KGDB on i.MX8 serial polling function

lorenzo_giraudi — Fri, 27 Nov 2020 13:30:12 GMT

Hello,

I am trying to debug the Linux Kernel remotely using KGDB over the serial port.

I followed the instruction shown here: https://elinux.org/images/1/1b/ELC19_Serial_kdb_kgdb.pdf but can't make it to work. This is what I get:

I can do echo ttyLP0 > /sys/module/kgdboc/parameters/kgdboc and it gets successfully registered (note: ttyLP0 is my console too)
when I do echo g > /proc/sysrq-trigger I get messages telling that the kernel dropped into kdb, then I see the kdb prompt but it stops there, when I try to type nothing happens

I have the idea that it may involve the polling functions lpuart32_poll_put_char and lpuart32_poll_get_char but I do not know how to debug it.

It would be great to know if someone from NXP ever tried it.

BR,

Lorenzo

Re: KGDB on i.MX8 serial polling function

igorpadykov — Sun, 29 Nov 2020 00:55:25 GMT

Hi Lorenzo

one can look at Uboot/Kernel/SCFW debugging documentation AN12631

Best regards
igor