Linux kernel debug技巧----开启DEBUG选项

作者：wowo 发布于：2016-11-1 19:39

分类：Linux应用技巧

kernel的source code中有很多使用pr_debug/dev_dbg输出的日志信息(例如device tree解析的代码，drivers/of/fdt.c)。默认情况下，kernel不会将这些日志输出到控制台上，除非：

1)开启了DEBUG宏，并且

2)kernel printk的默认日志级别大于7

看似简单，不过我相信每个人都问过这样的问题(不管是问自己还是问别人，特别是在调试kernel启动过程的时候，例如device tree的匹配、device probe等)：怎么开启DEBUG选项？

之所以有这篇短文，是因为我也问过(不止一次)，于是就记录如下：

1)开启了DEBUG宏

其实开启DEBUG宏的方法很简单，在需要pr_debug/dev_dbg输出的模块开头，直接#define DEBUG即可，kernel中有一个例子：

/* init/main.c */

#define DEBUG           /* Enable initcall_debug */

不过这种方法有个缺点：我们必须准确的知道需要debug那个C文件，如果想大网撒鱼(例如，想debug为什么新修改的DTS文件没有起作用，而又对kernel fdt的代码不是很熟悉)，就麻烦了。这里我给一个大杀器：在编译kernel的时候，通过KCFLAGS直接传递，这样可以全局生效，如下(以本站的“X Project”为例)：

diff --git a/Makefile b/Makefile

index 0835b1c..59625f4 100644

--- a/Makefile

+++ b/Makefile

@@ -83,7 +83,7 @@ kernel-config:

kernel:

mkdir -p $(KERNEL_OUT_DIR)

make -C $(KERNEL_DIR) CROSS_COMPILE=$(CROSS_COMPILE) KBUILD_OUTPUT=$(KERNEL_OUT_DIR) ARCH=$(BOARD_ARCH) $(KERNEL_D

-       make -C $(KERNEL_DIR) CROSS_COMPILE=$(CROSS_COMPILE) KBUILD_OUTPUT=$(KERNEL_OUT_DIR) ARCH=$(BOARD_ARCH) $(KERNEL_T

+       make -C $(KERNEL_DIR) CROSS_COMPILE=$(CROSS_COMPILE) KBUILD_OUTPUT=$(KERNEL_OUT_DIR) KCFLAGS=-DDEBUG ARCH=$(BOARD_

2)设置kernel printk的默认日志级别为8

修改printk的默认日志级别的方法有多种，例如直接修改printk.c(新kernel为printk.h)中的CONSOLE_LOGLEVEL_DEFAULT宏定义。不过修改kernel原生代码的方式稍显粗暴，我们还有优雅一些的手段，例如通过命令行参数的loglevel变量传递，如下：

diff --git a/arch/arm64/configs/xprj_defconfig b/arch/arm64/configs/xprj_defconfig

index 5d0d591..9335d3f 100644

--- a/arch/arm64/configs/xprj_defconfig

+++ b/arch/arm64/configs/xprj_defconfig

@@ -320,7 +320,7 @@ CONFIG_FORCE_MAX_ZONEORDER=11

#

# Boot options

#

-CONFIG_CMDLINE="earlycon=owl_serial"

+CONFIG_CMDLINE="earlycon=owl_serial loglevel=8"

CONFIG_CMDLINE_FORCE=y

# CONFIG_EFI is not set

3)修改完之后，编译并启动kernel看看效果吧(是不是很爽？)

Starting kernel ...

flushing dcache successfully.

[    0.000000] Booting Linux on physical CPU 0x0

[    0.000000] Linux version 4.6.0-rc5+ (pengo@ubuntu) (gcc version 4.8.3 20131202 (prerelease) (crosstool-NG linaro-1.13.1-4.8-2013.12 - Linaro GCC 2013.11) ) #17 SMP Tue Nov 1 03:52:32 PDT 2016

[    0.000000] Boot CPU: AArch64 Processor [410fd032]

[    0.000000] earlycon: owl_serial0 at I/O port 0x0 (options '')

[    0.000000] bootconsole [owl_serial0] enabled

[    0.000000] On node 0 totalpages: 524288

[    0.000000]   DMA zone: 8192 pages used for memmap

[    0.000000]   DMA zone: 0 pages reserved

[    0.000000]   DMA zone: 524288 pages, LIFO batch:31

[    0.000000]  -> unflatten_device_tree()

[    0.000000] Unflattening device tree:

[    0.000000] magic: d00dfeed

[    0.000000] size: 00001000

[    0.000000] version: 00000011

[    0.000000]   size is cb0, allocating...

[    0.000000]   unflattening ffffffc07ffed1c8...

[    0.000000] fixed up name for  ->

[    0.000000] fixed up name for memory -> memory

[    0.000000] fixed up name for chosen -> chosen

[    0.000000] fixed up name for interrupt-controller@e00f1000 -> interrupt-controller

[    0.000000] fixed up name for timer -> timer

[    0.000000]

[    0.000000] Failed to find device node for boot cpu

[    0.000000] missing boot CPU MPIDR, not enabling secondaries

[    0.000000] mask of set bits 0x0

[    0.000000] MPIDR hash: aff0[0] aff1[8] aff2[16] aff3[32] mask[0x0] bits[0]

[    0.000000] percpu: Embedded 14 pages/cpu @ffffffc07ffdd000 s28032 r0 d29312 u57344

[    0.000000] pcpu-alloc: s28032 r0 d29312 u57344 alloc=14*4096

[    0.000000] pcpu-alloc: [0] 0

[    0.000000] Detected VIPT I-cache on CPU0

[    0.000000] Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 516096

[    0.000000] Kernel command line: earlycon=owl_serial loglevel=8

[    0.000000] doing Booting kernel, parsing ARGS: 'earlycon=owl_serial loglevel=8'

[    0.000000] doing Booting kernel: earlycon='owl_serial'

[    0.000000] doing Booting kernel: loglevel='8'

[    0.000000] PID hash table entries: 4096 (order: 3, 32768 bytes)

[    0.000000] Dentry cache hash table entries: 262144 (order: 9, 2097152 bytes)

[    0.000000] Inode-cache hash table entries: 131072 (order: 8, 1048576 bytes)

[    0.000000] software IO TLB [mem 0x79cb3000-0x7dcb3000] (64MB) mapped at [ffffffc079cb3000-ffffffc07dcb2fff]

[    0.000000] Memory: 1993604K/2097152K available (1032K kernel code, 78K rwdata, 128K rodata, 120K init, 201K bss, 103548K reserved, 0K cma-reserved)

[    0.000000] Virtual kernel memory layout:

[    0.000000]     modules : 0xffffff8000000000 - 0xffffff8008000000   (   128 MB)

[    0.000000]     vmalloc : 0xffffff8008000000 - 0xffffffbdbfff0000   (   246 GB)

[    0.000000]       .text : 0xffffff8008080000 - 0xffffff8008182000   (  1032 KB)

[    0.000000]     .rodata : 0xffffff8008182000 - 0xffffff80081a3000   (   132 KB)

[    0.000000]       .init : 0xffffff80081a3000 - 0xffffff80081c1000   (   120 KB)

[    0.000000]       .data : 0xffffff80081c1000 - 0xffffff80081d4800   (    78 KB)

[    0.000000]     fixed   : 0xffffffbffe7fd000 - 0xffffffbffec00000   (  4108 KB)

[    0.000000]     PCI I/O : 0xffffffbffee00000 - 0xffffffbfffe00000   (    16 MB)

[    0.000000]     memory  : 0xffffffc000000000 - 0xffffffc080000000   (  2048 MB)

[    0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1

[    0.000000] Hierarchical RCU implementation.

[    0.000000]  Build-time adjustment of leaf fanout to 64.

[    0.000000]  RCU restricting CPUs from NR_CPUS=64 to nr_cpu_ids=1.

[    0.000000] RCU: Adjusting geometry for rcu_fanout_leaf=64, nr_cpu_ids=1

[    0.000000] NR_IRQS:64 nr_irqs:64 0

[    0.000000] of_irq_init: init /interrupt-controller@e00f1000 (ffffffc07ffed800), parent           (null)

[    0.000000] OF: ** translation for device /interrupt-controller@e00f1000 **

[    0.000000] OF: bus is default (na=2, ns=2) on /

[    0.000000] OF: translating address: 00000000 e00f1000

[    0.000000] OF: reached root node

[    0.000000] OF: ** translation for device /interrupt-controller@e00f1000 **

[    0.000000] OF: bus is default (na=2, ns=2) on /

[    0.000000] OF: translating address: 00000000 e00f2000

[    0.000000] OF: reached root node

[    0.000000] OF: ** translation for device /interrupt-controller@e00f1000 **

[    0.000000] OF: bus is default (na=2, ns=2) on /

[    0.000000] OF: translating address: 00000000 e00f2000

[    0.000000] OF: reached root node

[    0.000000] irq: Added domain (null)

[    0.000000] of_irq_parse_one: dev=/timer, index=0

[    0.000000]  intspec=1 intlen=12

[    0.000000]  intsize=3 intlen=12

[    0.000000] of_irq_parse_raw:  /interrupt-controller@e00f1000:00000001,0000000d,00000f08

[    0.000000] of_irq_parse_raw: ipar=/interrupt-controller@e00f1000, size=3

[    0.000000]  -> addrsize=0

[    0.000000]  -> got it !

[    0.000000] of_irq_parse_one: dev=/timer, index=1

[    0.000000]  intspec=1 intlen=12

[    0.000000]  intsize=3 intlen=12

[    0.000000] of_irq_parse_raw:  /interrupt-controller@e00f1000:00000001,0000000e,00000f08

[    0.000000] of_irq_parse_raw: ipar=/interrupt-controller@e00f1000, size=3

[    0.000000]  -> addrsize=0

[    0.000000]  -> got it !

[    0.000000] of_irq_parse_one: dev=/timer, index=2

[    0.000000]  intspec=1 intlen=12

[    0.000000]  intsize=3 intlen=12

[    0.000000] of_irq_parse_raw:  /interrupt-controller@e00f1000:00000001,0000000b,00000f08

[    0.000000] of_irq_parse_raw: ipar=/interrupt-controller@e00f1000, size=3

[    0.000000]  -> addrsize=0

[    0.000000]  -> got it !

[    0.000000] of_irq_parse_one: dev=/timer, index=3

[    0.000000]  intspec=1 intlen=12

[    0.000000]  intsize=3 intlen=12

[    0.000000] of_irq_parse_raw:  /interrupt-controller@e00f1000:00000001,0000000a,00000f08

[    0.000000] of_irq_parse_raw: ipar=/interrupt-controller@e00f1000, size=3

[    0.000000]  -> addrsize=0

[    0.000000]  -> got it !

[    0.000000] Architected cp15 timer(s) running at 24.00MHz (phys).

[    0.000000] clocksource: arch_sys_counter: mask: 0xffffffffffffff max_cycles: 0x588fe9dc0, max_idle_ns: 440795202592 ns

[    0.000031] sched_clock: 56 bits at 24MHz, resolution 41ns, wraps every 4398046511097ns

[    0.007999] Registered 0xffffff800816bf78 as sched_clock source

[    0.013906] Calibrating delay loop (skipped), value calculated using timer frequency.. 48.00 BogoMIPS (lpj=96000)

[    0.024093] pid_max: default: 4096 minimum: 301

[    0.028687] Mount-cache hash table entries: 4096 (order: 3, 32768 bytes)

[    0.035281] Mountpoint-cache hash table entries: 4096 (order: 3, 32768 bytes)

[    0.042468] kobject: 'fs' (ffffffc079802c00): kobject_add_internal: parent: '', set: ''

[    0.051687] No CPU information found in DT

[    0.055499] CPU0: cluster 0 core 0 thread -1 mpidr 0x00000080000000

[    0.061718] ASID allocator initialised with 65536 entries

[    0.067687] Brought up 1 CPUs

[    0.070031] SMP: Total of 1 processors activated.

[    0.074718] CPU: All CPU(s) started at EL2

[    0.079281] kobject: 'devices' (ffffffc079823a98): kobject_add_internal: parent: '', set: ''

[    0.088249] kobject: 'devices' (ffffffc079823a98): kobject_uevent_env

[    0.094656] kobject: 'devices' (ffffffc079823a98): kobject_uevent_env: attempted to send uevent without kset!

[    0.104531] kobject: 'dev' (ffffffc079823b00): kobject_add_internal: parent: '', set: ''

[    0.113624] kobject: 'block' (ffffffc079823b80): kobject_add_internal: parent: 'dev', set: ''

[    0.122656] kobject: 'char' (ffffffc079823c00): kobject_add_internal: parent: 'dev', set: ''

[    0.131562] kobject: 'bus' (ffffffc079823c98): kobject_add_internal: parent: '', set: ''

[    0.140687] kobject: 'bus' (ffffffc079823c98): kobject_uevent_env

[    0.146749] kobject: 'bus' (ffffffc079823c98): kobject_uevent_env: attempted to send uevent without kset!

[    0.156281] kobject: 'system' (ffffffc079823d18): kobject_add_internal: parent: 'devices', set: ''

[    0.165718] kobject: 'system' (ffffffc079823d18): kobject_uevent_env

[    0.172062] kobject: 'system' (ffffffc079823d18): kobject_uevent_env: attempted to send uevent without kset!

[    0.181843] kobject: 'class' (ffffffc079823d98): kobject_add_internal: parent: '', set: ''

[    0.191124] kobject: 'class' (ffffffc079823d98): kobject_uevent_env

[    0.197343] kobject: 'class' (ffffffc079823d98): kobject_uevent_env: attempted to send uevent without kset!

[    0.207062] kobject: 'firmware' (ffffffc079823e00): kobject_add_internal: parent: '', set: ''

[    0.216593] device: 'platform': device_add

[    0.220656] kobject: 'platform' (ffffff80081d2680): kobject_add_internal: parent: 'devices', set: 'devices'

[    0.230374] kobject: 'platform' (ffffff80081d2680): kobject_uevent_env

[    0.236874] kobject: 'platform' (ffffff80081d2680): kobject_uevent_env: filter function caused the event to drop!

[    0.247093] kobject: 'platform' (ffffffc079822818): kobject_add_internal: parent: 'bus', set: 'bus'

[    0.256124] kobject: 'platform' (ffffffc079822818): kobject_uevent_env

[    0.262624] kobject: 'platform' (ffffffc079822818): fill_kobj_path: path = '/bus/platform'

[    0.270843] kobject: 'devices' (ffffffc079823e98): kobject_add_internal: parent: 'platform', set: ''

[    0.280468] kobject: 'devices' (ffffffc079823e98): kobject_uevent_env

[    0.286874] kobject: 'devices' (ffffffc079823e98): kobject_uevent_env: filter function caused the event to drop!

[    0.297031] kobject: 'drivers' (ffffffc079823f18): kobject_add_internal: parent: 'platform', set: ''

[    0.306656] kobject: 'drivers' (ffffffc079823f18): kobject_uevent_env

[    0.313062] kobject: 'drivers' (ffffffc079823f18): kobject_uevent_env: filter function caused the event to drop!

[    0.323187] bus: 'platform': registered

[    0.326999] kobject: 'cpu' (ffffffc079822a18): kobject_add_internal: parent: 'bus', set: 'bus'

[    0.335593] kobject: 'cpu' (ffffffc079822a18): kobject_uevent_env

[    0.341656] kobject: 'cpu' (ffffffc079822a18): fill_kobj_path: path = '/bus/cpu'

[    0.349031] kobject: 'devices' (ffffffc079823f98): kobject_add_internal: parent: 'cpu', set: ''

[    0.358218] kobject: 'devices' (ffffffc079823f98): kobject_uevent_env

[    0.364624] kobject: 'devices' (ffffffc079823f98): kobject_uevent_env: filter function caused the event to drop!

[    0.374749] kobject: 'drivers' (ffffffc079820d18): kobject_add_internal: parent: 'cpu', set: ''

[    0.383937] kobject: 'drivers' (ffffffc079820d18): kobject_uevent_env

[    0.390374] kobject: 'drivers' (ffffffc079820d18): kobject_uevent_env: filter function caused the event to drop!

[    0.400499] bus: 'cpu': registered

[    0.403874] device: 'cpu': device_add

[    0.407531] kobject: 'cpu' (ffffffc079822c10): kobject_add_internal: parent: 'system', set: 'devices'

[    0.416718] kobject: 'cpu' (ffffffc079822c10): kobject_uevent_env

[    0.422781] kobject: 'cpu' (ffffffc079822c10): kobject_uevent_env: filter function caused the event to drop!

[    0.432562] kobject: 'container' (ffffffc079822e18): kobject_add_internal: parent: 'bus', set: 'bus'

[    0.441656] kobject: 'container' (ffffffc079822e18): kobject_uevent_env

[    0.448249] kobject: 'container' (ffffffc079822e18): fill_kobj_path: path = '/bus/container'

[    0.456656] kobject: 'devices' (ffffffc079820d98): kobject_add_internal: parent: 'container', set: ''

[    0.466374] kobject: 'devices' (ffffffc079820d98): kobject_uevent_env

[    0.472781] kobject: 'devices' (ffffffc079820d98): kobject_uevent_env: filter function caused the event to drop!

[    0.482937] kobject: 'drivers' (ffffffc079820e18): kobject_add_internal: parent: 'container', set: ''

[    0.492624] kobject: 'drivers' (ffffffc079820e18): kobject_uevent_env

[    0.499031] kobject: 'drivers' (ffffffc079820e18): kobject_uevent_env: filter function caused the event to drop!

[    0.509187] bus: 'container': registered

[    0.513093] device: 'container': device_add

[    0.517249] kobject: 'container' (ffffffc079824010): kobject_add_internal: parent: 'system', set: 'devices'

[    0.526937] kobject: 'container' (ffffffc079824010): kobject_uevent_env

[    0.533531] kobject: 'container' (ffffffc079824010): kobject_uevent_env: filter function caused the event to drop!

[    0.543843] kobject: 'devicetree' (ffffffc079820f98): kobject_add_internal: parent: 'firmware', set: ''

[    0.553718] kobject: 'devicetree' (ffffffc079820f98): kobject_uevent_env

[    0.560406] kobject: 'devicetree' (ffffffc079820f98): kobject_uevent_env: attempted to send uevent without kset!

[    0.570531] doing early, parsing ARGS: 'earlycon=owl_serial loglevel=8'

[    0.577124] doing early: earlycon='owl_serial'

[    0.581562] doing early: loglevel='8'

[    0.585187] doing core, parsing ARGS: 'earlycon=owl_serial loglevel=8'

[    0.591687] doing core: earlycon='owl_serial'

[    0.596031] doing core: loglevel='8'

[    0.599593] kobject: 'kernel' (ffffffc079825000): kobject_add_internal: parent: '', set: ''

[    0.608937] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns

[    0.618656] doing postcore, parsing ARGS: 'earlycon=owl_serial loglevel=8'

[    0.625499] doing postcore: earlycon='owl_serial'

[    0.630156] doing postcore: loglevel='8'

[    0.634062] device class 'bdi': registering

[    0.638218] kobject: 'bdi' (ffffffc079824218): kobject_add_internal: parent: 'class', set: 'class'

[    0.647156] kobject: 'bdi' (ffffffc079824218): kobject_uevent_env

[    0.653218] kobject: 'bdi' (ffffffc079824218): fill_kobj_path: path = '/class/bdi'

[    0.660781] kobject: 'mm' (ffffffc079825100): kobject_add_internal: parent: 'kernel', set: ''

[    0.669781] kobject: 'amba' (ffffffc079824418): kobject_add_internal: parent: 'bus', set: 'bus'

[    0.678437] kobject: 'amba' (ffffffc079824418): kobject_uevent_env

[    0.684593] kobject: 'amba' (ffffffc079824418): fill_kobj_path: path = '/bus/amba'

[    0.692124] kobject: 'devices' (ffffffc079825198): kobject_add_internal: parent: 'amba', set: ''

[    0.701406] kobject: 'devices' (ffffffc079825198): kobject_uevent_env

[    0.707812] kobject: 'devices' (ffffffc079825198): kobject_uevent_env: filter function caused the event to drop!

[    0.717968] kobject: 'drivers' (ffffffc079825218): kobject_add_internal: parent: 'amba', set: ''

[    0.727249] kobject: 'drivers' (ffffffc079825218): kobject_uevent_env

[    0.733656] kobject: 'drivers' (ffffffc079825218): kobject_uevent_env: filter function caused the event to drop!

[    0.743781] bus: 'amba': registered

[    0.747249] device class 'tty': registering

[    0.751406] kobject: 'tty' (ffffffc079824618): kobject_add_internal: parent: 'class', set: 'class'

[    0.760343] kobject: 'tty' (ffffffc079824618): kobject_uevent_env

[    0.766406] kobject: 'tty' (ffffffc079824618): fill_kobj_path: path = '/class/tty'

[    0.773937] doing arch, parsing ARGS: 'earlycon=owl_serial loglevel=8'

[    0.780437] doing arch: earlycon='owl_serial'

[    0.784781] doing arch: loglevel='8'

[    0.788343] vdso: 2 pages (1 code @ ffffff8008186000, 1 data @ ffffff80081c8000)

[    0.795874] DMA: preallocated 256 KiB pool for atomic allocations

[    0.801781] of_platform_bus_create() - skipping /memory, no compatible prop

[    0.808687] of_platform_bus_create() - skipping /chosen, no compatible prop

[    0.815656] OF: ** translation for device /interrupt-controller@e00f1000 **

[    0.822562] OF: bus is default (na=2, ns=2) on /

[    0.827156] OF: translating address: 00000000 e00f1000

[    0.832281] OF: reached root node

[    0.835562] OF: ** translation for device /interrupt-controller@e00f1000 **

[    0.842499] OF: bus is default (na=2, ns=2) on /

[    0.847093] OF: translating address: 00000000 e00f2000

[    0.852218] OF: reached root node

[    0.855499] of_irq_parse_one: dev=/interrupt-controller@e00f1000, index=0

[    0.862249] OF: ** translation for device /interrupt-controller@e00f1000 **

[    0.869187] OF: bus is default (na=2, ns=2) on /

[    0.873781] OF: translating address: 00000000 e00f1000

[    0.878906] OF: reached root node

[    0.882187] OF: ** translation for device /interrupt-controller@e00f1000 **

[    0.889124] OF: bus is default (na=2, ns=2) on /

[    0.893718] OF: translating address: 00000000 e00f2000

[    0.898843] OF: reached root node

[    0.902124] OF: ** translation for device /interrupt-controller@e00f1000 **

[    0.909062] OF: bus is default (na=2, ns=2) on /

[    0.913656] OF: translating address: 00000000 e00f1000

[    0.918781] OF: reached root node

[    0.922062] of_dma_get_range: no dma-ranges found for node(/interrupt-controller@e00f1000)

[    0.930312] platform e00f1000.interrupt-controller: device is not dma coherent

[    0.937499] platform e00f1000.interrupt-controller: device is not behind an iommu

[    0.944937] device: 'e00f1000.interrupt-controller': device_add

[    0.950843] kobject: 'e00f1000.interrupt-controller' (ffffffc079824820): kobject_add_internal: parent: 'platform', set: 'devices'

[    0.962437] bus: 'platform': add device e00f1000.interrupt-controller

[    0.968874] kobject: 'e00f1000.interrupt-controller' (ffffffc079824820): kobject_uevent_env

[    0.977187] kobject: 'e00f1000.interrupt-controller' (ffffffc079824820): fill_kobj_path: path = '/devices/platform/e00f1000.interrupt-controller'

[    0.990218] of_irq_parse_one: dev=/timer, index=0

[    0.994874]  intspec=1 intlen=12

[    0.998062]  intsize=3 intlen=12

[    1.001281] of_irq_parse_raw:  /interrupt-controller@e00f1000:00000001,0000000d,00000f08

[    1.009343] of_irq_parse_raw: ipar=/interrupt-controller@e00f1000, size=3

[    1.016093]  -> addrsize=0

[    1.018781]  -> got it !

[    1.021281] of_irq_parse_one: dev=/timer, index=1

[    1.025968]  intspec=1 intlen=12

[    1.029187]  intsize=3 intlen=12

[    1.032374] of_irq_parse_raw:  /interrupt-controller@e00f1000:00000001,0000000e,00000f08

[    1.040437] of_irq_parse_raw: ipar=/interrupt-controller@e00f1000, size=3

[    1.047218]  -> addrsize=0

[    1.049906]  -> got it !

[    1.052406] of_irq_parse_one: dev=/timer, index=2

[    1.057093]  intspec=1 intlen=12

[    1.060281]  intsize=3 intlen=12

[    1.063499] of_irq_parse_raw:  /interrupt-controller@e00f1000:00000001,0000000b,00000f08

[    1.071562] of_irq_parse_raw: ipar=/interrupt-controller@e00f1000, size=3

[    1.078312]  -> addrsize=0

[    1.080999]  -> got it !

[    1.083531] of_irq_parse_one: dev=/timer, index=3

[    1.088187]  intspec=1 intlen=12

[    1.091406]  intsize=3 intlen=12

[    1.094624] of_irq_parse_raw:  /interrupt-controller@e00f1000:00000001,0000000a,00000f08

[    1.102687] of_irq_parse_raw: ipar=/interrupt-controller@e00f1000, size=3

[    1.109437]  -> addrsize=0

[    1.112124]  -> got it !

[    1.114624] of_irq_parse_one: dev=/timer, index=4

[    1.119312]  intspec=1 intlen=12

[    1.122531]  intsize=3 intlen=12

[    1.125718] of_irq_parse_one: dev=/timer, index=0

[    1.130406]  intspec=1 intlen=12

[    1.133624]  intsize=3 intlen=12

[    1.136812] of_irq_parse_raw:  /interrupt-controller@e00f1000:00000001,0000000d,00000f08

[    1.144874] of_irq_parse_raw: ipar=/interrupt-controller@e00f1000, size=3

[    1.151624]  -> addrsize=0

[    1.154312]  -> got it !

[    1.156843] of_irq_parse_one: dev=/timer, index=1

[    1.161531]  intspec=1 intlen=12

[    1.164718]  intsize=3 intlen=12

[    1.167937] of_irq_parse_raw:  /interrupt-controller@e00f1000:00000001,0000000e,00000f08

[    1.175999] of_irq_parse_raw: ipar=/interrupt-controller@e00f1000, size=3

[    1.182749]  -> addrsize=0

[    1.185437]  -> got it !

[    1.187968] of_irq_parse_one: dev=/timer, index=2

[    1.192624]  intspec=1 intlen=12

[    1.195843]  intsize=3 intlen=12

[    1.199031] of_irq_parse_raw:  /interrupt-controller@e00f1000:00000001,0000000b,00000f08

[    1.207093] of_irq_parse_raw: ipar=/interrupt-controller@e00f1000, size=3

[    1.213874]  -> addrsize=0

[    1.216562]  -> got it !

[    1.219062] of_irq_parse_one: dev=/timer, index=3

[    1.223749]  intspec=1 intlen=12

[    1.226968]  intsize=3 intlen=12

[    1.230156] of_irq_parse_raw:  /interrupt-controller@e00f1000:00000001,0000000a,00000f08

[    1.238218] of_irq_parse_raw: ipar=/interrupt-controller@e00f1000, size=3

[    1.244968]  -> addrsize=0

[    1.247656]  -> got it !

[    1.250187] of_dma_get_range: no dma-ranges found for node(/timer)

[    1.256343] platform timer: device is not dma coherent

[    1.261437] platform timer: device is not behind an iommu

[    1.266812] device: 'timer': device_add

[    1.270624] kobject: 'timer' (ffffffc079824a20): kobject_add_internal: parent: 'platform', set: 'devices'

[    1.280156] bus: 'platform': add device timer

[    1.284499] kobject: 'timer' (ffffffc079824a20): kobject_uevent_env

[    1.290749] kobject: 'timer' (ffffffc079824a20): fill_kobj_path: path = '/devices/platform/timer'

[    1.299593] doing subsys, parsing ARGS: 'earlycon=owl_serial loglevel=8'

[    1.306249] doing subsys: earlycon='owl_serial'

[    1.310749] doing subsys: loglevel='8'

[    1.314499] device: 'cpu0': device_add

[    1.318218] kobject: 'cpu0' (ffffffc07ffe1468): kobject_add_internal: parent: 'cpu', set: 'devices'

[    1.327218] bus: 'cpu': add device cpu0

[    1.331031] kobject: 'cpu0' (ffffffc07ffe1468): kobject_uevent_env

[    1.337187] kobject: 'cpu0' (ffffffc07ffe1468): fill_kobj_path: path = '/devices/system/cpu/cpu0'

[    1.346156] device class 'misc': registering

[    1.350281] kobject: 'misc' (ffffffc079824e18): kobject_add_internal: parent: 'class', set: 'class'

[    1.359281] kobject: 'misc' (ffffffc079824e18): kobject_uevent_env

[    1.365437] kobject: 'misc' (ffffffc079824e18): fill_kobj_path: path = '/class/misc'

[    1.373156] device class 'power_supply': registering

[    1.378093] kobject: 'power_supply' (ffffffc079803018): kobject_add_internal: parent: 'class', set: 'class'

[    1.387812] kobject: 'power_supply' (ffffffc079803018): kobject_uevent_env

[    1.394656] kobject: 'power_supply' (ffffffc079803018): fill_kobj_path: path = '/class/power_supply'

[    1.403749] doing fs, parsing ARGS: 'earlycon=owl_serial loglevel=8'

[    1.410093] doing fs: earlycon='owl_serial'

[    1.414249] doing fs: loglevel='8'

[    1.417656] clocksource: Switched to clocksource arch_sys_counter

[    1.423718] device class 'mem': registering

[    1.427843] kobject: 'mem' (ffffffc079827018): kobject_add_internal: parent: 'class', set: 'class'

[    1.436781] kobject: 'mem' (ffffffc079827018): kobject_uevent_env

[    1.442843] kobject: 'mem' (ffffffc079827018): fill_kobj_path: path = '/class/mem'

[    1.450374] device: 'null': device_add

[    1.454124] kobject: 'virtual' (ffffffc079826080): kobject_add_internal: parent: 'devices', set: ''

[    1.463656] kobject: 'mem' (ffffffc079826100): kobject_add_internal: parent: 'virtual', set: '(null)'

[    1.472843] kobject: 'null' (ffffffc079827210): kobject_add_internal: parent: 'mem', set: 'devices'

[    1.481843] kobject: 'null' (ffffffc079827210): kobject_uevent_env

[    1.487999] kobject: 'null' (ffffffc079827210): fill_kobj_path: path = '/devices/virtual/mem/null'

[    1.496937] device: 'zero': device_add

[    1.500656] kobject: 'zero' (ffffffc079827410): kobject_add_internal: parent: 'mem', set: 'devices'

[    1.509656] kobject: 'zero' (ffffffc079827410): kobject_uevent_env

[    1.515812] kobject: 'zero' (ffffffc079827410): fill_kobj_path: path = '/devices/virtual/mem/zero'

[    1.524749] device: 'full': device_add

[    1.528468] kobject: 'full' (ffffffc079827610): kobject_add_internal: parent: 'mem', set: 'devices'

[    1.537468] kobject: 'full' (ffffffc079827610): kobject_uevent_env

[    1.543624] kobject: 'full' (ffffffc079827610): fill_kobj_path: path = '/devices/virtual/mem/full'

[    1.552562] device: 'random': device_add

[    1.556468] kobject: 'random' (ffffffc079827810): kobject_add_internal: parent: 'mem', set: 'devices'

[    1.565656] kobject: 'random' (ffffffc079827810): kobject_uevent_env

[    1.571968] kobject: 'random' (ffffffc079827810): fill_kobj_path: path = '/devices/virtual/mem/random'

[    1.581249] device: 'urandom': device_add

[    1.585249] kobject: 'urandom' (ffffffc079827a10): kobject_add_internal: parent: 'mem', set: 'devices'

[    1.594499] kobject: 'urandom' (ffffffc079827a10): kobject_uevent_env

[    1.600937] kobject: 'urandom' (ffffffc079827a10): fill_kobj_path: path = '/devices/virtual/mem/urandom'

[    1.610374] device: 'kmsg': device_add

[    1.614093] kobject: 'kmsg' (ffffffc079827c10): kobject_add_internal: parent: 'mem', set: 'devices'

[    1.623124] kobject: 'kmsg' (ffffffc079827c10): kobject_uevent_env

[    1.629249] kobject: 'kmsg' (ffffffc079827c10): fill_kobj_path: path = '/devices/virtual/mem/kmsg'

[    1.638187] device: 'tty': device_add

[    1.641843] kobject: 'tty' (ffffffc079826280): kobject_add_internal: parent: 'virtual', set: '(null)'

[    1.651031] kobject: 'tty' (ffffffc079827e10): kobject_add_internal: parent: 'tty', set: 'devices'

[    1.659937] kobject: 'tty' (ffffffc079827e10): kobject_uevent_env

[    1.665999] kobject: 'tty' (ffffffc079827e10): fill_kobj_path: path = '/devices/virtual/tty/tty'

[    1.674781] device: 'console': device_add

[    1.678749] kobject: 'console' (ffffffc079829010): kobject_add_internal: parent: 'tty', set: 'devices'

[    1.688031] kobject: 'console' (ffffffc079829010): kobject_uevent_env

[    1.694437] kobject: 'console' (ffffffc079829010): fill_kobj_path: path = '/devices/virtual/tty/console'

[    1.703937] doing device, parsing ARGS: 'earlycon=owl_serial loglevel=8'

[    1.710562] doing device: earlycon='owl_serial'

[    1.715062] doing device: loglevel='8'

[    1.718812] bus: 'platform': add driver alarmtimer

[    1.723562] kobject: 'alarmtimer' (ffffffc079828600): kobject_add_internal: parent: 'drivers', set: 'drivers'

[    1.733437] kobject: 'alarmtimer' (ffffffc079828600): kobject_uevent_env

[    1.740124] kobject: 'alarmtimer' (ffffffc079828600): fill_kobj_path: path = '/bus/platform/drivers/alarmtimer'

[    1.750156] Registering platform device 'alarmtimer'. Parent at platform

[    1.756843] device: 'alarmtimer': device_add

[    1.761093] kobject: 'alarmtimer' (ffffffc079829220): kobject_add_internal: parent: 'platform', set: 'devices'

[    1.771062] bus: 'platform': add device alarmtimer

[    1.775812] kobject: 'alarmtimer' (ffffffc079829220): kobject_uevent_env

[    1.782499] kobject: 'alarmtimer' (ffffffc079829220): fill_kobj_path: path = '/devices/platform/alarmtimer'

[    1.792218] bus: 'platform': driver_probe_device: matched device alarmtimer with driver alarmtimer

[    1.801124] bus: 'platform': really_probe: probing driver alarmtimer with device alarmtimer

[    1.809437] devices_kset: Moving alarmtimer to end of list

[    1.814906] driver: 'alarmtimer': driver_bound: bound to device 'alarmtimer'

[    1.821937] bus: 'platform': really_probe: bound device alarmtimer to driver alarmtimer

[    1.829999] workingset: timestamp_bits=60 max_order=19 bucket_order=0

[    1.836312] Failed to find cpu0 device node

[    1.840468] Unable to detect cache hierarchy from DT for CPU 0

[    1.846281] bus: 'platform': add driver gpio-clk

[    1.850874] kobject: 'gpio-clk' (ffffffc079828900): kobject_add_internal: parent: 'drivers', set: 'drivers'

[    1.860593] kobject: 'gpio-clk' (ffffffc079828900): kobject_uevent_env

[    1.867093] kobject: 'gpio-clk' (ffffffc079828900): fill_kobj_path: path = '/bus/platform/drivers/gpio-clk'

[    1.876781] doing late, parsing ARGS: 'earlycon=owl_serial loglevel=8'

[    1.883281] doing late: earlycon='owl_serial'

[    1.887624] doing late: loglevel='8'

[    1.891187] device: 'cpu_dma_latency': device_add

[    1.895843] kobject: 'misc' (ffffffc079826780): kobject_add_internal: parent: 'virtual', set: '(null)'

[    1.905124] kobject: 'cpu_dma_latency' (ffffffc079829610): kobject_add_internal: parent: 'misc', set: 'devices'

[    1.915187] kobject: 'cpu_dma_latency' (ffffffc079829610): kobject_uevent_env

[    1.922281] kobject: 'cpu_dma_latency' (ffffffc079829610): fill_kobj_path: path = '/devices/virtual/misc/cpu_dma_latency'

[    1.933218] device: 'network_latency': device_add

[    1.937874] kobject: 'network_latency' (ffffffc079829810): kobject_add_internal: parent: 'misc', set: 'devices'

[    1.947937] kobject: 'network_latency' (ffffffc079829810): kobject_uevent_env

[    1.955031] kobject: 'network_latency' (ffffffc079829810): fill_kobj_path: path = '/devices/virtual/misc/network_latency'

[    1.965968] device: 'network_throughput': device_add

[    1.970906] kobject: 'network_throughput' (ffffffc079829a10): kobject_add_internal: parent: 'misc', set: 'devices'

[    1.981218] kobject: 'network_throughput' (ffffffc079829a10): kobject_uevent_env

[    1.988593] kobject: 'network_throughput' (ffffffc079829a10): fill_kobj_path: path = '/devices/virtual/misc/network_throughput'

[    2.000031] device: 'memory_bandwidth': device_add

[    2.004781] kobject: 'memory_bandwidth' (ffffffc079829c10): kobject_add_internal: parent: 'misc', set: 'devices'

[    2.014937] kobject: 'memory_bandwidth' (ffffffc079829c10): kobject_uevent_env

[    2.022124] kobject: 'memory_bandwidth' (ffffffc079829c10): fill_kobj_path: path = '/devices/virtual/misc/memory_bandwidth'

[    2.033437] Warning: unable to open an initial console.

[    2.038531] Freeing unused kernel memory: 120K (ffffff80081a3000 - ffffff80081c1000)

[    2.046124] This architecture does not have kernel memory protection.

[    2.052593] Kernel panic - not syncing: No working init found.  Try passing init= option to kernel. See Linux Documentation/init.txt for guidance.

[    2.065624] Kernel Offset: disabled

[    2.069093] Memory Limit: none

[    2.072124] ---[ end Kernel panic - not syncing: No working init found.  Try passing init= option to kernel. See Linux Documentation/init.txt for guidance.

原创文章，转发请注明出处。蜗窝科技，www.wowotech.net。

评论：

Jere

2019-07-17 21:42

@wowo，您好，

我在在kernel/Makefile中，加入KCFLAGS += -DDEBUG，然后make编译出zImage，烧到板子里，启动会停在starting kernel就没任何打印了，不加KCFLAGS += -DDEBUG的zImage可以正常启动。您有没有遇到这种情况？

谢谢

大鱼

2019-08-07 11:28

@Jere：打印太多了？

L

2019-05-10 19:46

我在linux的顶层Makefile中

KBUILD_CFLAGS 后添加 -DDEBUG

由于linux里面的c文件有很多定义了DEBUG，编译时会报重复定义DEBUG的错误，怎么比较好的解决呢，谢谢

gongcm

2019-05-31 13:39

@L：直接在顶层makefile中 加上 KCFLAGS += -DDEBUG

uxer

2019-07-10 10:17

@gongcm：在kernel/Makefile中，加入KCFLAGS += -DDEBUG，还是会报错，重复定义DEBUG

EP

2019-09-03 17:52

@uxer：KBUILD_CFLAGS   += -w

但一般打印太多，开机卡死，最好不要在顶层的Makefile中添加

肤了个浅

2017-11-08 10:38

去掉DEBUG这个宏之后，dev_dbg这个函数还会编译进去吗？

2017-11-09 18:19

@肤了个浅：不会了，你可以去看代码:-)

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