Uboot and kernel modify and print the serial port and ubootkernel serial port

Uboot and kernel modify and print the serial port and ubootkernel serial port

Here I use s5pv210, which originally outputs COM2. Now I want to change it to COM0 output, to view the uboot command line information and the kernel startup information, we should make the following changes:

1. Changes to uboot

We modify the corresponding configuration file. Here, because it is s5pv210 Development Board, my configuration file is x210_sd.h (9ding Development Board)

Find

//#define CONFIG_SERIAL3          1/* we use UART2 on SMDKC110 */

Change

#define CONFIG_SERIAL0          1/* we use UART0 on SMDKC110 */

Cause: Find this string in the register definition file of our corresponding Development Board: (I am here at s5pc110. h)

#if defined(CONFIG_SERIAL1)#define ELFIN_UART_CONSOLE_BASE (ELFIN_UART_BASE + ELFIN_UART0_OFFSET)#elif defined(CONFIG_SERIAL2)#define ELFIN_UART_CONSOLE_BASE (ELFIN_UART_BASE + ELFIN_UART1_OFFSET)#elif defined(CONFIG_SERIAL3)#define ELFIN_UART_CONSOLE_BASE (ELFIN_UART_BASE + ELFIN_UART2_OFFSET)#elif defined(CONFIG_SERIAL4)#define ELFIN_UART_CONSOLE_BASE (ELFIN_UART_BASE + ELFIN_UART3_OFFSET)#else#define ELFIN_UART_CONSOLE_BASE (ELFIN_UART_BASE + ELFIN_UART0_OFFSET)#endif

Therefore, we only need to define the corresponding CONFIG_SERIAL to make the modification successful.

2. Modify linux kernel (the premise here is that you find the. config file in ls-)

First, make menuconfig

System Type  --->    (2) S3C UART to use for low-level messages 

Modify

System Type  --->    (0) S3C UART to use for low-level messages 

Then make-j4 (multi-thread kernel compilation)

3. Modify the tags parameter passed by uboot to linux kernel

Enter the uboot command line and print the information

mtdpart=80000 400000 3000000baudrate=115200ethaddr=00:40:5c:26:0a:5bbootdelay=3filesize=37B800fileaddr=30008000gatewayip=192.168.0.1netmask=255.255.255.0ipaddr=192.168.0.120serverip=192.168.0.119bootcmd=tftp 30008000 zImage-qt; bootm 30008000bootargs=console=ttySAC2,115200 root=/dev/mmcblk0p2 rw init=/linuxrc rootfstype=ext3

Here, we can change console = ttySAC2 in bootargs to ttySAC0.

set 'console=ttySAC0,115200 root=/dev/mmcblk0p2 rw init=/linuxrc rootfstype=ext3'save

Now, we have modified the serial port printing information of uboot and kernel.