Question

我正在使用Minnowboard Max和使用u-boot定制的Linux内核的嵌入式项目。

内核命令行参数：

initcall_debug=1 video=HDMI-A-1:1920x1200MR@60D console=ttyS0,115200 console=tty0

我发现misc.c文件中定义的debug_pustr消息都没有打印在串口中。

debug_putstr("\nDecompressing Linux... ");

我也启用了内核menuconfig中的CONFIG_X86_VERBOSE_BOOTUP =y。

有没有办法在串口中看到这些消息？

Answer 1

有没有办法在串口中看到这些消息？

显着的信息是处理器架构例如，在ARM引导中，解压缩器代码使用其自己的串行端口配置，这与earlyprintk不同。有些ARM机器有配置对话框来指定这个早期的串口;有些人可能会使用机器ID（参见How do I find ARM Linux entry point when it fails to uncompress?）。在早期（init / main.c） init_kernel（）例程启动后，在早期的ARM中，earlyprintk无效。

对于x86所有早期串口配置＆amp; I / O被合并到earlyprintk功能中。使用kernel命令行参数定义串口（默认设备为0x3F8）和波特率（默认为9600）。

1081         earlyprintk=    [X86,SH,BLACKFIN,ARM,M68k]
1082                         earlyprintk=vga
1083                         earlyprintk=efi
1084                         earlyprintk=xen
1085                         earlyprintk=serial[,ttySn[,baudrate]]
1086                         earlyprintk=serial[,0x...[,baudrate]]
1087                         earlyprintk=ttySn[,baudrate]
1088                         earlyprintk=dbgp[debugController#]
1089                         earlyprintk=pciserial,bus:device.function[,baudrate]
1090 
1091                         earlyprintk is useful when the kernel crashes before
1092                         the normal console is initialized. It is not enabled by
1093                         default because it has some cosmetic problems.
1094 
1095                         Append ",keep" to not disable it when the real console
1096                         takes over.
1097 
1098                         Only one of vga, efi, serial, or usb debug port can
1099                         be used at a time.
1100 
1101                         Currently only ttyS0 and ttyS1 may be specified by
1102                         name.  Other I/O ports may be explicitly specified
1103                         on some architectures (x86 and arm at least) by
1104                         replacing ttySn with an I/O port address, like this:
1105                                 earlyprintk=serial,0x1008,115200
1106                         You can find the port for a given device in
1107                         /proc/tty/driver/serial:
1108                                 2: uart:ST16650V2 port:00001008 irq:18 ...
1109 
1110                         Interaction with the standard serial driver is not
1111                         very good.
1112 
1113                         The VGA and EFI output is eventually overwritten by
1114                         the real console.
1115 
1116                         The xen output can only be used by Xen PV guests.

Linux内核解压缩Linux消息未在UART上打印

1 个答案: