本文主要是介绍Linux Kernel KDB KGDB 实体机内核调试，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
内核编译配置
CONFIG_DEBUG_INFO=y # 编译debug infoCONFIG_MAGIC_SYSRQ=y # 功能编译开关
CONFIG_MAGIC_SYSRQ_DEFAULT_ENABLE=0x1 # 默认开启项 默认存在 /proc/sysrq-trigger
CONFIG_MAGIC_SYSRQ_SERIAL=y # 串行sysrq （许多嵌入式主板都具有断开连接的 TTL 电平串行，这可能会产生一些无效的信号。导致检测到虚假sysrq ）CONFIG_KGDB=y # 需要开启 gdb 远程调试内核
CONFIG_KGDB_KDB=y # KDB调试前端
CONFIG_KDB_DEFAULT_ENABLE=0x0 # 默认不启动KDB 通过模块拔插方式开启
CONFIG_KDB_KEYBOARD=y # 需要开启 可以使用键盘
CONFIG_KDB_CONTINUE_CATASTROPHIC=0 # KDB调试内核引发的Oops等容错，=0 总是继续 =1 尝试继续 =2 强制重新启动# CONFIG_SERIAL_KGDB_NMI is not set # 此特殊驱动程序允许您临时使用 NMI 调试器端口作为普通控制台（假设该端口已连接到 KGDB）
CONFIG_HAVE_ARCH_KGDB=y # 依赖项
CONFIG_KGDB_SERIAL_CONSOLE=y # KGDB 串口调试终端配置，与 kgdb 共享串行控制台。初始化必须使用 Sysrq -g 进入
CONFIG_KGDB_TESTS=y # 这是一个 kgdb I/O 模块，专门用于测试kgdb 的内部功能。回归测试使用
# CONFIG_KGDB_TESTS_ON_BOOT is not set # 启动时进行模块内部测试
CONFIG_KGDB_LOW_LEVEL_TRAP=y # 这将为断点异常处理程序添加对 kgdb 的额外回调，这将允许 kgdb 单步执行。
内核运行时设置
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关闭随机化
grub 行添加 nokaslr注：不设置会报错 -22 Permisson denied
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kdb on conlose 设置 (对应CONFIG_KDB_DEFAULT_ENABLE=0x0)
echo ttyS0 > /sys/module/kgdboc/parameters/kgdboc # ttyS0 tty0 ttyAMA0 需要确认串口输出设备 -
开启 kdb 命令行
echo 1 > /sys/module/kdb/parameters/cmd_enable注：不设置会报错 -22 Permisson denied
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进入命令行
- 方法1：panic 自动进入
- 方法2：手动进入
echo -g > /proc/sysrq-trigger
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kdb 开机即起
grub 行添加 nokaslr kgdbwait kgdboc=ttyS0,115200n8 kdb.cmd_enable=1注：kgdb属于模块且依赖串口，cpu 初始化 调度算法初始化等流程执行已过
kdb调试
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栈 bt
[0]kdb> bt Stack traceback for pid 1092 0xffff88823568c680 1092 1080 1 2 R 0xffff88823568d9c0 bash -
所有CPU运行任务 -btc
[0]kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0-1(I), 2, 3-7(I) Stack traceback for pid 0 0xffffffff82412780 0 0 1 0 I 0xffffffff82413ac0 *swapper/0 Stack traceback for pid 0 0xffff888106e05e00 0 0 1 1 I 0xffff888106e07140 swapper/1 Stack traceback for pid 1092 0xffff88823568c680 1092 1080 1 2 R 0xffff88823568d9c0 bash Stack traceback for pid 0 0xffff888106e04680 0 0 1 3 I 0xffff888106e059c0 swapper/3 Stack traceback for pid 0 0xffff888106e2af00 0 0 1 4 I 0xffff888106e2c240 swapper/4 Stack traceback for pid 0 0xffff888106e2c680 0 0 1 5 I 0xffff888106e2d9c0 swapper/5 Stack traceback for pid 0 0xffff888106e29780 0 0 1 6 I 0xffff888106e2aac0 swapper/6 Stack traceback for pid 0 0xffff888106e28000 0 0 1 7 I 0xffff888106e29340 swapper/7 -
模块状态 lsmod
[2]kdb> lsmod Module Size modstruct Used by sunrpc 364544 0xffffffffc04d4e00 1 (Live) 0xffffffffc0488000 [ ] kvm_intel 237568 0xffffffffc052d900 0 (Live) 0xffffffffc04fb000 [ ] snd_hda_codec_generic 86016 0xffffffffc0623580 1 (Live) 0xffffffffc0611000 [ ] kvm 679936 0xffffffffc05fd100 1 (Live) 0xffffffffc056a000 [ kvm ] irqbypass 16384 0xffffffffc03bc040 1 (Live) 0xffffffffc03ba000 [ irqbypass ] crct10dif_pclmul 16384 0xffffffffc0377200 0 (Live) 0xffffffffc0375000 [ ] crc32_pclmul 16384 0xffffffffc034f200 0 (Live) 0xffffffffc034d000 [ ] qxl 73728 0xffffffffc04f76c0 1 (Live) 0xffffffffc04e8000 [ ] snd_hda_intel 45056 0xffffffffc03b7000 0 (Live) 0xffffffffc03ae000 [ ] ghash_clmulni_intel 16384 0xffffffffc00b3400 0 (Live) 0xffffffffc00b1000 [ ] snd_hda_codec 131072 0xffffffffc0482600 2 (Live) 0xffffffffc0467000 [ snd_hda_codec snd_hda_codec ] ttm 118784 0xffffffffc0427e80 1 (Live) 0xffffffffc0411000 [ ttm ] drm_kms_helper 176128 0xffffffffc0563600 1 (Live) 0xffffffffc053e000 [ drm_kms_helper ] snd_hda_core 77824 0xffffffffc0328380 3 (Live) 0xffffffffc0318000 [ snd_hda_core snd_hda_core snd_hda_core ] snd_hwdep 20480 0xffffffffc03eb080 1 (Live) 0xffffffffc03e8000 [ snd_hwdep ] syscopyarea 16384 0xffffffffc03c5000 1 (Live) 0xffffffffc03c3000 [ syscopyarea ] snd_pcm 98304 0xffffffffc03a9640 3 (Live) 0xffffffffc0395000 [ snd_pcm snd_pcm snd_pcm ] intel_rapl_perf 16384 0xffffffffc0383740 0 (Live) 0xffffffffc0381000 [ ] sysfillrect 16384 0xffffffffc037c040 1 (Live) 0xffffffffc037a000 [ sysfillrect ] sysimgblt 16384 0xffffffffc0365000 1 (Live) 0xffffffffc0363000 [ sysimgblt ] fb_sys_fops 16384 0xffffffffc035e000 1 (Live) 0xffffffffc035c000 [ fb_sys_fops ] snd_timer 32768 0xffffffffc0372100 1 (Live) 0xffffffffc036c000 [ snd_timer ] virtio_balloon 20480 0xffffffffc0355240 0 (Live) 0xffffffffc0352000 [ ] sg 40960 0xffffffffc034a0c0 0 (Live) 0xffffffffc0342000 [ ] drm 475136 0xffffffffc02f5940 4 (Live) 0xffffffffc028d000 [ drm drm drm ] snd 86016 0xffffffffc03123c0 6 (Live) 0xffffffffc0302000 [ snd snd snd snd snd snd ] psmouse 159744 0xffffffffc027bec0 0 (Live) 0xffffffffc0259000 [ ] soundcore 16384 0xffffffffc0252040 1 (Live) 0xffffffffc0250000 [ soundcore ] i2c_piix4 24576 0xffffffffc0249540 0 (Live) 0xffffffffc0245000 [ ] pcspkr 16384 0xffffffffc023f100 0 (Live) 0xffffffffc023d000 [ ] ip_tables 28672 0xffffffffc0031280 0 (Live) 0xffffffffc002c000 [ ] ext4 675840 0xffffffffc01f43c0 2 (Live) 0xffffffffc015c000 [ ] mbcache 16384 0xffffffffc0097080 1 (Live) 0xffffffffc0095000 [ mbcache ] jbd2 110592 0xffffffffc0139b00 1 (Live) 0xffffffffc0122000 [ jbd2 ] sr_mod 28672 0xffffffffc0109140 0 (Live) 0xffffffffc0104000 [ ] cdrom 57344 0xffffffffc011f280 1 (Live) 0xffffffffc0113000 [ cdrom ] sd_mod 49152 0xffffffffc01014c0 3 (Live) 0xffffffffc00f7000 [ ] ata_generic 16384 0xffffffffc006c700 0 (Live) 0xffffffffc006a000 [ ] ata_piix 36864 0xffffffffc0159240 2 (Live) 0xffffffffc0152000 [ ] crc32c_intel 24576 0xffffffffc010f200 4 (Live) 0xffffffffc010c000 [ ] libata 237568 0xffffffffc00ef9c0 2 (Live) 0xffffffffc00bc000 [ libata libata ] serio_raw 16384 0xffffffffc00ae200 0 (Live) 0xffffffffc00ac000 [ ] virtio_console 32768 0xffffffffc00a4400 0 (Live) 0xffffffffc009e000 [ ] e1000 143360 0xffffffffc0091140 0 (Live) 0xffffffffc0071000 [ ] floppy 81920 0xffffffffc0063c40 0 (Live) 0xffffffffc0055000 [ ] -
进程状态 ps
[2]kdb> ps 7 idle processes (state I) and 39 sleeping system daemon (state M) processes suppressed, use 'ps A' to see all. Task Addr Pid Parent [*] cpu State Thread Command 0xffff88823568c680 1092 1080 1 2 R 0xffff88823568d9c0 *bash0xffff888106db4680 1 0 0 0 S 0xffff888106db59c0 systemd 0xffff888106db0000 3 2 0 0 D 0xffff888106db1340 rcu_gp 0xffff888106db5e00 4 2 0 0 D 0xffff888106db7140 rcu_par_gp 0xffff888106db2f00 5 2 0 0 D 0xffff888106db4240 kworker/0:0 0xffff888106deaf00 6 2 0 0 D 0xffff888106dec240 kworker/0:0H 0xffff888106dec680 7 2 0 2 D 0xffff888106ded9c0 kworker/u16:0 0xffff888106de9780 8 2 0 0 D 0xffff888106deaac0 mm_percpu_wq 0xffff888106dede00 10 2 0 7 D 0xffff888106def140 rcu_sched 0xffff888106e01780 11 2 0 0 D 0xffff888106e02ac0 rcu_bh 0xffff888106e49780 17 2 0 1 D 0xffff888106e4aac0 kworker/1:0 0xffff888106e48000 18 2 0 1 D 0xffff888106e49340 kworker/1:0H 0xffff888106e75e00 22 2 0 2 D 0xffff888106e77140 kworker/2:0 0xffff888106e72f00 23 2 0 2 D 0xffff888106e74240 kworker/2:0H 0xffff888106e90000 27 2 0 3 D 0xffff888106e91340 kworker/3:0 0xffff888106e95e00 28 2 0 3 D 0xffff888106e97140 kworker/3:0H 0xffff888106ecaf00 32 2 0 4 D 0xffff888106ecc240 kworker/4:0 0xffff888106ecc680 33 2 0 4 D 0xffff888106ecd9c0 kworker/4:0H 0xffff888106ef0000 37 2 0 5 D 0xffff888106ef1340 kworker/5:0 0xffff888106ef5e00 38 2 0 5 D 0xffff888106ef7140 kworker/5:0H 0xffff888106f1de00 42 2 0 6 D 0xffff888106f1f140 kworker/6:0 0xffff888106f1af00 43 2 0 6 D 0xffff888106f1c240 kworker/6:0H 0xffff888106f41780 47 2 0 7 D 0xffff888106f42ac0 kworker/7:0 0xffff888106f40000 48 2 0 7 D 0xffff888106f41340 kworker/7:0H 0xffff888106f75e00 51 2 0 1 D 0xffff888106f77140 netns 0xffff888106f74680 53 2 0 0 D 0xffff888106f759c0 kworker/0:1 0xffff888237811780 56 2 0 2 D 0xffff888237812ac0 writeback 0xffff888237858000 60 2 0 3 D 0xffff888237859340 crypto 0xffff88823785de00 61 2 0 4 D 0xffff88823785f140 kintegrityd 0xffff88823785af00 62 2 0 6 D 0xffff88823785c240 kblockd 0xffff888237922f00 63 2 0 5 D 0xffff888237924240 md 0xffff888237924680 64 2 0 7 D 0xffff8882379259c0 edac-poller 0xffff888237920000 66 2 0 4 D 0xffff888237921340 kworker/4:1 0xffff888237925e00 67 2 0 2 R 0xffff888237927140 kworker/2:1 0xffff888236c61780 68 2 0 1 D 0xffff888236c62ac0 kworker/1:1 0xffff888236c60000 69 2 0 3 D 0xffff888236c61340 kworker/3:1 0xffff8882337a9780 96 2 0 6 D 0xffff8882337aaac0 kworker/6:1 0xffff88823306af00 101 2 0 7 D 0xffff88823306c240 kworker/u16:1 0xffff888233069780 103 2 0 7 D 0xffff88823306aac0 kworker/7:1 0xffff888233002f00 134 2 0 0 D 0xffff888233004240 kthrotld 0xffff888233004680 135 2 0 2 D 0xffff8882330059c0 acpi_thermal_pm 0xffff888233005e00 136 2 0 4 D 0xffff888233007140 kmpath_rdacd 0xffff888233000000 137 2 0 1 D 0xffff888233001340 kaluad 0xffff8882337ac680 138 2 0 5 D 0xffff8882337ad9c0 ipv6_addrconf 0xffff8882337aaf00 139 2 0 3 D 0xffff8882337ac240 kworker/3:2 0xffff8882337ade00 140 2 0 7 D 0xffff8882337af140 kstrp 0xffff8882337a8000 141 2 0 5 D 0xffff8882337a9340 kworker/5:1 0xffff8882330dc680 229 2 0 6 D 0xffff8882330dd9c0 kworker/6:2 0xffff888233601780 238 2 0 5 D 0xffff888233602ac0 kworker/5:2 0xffff888233734680 243 2 0 4 D 0xffff8882337359c0 kworker/4:2 0xffff888233731780 244 2 0 4 D 0xffff888233732ac0 kworker/4:3 0xffff888233735e00 391 2 0 4 D 0xffff888233737140 ata_sff 0xffff888233020000 398 2 0 4 D 0xffff888233021340 scsi_tmf_0 0xffff888233704680 400 2 0 4 D 0xffff8882337059c0 scsi_tmf_1 0xffff888233605e00 401 2 0 3 D 0xffff888233607140 kworker/u16:2 0xffff888233600000 403 2 0 1 D 0xffff888233601340 kworker/u16:3 0xffff88823306de00 420 2 0 0 D 0xffff88823306f140 kworker/0:2 0xffff888233068000 423 2 0 2 D 0xffff888233069340 kworker/2:1H 0xffff888233021780 424 2 0 5 D 0xffff888233022ac0 kworker/5:1H 0xffff888236c65e00 425 2 0 2 D 0xffff888236c67140 kworker/2:2 0xffff88823089c680 426 2 0 4 D 0xffff88823089d9c0 kworker/4:1H 0xffff888230899780 430 2 0 3 D 0xffff88823089aac0 kworker/3:1H 0xffff888230898000 431 2 0 1 D 0xffff888230899340 kworker/1:1H 0xffff88823089de00 432 2 0 1 D 0xffff88823089f140 kworker/1:2 0xffff88823089af00 433 2 0 7 D 0xffff88823089c240 kworker/7:1H 0xffff888230929780 435 2 0 6 D 0xffff88823092aac0 kworker/6:1H 0xffff88823092de00 446 2 0 0 D 0xffff88823092f140 kworker/0:1H 0xffff88823092c680 452 2 0 4 D 0xffff88823092d9c0 ext4-rsv-conver 0xffff88823092af00 511 2 0 6 D 0xffff88823092c240 kworker/6:3 0xffff888233634680 513 2 0 7 D 0xffff8882336359c0 kworker/7:2 0xffff888233632f00 519 2 0 1 D 0xffff888233634240 kworker/1:3 0xffff8882330daf00 553 1 0 5 S 0xffff8882330dc240 systemd-journal 0xffff8882356eaf00 567 1 0 0 S 0xffff8882356ec240 systemd-udevd 0xffff888234b0de00 688 2 0 0 D 0xffff888234b0f140 ttm_swap 0xffff888234b08000 702 2 0 4 D 0xffff888234b09340 kworker/4:4 0xffff888233630000 705 2 0 3 D 0xffff888233631340 ext4-rsv-conver 0xffff888233038000 715 1 0 1 S 0xffff888233039340 mdadm 0xffff88823303de00 716 1 0 1 S 0xffff88823303f140 auditd 0xffff888232a10000 717 1 0 4 S 0xffff888232a11340 auditd 0xffff888233039780 719 2 0 4 D 0xffff88823303aac0 kworker/4:5 0xffff8882330f5e00 735 1 0 0 S 0xffff8882330f7140 dbus-daemon 0xffff888235688000 742 1 0 5 S 0xffff888235689340 chronyd 0xffff8882361ade00 745 1 0 7 S 0xffff8882361af140 irqbalance 0xffff88823314af00 746 1 0 2 S 0xffff88823314c240 gmain 0xffff8882330dde00 753 1 0 5 S 0xffff8882330df140 NetworkManager 0xffff888232a15e00 758 1 0 4 S 0xffff888232a17140 gmain 0xffff888232a11780 759 1 0 2 S 0xffff888232a12ac0 gdbus 0xffff8882330d9780 755 1 0 5 S 0xffff8882330daac0 systemd-logind 0xffff888233148000 756 2 0 3 D 0xffff888233149340 kworker/3:3 0xffff88823314de00 757 2 0 3 D 0xffff88823314f140 kworker/3:4 0xffff8882329dde00 763 2 0 5 D 0xffff8882329df140 rpciod 0xffff8882329daf00 764 2 0 0 D 0xffff8882329dc240 kworker/u17:0 0xffff8882329d9780 765 2 0 2 D 0xffff8882329daac0 xprtiod 0xffff888233602f00 766 1 0 0 S 0xffff888233604240 sshd 0xffff88823568de00 783 753 0 4 S 0xffff88823568f140 dhclient 0xffff888234b1de00 794 1 0 0 S 0xffff888234b1f140 gssproxy 0xffff8882361a8000 801 1 0 4 S 0xffff8882361a9340 gssproxy 0xffff8882361a9780 802 1 0 3 S 0xffff8882361aaac0 gssproxy 0xffff8882361aaf00 803 1 0 6 S 0xffff8882361ac240 gssproxy 0xffff8882361ac680 804 1 0 7 S 0xffff8882361ad9c0 gssproxy 0xffff888233631780 805 1 0 3 S 0xffff888233632ac0 gssproxy 0xffff888233701780 816 1 0 7 S 0xffff888233702ac0 crond 0xffff888233705e00 817 1 0 2 S 0xffff888233707140 agetty 0xffff888233022f00 1072 2 0 0 D 0xffff888233024240 kworker/0:3 0xffff888233025e00 1080 1 0 1 S 0xffff888233027140 login 0xffff8882330d8000 1084 1 0 6 S 0xffff8882330d9340 systemd 0xffff888230a6af00 1085 1084 0 3 S 0xffff888230a6c240 (sd-pam) 0xffff88823568c680 1092 1080 1 2 R 0xffff88823568d9c0 *bash -
设置断点 bp
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查看断点 bl
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清除断点 bc
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开启断点 be
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关闭断点 bd
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单步执行 ss
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帮助 help / ?
[3]kdb> ? Command Usage Description----------------------------------------------------------md <vaddr> Display Memory Contents, also mdWcN, e.g. md8c1mdr <vaddr> <bytes> Display Raw Memorymdp <paddr> <bytes> Display Physical Memorymds <vaddr> Display Memory Symbolicallymm <vaddr> <contents> Modify Memory Contentsgo [<vaddr>] Continue Executionrd Display Registersrm <reg> <contents> Modify Registersef <vaddr> Display exception framebt [<vaddr>] Stack tracebackbtp <pid> Display stack for process <pid>bta [D|R|S|T|C|Z|E|U|I|M|A]Backtrace all processes matching state flagbtc Backtrace current process on each cpubtt <vaddr> Backtrace process given its struct task addressenv Show environment variablesset Set environment variableshelp Display Help Message? Display Help Messagecpu <cpunum> Switch to new cpukgdb Enter kgdb modeps [<flags>|A] Display active task listpid <pidnum> Switch to another taskreboot Reboot the machine immediatelylsmod List loaded kernel modulessr <key> Magic SysRq keydmesg [lines] Display syslog bufferdefcmd name "usage" "help" Define a set of commands, down to endefcmdkill <-signal> <pid> Send a signal to a processsummary Summarize the systemper_cpu <sym> [<bytes>] [<cpu>]Display per_cpu variablesgrephelp Display help on | grepbp [<vaddr>] Set/Display breakpointsbl [<vaddr>] Display breakpointsbph [<vaddr>] [datar [length]|dataw [length]] Set hw brkbc <bpnum> Clear Breakpointbe <bpnum> Enable Breakpointbd <bpnum> Disable Breakpointss Single Stepdumpcommon Common kdb debuggingdumpall First line debuggingdumpcpu Same as dumpall but only tasks on cpusftdump [skip_#lines] [cpu] Dump ftrace log
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