord
/usr/local/google/buildbot/src/android/master-ndk/toolchain/gdb/gdb-7.11/gdb/regcache.c:1056: internal-error: regcache_raw_supply: Assertion `regnum >= 0 && regnum < regcache->descr->nr_raw_registers' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n) y
This is a bug, please report it. For instructions, see:
<http://www.gnu.org/software/gdb/bugs/>.
/usr/local/google/buildbot/src/android/master-ndk/toolchain/gdb/gdb-7.11/gdb/regcache.c:1056: internal-error: regcache_raw_supply: Assertion `regnum >= 0 && regnum < regcache->descr->nr_raw_registers' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Create a core file of GDB? (y or n) y
/media/data/Androids/android-7.1.1_r22/prebuilts/gdb/linux-x86/bin/gdb: 行 3: 12882 已放棄 (核心已轉儲) PYTHONHOME="$GDBDIR/.." "$GDBDIR/gdb-orig" "$@"
hanpfei0306@ThundeRobot:/media/data/Androids/android-7.1.1_r22$ /bin/bash: /media/data/Androids/android-7.1.1_r22/out/target/product/sailfish/symbols/system/bin/screenrecord: cannot execute binary file: 可執行文件格式錯誤
/bin/bash: /media/data/Androids/android-7.1.1_r22/out/target/product/sailfish/symbols/system/bin/screenrecord: 成功
即我們在 gdb 的提示符下輸入 continue 執行應用程序之後，報出了 可執行文件格式錯誤。
Done.