2009-09-24 08:34:45 Problem with kgdb over UART

Manu AS (INDIA)

Message: 80375

Hi,

I have enabled kgdb over UART. I have used the following steps:

1. Applied the kgdb patch. Selected the following options thru make menuconfig

"Kernel hacking" -> "Kernel debugging" -> "KGDB: kernel debug with remote gdb".

With this selected, option "Full Symbolic/Source Debugging support" and

"Compile the kernel with frame pointers" are also selected.

2. Select option "KGDB: connect over UART". Set "KGDB: UART port number" to console.

Changed the mode of blackfin serial driver to PIO.

3. Connected minicom to the serial port and boot the kernel image.

4. Start GDB client "bfin-elf-gdb vmlinux".

5. Set the baud rate in GDB "(gdb) set remotebaud 9600".

6. Connect to the target "(gdb) target remote /dev/ttyS0".

7. Set software breakpoint "(gdb) break sys_open".

8. Continue "(gdb) c".

I can set the breakpoints and continue the execution.

Now to stop the gdb connection and run the "/> ls" command on the serial console, I tried pressing 'Ctrl+C' 2 times in minicom as mentioned in the document. The gdb connection is stopped but, I am not able enter anything in the serial console.

Can somebody tell me if I am doing anything wrong?

Thanks in advance.

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2009-09-24 11:00:41 Re: Problem with kgdb over UART

Mike Frysinger (UNITED STATES)

Message: 80387

if you applied the patch, it means you're using an old release. perhaps it's time to upgrade.

you didnt say exactly what hardware you're using or what ports you're connecting things to. you shouldnt use the same serial port for both kgdb and a serial console. while it is possible to make things work if you know exactly what you're doing and exactly how the system is working, it's easier to simply use a dedicated serial port for kgdb.

breaking into kgdb via ctrl+c doesnt work very well when connecting via the uart.

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2009-09-25 01:16:14 Re: Problem with kgdb over UART

Manu AS (INDIA)

Message: 80414

I am using 2008R1. Last week I used the same distribution with the kgdb patch to enable kgdb over ethernet. And it is working. Our team needs kgdb over UART also. So, I am trying this.

I am using BF561 based board, and the board has single UART port (/dev/ttyS0).

So, you mean to say, to effectively debug kernel using UART, we should have 2 UART ports (one for kgdb and one for console)?

Is there any way I can make it work with the above info?

Thanks.

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2009-09-25 02:06:39 Re: Problem with kgdb over UART

Sonic Zhang (CHINA)

Message: 80416

Disable your console on the only UART.

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2009-09-25 04:44:08 Re: Problem with kgdb over UART

Manu AS (INDIA)

Message: 80444

I tried disabling console on the UART. But no luck.

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2009-09-25 04:59:47 Re: Problem with kgdb over UART

Sonic Zhang (CHINA)

Message: 80445

We run kgdb over UART without problem if the console is not on the same uart port.

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2009-09-28 11:41:37 Re: Problem with kgdb over UART

Manu AS (INDIA)

Message: 80569

I am using bf561 based board, which has 1 UART port and 2 SPORTs. I want to use one of the SPORT to emulate UART, so that I can have a dedicated UART for kgdb and one for console.

Can some body tell me how to configure an SPORT as a UART port?

Thanks

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2009-09-28 11:48:02 Re: Problem with kgdb over UART

Robin Getz (UNITED STATES)

Message: 80570

Manu:

https://docs.blackfin.uclinux.org/doku.php?id=linux-kernel:drivers:bfin_sport_uart

-Robin

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2009-10-15 07:00:35 Re: Problem with kgdb over UART

pham manh tuan (VIET NAM)