Linux dmesg日志异常原因分析 - 问答

dmesg（display message或者driver message）是Linux系统中的一个命令，用于显示内核启动信息和运行时的硬件设备状态信息。当你在Linux系统中遇到问题时，dmesg命令可以帮助你找到问题的根源。以下是一些常见的dmesg日志异常原因及其分析方法：

1. 硬件故障

表现：日志中出现硬件相关的错误信息，如设备未找到、驱动加载失败等。
分析：检查硬件连接是否正常，尝试更换硬件或更新驱动程序。

2. 驱动问题

表现：特定设备的驱动程序加载失败或出现错误。
分析：确认驱动程序是否正确安装，查看是否有更新的驱动版本可用。

3. 内存问题

表现：日志中出现内存相关的错误，如内存不足、内存泄漏等。
分析：使用free -m命令查看内存使用情况，使用vmstat监控内存状态。

4. CPU问题

表现：日志中出现CPU过热、频率异常等信息。
分析：检查散热系统是否正常工作，考虑更换散热器或风扇。

5. 文件系统错误

表现：日志中出现文件系统挂载失败、读写错误等信息。
分析：使用fsck命令检查和修复文件系统错误。

6. 网络问题

表现：日志中出现网络连接失败、丢包等信息。
分析：检查网络配置，使用ping、traceroute等工具诊断网络问题。

7. 内核参数配置错误

表现：日志中出现内核参数配置不当导致的错误。
分析：检查/etc/sysctl.conf文件，确保内核参数配置正确。

8. 软件冲突

表现：日志中出现软件包冲突、依赖问题等信息。
分析：使用apt、yum等包管理工具检查和解决软件冲突。

分析步骤

查看日志：使用dmesg命令查看最新的日志信息。
```
dmesg | less
```
过滤关键信息：使用grep命令过滤出关键错误信息。
```
dmesg | grep -i error
```
结合其他工具：使用lshw、lsusb、lspci等工具查看硬件状态。
查阅文档：查阅相关硬件和软件的官方文档，了解错误代码的含义。
搜索解决方案：在搜索引擎或技术论坛中搜索错误信息，查找解决方案。

示例

假设你在dmesg日志中看到以下信息：

[    0.000000] Linux version 5.4.0-42-generic (buildd@lgw01-amd64-039) (gcc version 9.3.0 (Ubuntu 9.3.0-10ubuntu2)) #46~18.04.1-Ubuntu SMP Fri Jul 10 00:24:02 UTC 2020
[    0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-5.4.0-42-generic root=UUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx ro quiet splash vt.handoff=7
[    0.000000] KERNEL supported cpus:
[    0.000000]   Intel GenuineIntel
[    0.000000]   AMD AuthenticAMD
[    0.000000]   Centaur CentaurHauls
[    0.000000] x86/fpu: Supporting XSAVE feature 0x001: 'x87 floating point registers'
[    0.000000] x86/fpu: Supporting XSAVE feature 0x002: 'SSE registers'
[    0.000000] x86/fpu: Supporting XSAVE feature 0x004: 'AVX registers'
[    0.000000] x86/fpu: xstate_offset[2]:  576, xstate_sizes[2]:  256
[    0.000000] x86/fpu: Enabled xstate features 0x7, context size is 832 bytes, using 'compacted' format.
[    0.000000] BIOS-provided physical RAM map:
[    0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009ffff] usable
[    0.000000] BIOS-e820: [mem 0x0000000000100000-0x00000000bffaffff] usable
[    0.000000] BIOS-e820: [mem 0x00000000bfc00000-0x00000000bfffffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000c0000000-0x00000000cfffffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0000000-0x00000000d0010fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0011000-0x00000000d0011fff] ACPI data
[    0.000000] BIOS-e820: [mem 0x00000000d0012000-0x00000000d0012fff] ACPI NVS
[    0.000000] BIOS-e820: [mem 0x00000000d0013000-0x00000000d0013fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0014000-0x00000000d0014fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0015000-0x00000000d0015fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0016000-0x00000000d0016fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0017000-0x00000000d0017fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0018000-0x00000000d0018fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0019000-0x00000000d0019fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d001a000-0x00000000d001afff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d001b000-0x00000000d001bfff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d001c000-0x00000000d001cfff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d001d000-0x00000000d001dfff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d001e000-0x00000000d001efff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d001f000-0x00000000d001ffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0020000-0x00000000d0020fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0021000-0x00000000d0021fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0022000-0x00000000d0022fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0023000-0x00000000d0023fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0024000-0x00000000d0024fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0025000-0x00000000d0025fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0026000-0x00000000d0026fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0027000-0x00000000d0027fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0028000-0x00000000d0028fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0029000-0x00000000d0029fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d002a000-0x00000000d002afff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d002b000-0x00000000d002bfff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d002c000-0x00000000d002cfff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d002d000-0x00000000d002dfff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d002e000-0x00000000d002efff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d002f000-0x00000000d002ffff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0030000-0x00000000d0030fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0031000-0x00000000d0031fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0032000-0x00000000d0032fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0033000-0x00000000d0033fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0034000-0x00000000d0034fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0035000-0x00000000d0035fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0036000-0x00000000d0036fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0037000-0x00000000d0037fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0038000-0x00000000d0038fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d0039000-0x00000000d0039fff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d003a000-0x00000000d003afff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d003b000-0x00000000d003bfff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d003c000-0x00000000d003cfff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d003d000-0x00000000d003dfff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d003e000-0x00000000d003efff] reserved
[    0.000000] BIOS-e820: [mem 0x00000000d003f000-0x00000000d003ffff] reserved
[    0.00000

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