HI3520 DEBUG BOARD VIA UART
- Thread starter cdxxxcarvn
- Start date
Make real photo from your board with uart connection.
What's the problem?
No log after starting kernel?
What's the problem?
No log after starting kernel?
They often default the console to some other device, such as /dev/ttyS0[123] or /dev/ttyAMA0[123]
alastairstevenson
Staff member
Interrupt the bootloader and use 'printenv' to show the environment variables.
Sometimes these control the level of detail passed to the serial console from the Linux kernel.
It might be interesting if there is one called 'dh_keyboard'.
Sometimes these control the level of detail passed to the serial console from the Linux kernel.
It might be interesting if there is one called 'dh_keyboard'.
thank you. let me try it. i will respond soon to you. Have you done it on this board and had the same problem?
alastairstevenson
Staff member
In the old days, the Linux console device was always assigned to /dev/ttyS0 (that's 'tty' for teletype, an ancient thing I used way back in the late 1970s) The S is for 'serial', describing the port protocol, and the last character is a zero, meaning the first tty/serial device on the system.
Later changes to the Linux kernel specifically for the HiSilicon chips considered the internal nature of the console/serial ports, and described them as AMA devices instead of 'S'erial. The last character is still a zero, meaning the first AMA port.
Now, that's all for the history lesson.
What hardware / firmware people have done in the last couple of years is attempt to obscure or hide the console serial port, by moving it away from device zero and over to device one or device two. In this way, it does not display the boot log or console i/o on the previously default /dev/ttyS0 or /dev/ttyAMA0 devices.The way to defeat this is to (somehow) interrupt the U-Boot boot sequence, and override the kernel/console startup commands. Specifically, you'd forcibly re-direct the console output to /dev/ttyS0 or if that does not work, then /dev/ttyAMA0.
