首页/资讯中心/详情

Linux 内核启动日志输出阶段分析

Linux 内核启动日志输出阶段分析
📅 发布时间：2026/6/19 9:58:06

问题描述

在对比原理图后，发现打印日志的串口是UART2(GPIO3_A2 & GPIO3_A3)，但设备树中只开启了UART0(GPIO1_C2&GPIO1_C3)
/* 以下设备树内容来自多个设备树描述文件*/

&uart0 {pinctrl-names = "default";pinctrl-0 = <&uart0_xfer &uart0_ctsn>;status = "okay";
};
uart0: serial@ff560000 {compatible = "rockchip,rv1126-uart", "snps,dw-apb-uart";reg = <0xff560000 0x100>;interrupts = <GIC_SPI 12 IRQ_TYPE_LEVEL_HIGH>;reg-shift = <2>;reg-io-width = <4>;dmas = <&dmac 5>, <&dmac 4>;clock-frequency = <24000000>;clocks = <&cru SCLK_UART0>, <&cru PCLK_UART0>;clock-names = "baudclk", "apb_pclk";pinctrl-names = "default";pinctrl-0 = <&uart0_xfer &uart0_ctsn &uart0_rtsn>;status = "disabled";
};
uart0_xfer: uart0-xfer {rockchip,pins =/* uart0_rx */<1 RK_PC2 1 &pcfg_pull_up>,/* uart0_tx */<1 RK_PC3 1 &pcfg_pull_up>;
};
uart2: serial@ff570000 {compatible = "rockchip,rv1126-uart", "snps,dw-apb-uart";reg = <0xff570000 0x100>;interrupts = <GIC_SPI 14 IRQ_TYPE_LEVEL_HIGH>;reg-shift = <2>;reg-io-width = <4>;dmas = <&dmac 9>, <&dmac 8>;clock-frequency = <24000000>;clocks = <&cru SCLK_UART2>, <&cru PCLK_UART2>;clock-names = "baudclk", "apb_pclk";pinctrl-names = "default";pinctrl-0 = <&uart2m1_xfer>;status = "disabled";
};
uart2m1_xfer: uart2m1-xfer {rockchip,pins =/* uart2_rx_m1 */<3 RK_PA3 1 &pcfg_pull_up>,/* uart2_tx_m1 */<3 RK_PA2 1 &pcfg_pull_up>;
};

问题分析

无论是硬件原理图还是实际结果都表示启动日志是从UART2打印出来的，所以我们就要尽量往UART2去拓展。
由设备树可以得到内核启动参数 bootargs：

chosen {bootargs = "earlycon=uart8250,mmio32,0xff570000 console=ttyFIQ0 root=PARTUUID=614e0000-0000 rootfstype=ext4 rootwait snd_aloop.index=7";
};

earlycon阶段（内核初始化早期）

首先可以看到earlycon=uart8250,mmio32,0xff570000，earlycon直接在设备树解析前初始化硬件，不依赖设备树中的status属性。在内核初始化早期，直接向地址0xff570000输出日志，对比之前提到的设备树配置，我们可以看到这个地址就是UART2串口。

标准console阶段（内核初始化后期）

在bootargs中设置了console=ttyFIQ0

  • 由于UART2在设备树中被标记为disabled,内核不会注册标准UART驱动（如ttyS2）
  • 后续日志会通过ttyFIQ0输出(通常是 Rockchip 的 FIQ 调试串口)
    就像一个知道结果的解谜游戏，我们现在大可以猜测是不是ttyFIQ0配置了UART2，接过了日志输出的任务并继续向UART2输出（通过FIQ驱动，绕过标准UART状态），接下来我们继续分析设备树：
&fiq_debugger {status = "okay";
};

fiq_debugger是启用的，我们继续向上层设备树文件找，目前来到了rv1126.dtsi

fiq_debugger: fiq-debugger {compatible = "rockchip,fiq-debugger";rockchip,serial-id = <2>;  // 绑定到 UART2rockchip,wake-irq = <0>;rockchip,irq-mode-enable = <0>;rockchip,baudrate = <1500000>;  /* Only 115200 and 1500000 */interrupts = <GIC_SPI 127 IRQ_TYPE_LEVEL_HIGH>;status = "disabled";
};

出现了！rockchip,serial-id = <2>,我们可以看到fiq_debugger节点绑定到了UART2，由此完成了内核启动早期与后期的日志输出的衔接。

总结

本篇文章是由一个status为disable但却被作为日志输出的UART2引出，核心是围绕着bootargs中的earlycon与console参数展开。earlycon直接通过UART2的地址，在设备树解析前输出早期日志；console通过FIQ调试串口，复用了UART2的端口，实际上是使用了FIQ的驱动输出后续日志。完成了整个内核初始化及后续过程中的日志输出不同阶段的衔接。

 

 

 


weibo.com/ttarticle/p/show?id=2309405230493322313957
weibo.com/ttarticle/p/show?id=2309405230493368189028
weibo.com/ttarticle/p/show?id=2309405230493406199835
weibo.com/ttarticle/p/show?id=2309405230493422714951
weibo.com/ttarticle/p/show?id=2309405230493443686418
weibo.com/ttarticle/p/show?id=2309405230493460725989
weibo.com/ttarticle/p/show?id=2309405230493477503078
weibo.com/ttarticle/p/show?id=2309405230493523378401
weibo.com/ttarticle/p/show?id=2309405230493565321440
weibo.com/ttarticle/p/show?id=2309405230493573972182
weibo.com/ttarticle/p/show?id=2309405230493594943629
weibo.com/ttarticle/p/show?id=2309405230493611458688
weibo.com/ttarticle/p/show?id=2309405230493628235780
weibo.com/ttarticle/p/show?id=2309405230493728899303
weibo.com/ttarticle/p/show?id=2309405230493766910080
weibo.com/ttarticle/p/show?id=2309405230493762453712
weibo.com/ttarticle/p/show?id=2309405230493779492981
weibo.com/ttarticle/p/show?id=2309405230493892476943
weibo.com/ttarticle/p/show?id=2309405230493921837414
weibo.com/ttarticle/p/show?id=2309405230493934419978
weibo.com/ttarticle/p/show?id=2309405230493930488005
weibo.com/ttarticle/p/show?id=2309405230494047666256
weibo.com/ttarticle/p/show?id=2309405230494077026508
weibo.com/ttarticle/p/show?id=2309405230494081220789
weibo.com/ttarticle/p/show?id=2309405230494085415090
weibo.com/ttarticle/p/show?id=2309405230495448825928
weibo.com/ttarticle/p/show?id=2309405230495473729934
weibo.com/ttarticle/p/show?id=2309405230495478186010
weibo.com/ttarticle/p/show?id=2309405230495566266404
weibo.com/ttarticle/p/show?id=2309405230495599820968
weibo.com/ttarticle/p/show?id=2309405230495662473537
weibo.com/ttarticle/p/show?id=2309405230495671124098
weibo.com/ttarticle/p/show?id=2309405230495733776459
weibo.com/ttarticle/p/show?id=2309405230495750815818
weibo.com/ttarticle/p/show?id=2309405230495813730514
weibo.com/ttarticle/p/show?id=2309405230495817924799
weibo.com/ttarticle/p/show?id=2309405230495838634268
weibo.com/ttarticle/p/show?id=2309405230495910199428
weibo.com/ttarticle/p/show?id=2309405230495964463602
weibo.com/ttarticle/p/show?id=2309405230495973113863
weibo.com/ttarticle/p/show?id=2309405230495994085425
weibo.com/ttarticle/p/show?id=2309405230496057000099
weibo.com/ttarticle/p/show?id=2309405230496119914687
weibo.com/ttarticle/p/show?id=2309405230496136691774
weibo.com/ttarticle/p/show?id=2309405230496216121432
weibo.com/ttarticle/p/show?id=2309405230496270909520
weibo.com/ttarticle/p/show?id=2309405230496300007898
weibo.com/ttarticle/p/show?id=2309405230496363184280
weibo.com/ttarticle/p/show?id=2309405230496371572845
weibo.com/ttarticle/p/show?id=2309405230496417447977
weibo.com/ttarticle/p/show?id=2309405230496459391056
weibo.com/ttarticle/p/show?id=2309405230496518373436
weibo.com/ttarticle/p/show?id=2309405230496522567732
weibo.com/ttarticle/p/show?id=2309405230496530694319
weibo.com/ttarticle/p/show?id=2309405230496568443042
weibo.com/ttarticle/p/show?id=2309405230496673562709
weibo.com/ttarticle/p/show?id=2309405230496686145955
weibo.com/ttarticle/p/show?id=2309405230496698466327
weibo.com/ttarticle/p/show?id=2309405230496715505874
weibo.com/ttarticle/p/show?id=2309405230496732282889
weibo.com/ttarticle/p/show?id=2309405230496828490039
weibo.com/ttarticle/p/show?id=2309405230496841334984
weibo.com/ttarticle/p/show?id=2309405230496862306572
weibo.com/ttarticle/p/show?id=2309405230496874889248
weibo.com/ttarticle/p/show?id=2309405230496908182041
weibo.com/ttarticle/p/show?id=2309405230496983679390
weibo.com/ttarticle/p/show?id=2309405230497029816825
weibo.com/ttarticle/p/show?id=2309405230497063633024
weibo.com/ttarticle/p/show?id=2309405230497134673958
weibo.com/ttarticle/p/show?id=2309405230497185268072
weibo.com/ttarticle/p/show?id=2309405230497214366145
weibo.com/ttarticle/p/show?id=2309405230497268891811
weibo.com/ttarticle/p/show?id=2309405230497281475061
weibo.com/ttarticle/p/show?id=2309405230497327874693
weibo.com/ttarticle/p/show?id=2309405230497336263678
weibo.com/ttarticle/p/show?id=2309405230497365623505
weibo.com/ttarticle/p/show?id=2309405230497428276188
weibo.com/ttarticle/p/show?id=2309405230497436664119
weibo.com/ttarticle/p/show?id=2309405230497499840909
weibo.com/ttarticle/p/show?id=2309405230497512423893
weibo.com/ttarticle/p/show?id=2309405230497592116130
weibo.com/ttarticle/p/show?id=2309405230497617019206
weibo.com/ttarticle/p/show?id=2309405230497751236730
weibo.com/ttarticle/p/show?id=2309405230497768014751
weibo.com/ttarticle/p/show?id=2309405230497789247651
weibo.com/ttarticle/p/show?id=2309405230497814413654
weibo.com/ttarticle/p/show?id=2309405230497910620194
weibo.com/ttarticle/p/show?id=2309405230497931854604
weibo.com/ttarticle/p/show?id=2309405230498061615275
weibo.com/ttarticle/p/show?id=2309405230502042010098
weibo.com/ttarticle/p/show?id=2309405230502092603707
weibo.com/ttarticle/p/show?id=2309405230502167838774
weibo.com/ttarticle/p/show?id=2309405230502235210161
weibo.com/ttarticle/p/show?id=2309405230502247530657
weibo.com/ttarticle/p/show?id=2309405230502318833920
weibo.com/ttarticle/p/show?id=2309405230502390136871
weibo.com/ttarticle/p/show?id=2309405230502390136924
weibo.com/ttarticle/p/show?id=2309405230502440730797
weibo.com/ttarticle/p/show?id=2309405230502512033921
weibo.com/ttarticle/p/show?id=2309405230502549783037
weibo.com/ttarticle/p/show?id=2309405230502549782947
weibo.com/ttarticle/p/show?id=2309405230502704972289
weibo.com/ttarticle/p/show?id=2309405230502729875565
weibo.com/ttarticle/p/show?id=2309405230502750847181
weibo.com/ttarticle/p/show?id=2309405230502868549950
weibo.com/ttarticle/p/show?id=2309405230502935396609
weibo.com/ttarticle/p/show?id=2309405230503120207925
weibo.com/ttarticle/p/show?id=2309405230503174733910
weibo.com/ttarticle/p/show?id=2309405230503233454136
weibo.com/ttarticle/p/show?id=2309405230503246037502
weibo.com/ttarticle/p/show?id=2309405230503355088903
weibo.com/ttarticle/p/show?id=2309405230503405420777
weibo.com/ttarticle/p/show?id=2309405230503543570489
weibo.com/ttarticle/p/show?id=2309405230503560347762
weibo.com/ttarticle/p/show?id=2309405230503573193089
weibo.com/ttarticle/p/show?id=2309405230503711342854
weibo.com/ttarticle/p/show?id=2309405230503723925662
weibo.com/ttarticle/p/show?id=2309405230503832977434
weibo.com/ttarticle/p/show?id=2309405230503900086471
weibo.com/ttarticle/p/show?id=2309405230503916863653
weibo.com/ttarticle/p/show?id=2309405230504038498426
weibo.com/ttarticle/p/show?id=2309405230504051081264
weibo.com/ttarticle/p/show?id=2309405230504218853430
weibo.com/ttarticle/p/show?id=2309405230504353333579
weibo.com/ttarticle/p/show?id=2309405230504374304944
weibo.com/ttarticle/p/show?id=2309405230504407597151
weibo.com/ttarticle/p/show?id=2309405230504415985840
weibo.com/ttarticle/p/show?id=2309405230504546271458
weibo.com/ttarticle/p/show?id=2309405230504587952137
weibo.com/ttarticle/p/show?id=2309405230504680226855
weibo.com/ttarticle/p/show?id=2309405230504747335717
weibo.com/ttarticle/p/show?id=2309405230504801861737
weibo.com/ttarticle/p/show?id=2309405230504999256110
weibo.com/ttarticle/p/show?id=2309405230505003450542
weibo.com/ttarticle/p/show?id=2309405230505145794660
weibo.com/ttarticle/p/show?id=2309405230505175154839
weibo.com/ttarticle/p/show?id=2309405230784427982894
weibo.com/ttarticle/p/show?id=2309405230784625115490
weibo.com/ttarticle/p/show?id=2309405230785140753112
weibo.com/ttarticle/p/show?id=2309405230785296204135
weibo.com/ttarticle/p/show?id=2309405230785468170407
weibo.com/ttarticle/p/show?id=2309405230785623360119
weibo.com/ttarticle/p/show?id=2309405230785778548914
weibo.com/ttarticle/p/show?id=2309405230785937932668
weibo.com/ttarticle/p/show?id=2309405230786097316143
weibo.com/ttarticle/p/show?id=2309405230786252243430
weibo.com/ttarticle/p/show?id=2309405230786407432209
weibo.com/ttarticle/p/show?id=2309405230786562621762
weibo.com/ttarticle/p/show?id=2309405230786717810991
weibo.com/ttarticle/p/show?id=2309405230786877457046
weibo.com/ttarticle/p/show?id=2309405230787028451670
weibo.com/ttarticle/p/show?id=2309405230787523117390
weibo.com/ttarticle/p/show?id=2309405230787674374576