[Buildroot] Remote debug

[Peter Seiderer]

Hello Andrew,

On Fri, 25 Jan 2019 13:50:01 +0000, Andrew <andrewtholt60 at gmail.com> wrote:

> Hi,
> 
> I’m have a problem remotely debugging a device.
> 
> My setup is
> 
> Target: Boundary Devices Nitrogen 6 (i.MX6)
> 
> Host : Linux Mint 18.3 Sylvia
> 
> Buildroot 2017.08
> 
> I have built my image so that if I run file on a binary I get this:
> 
> file /usr/bin/lwsws
> /usr/bin/lwsws: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), 
> dynamically linked, interpreter /lib/ld-linux-armhf.so.3, for GNU/Linux 
> 2.6.32, BuildID[sha1]=04bcb93a38c3a59d7ec2812a70c4e13fd5609024, with 
> debug_info, not stripped

Which compiler debug flags did your use compiling/linking your executable?

Try with an simple hello world and '-g' flag...or paste your compile/link
commands....or re-build your executable and check for '-g' flag...

> 
> If I run gdbserver on the target I can connect from the host, set a 
> breakpoint on a symbol (e.g. main) run the code, and the breakpoint is 
> hit and the code stops.
> 
> If I try to list the code, I simply get the gdb prompt. If I try to list 
> the code
> 
> So here is waht I see on the host
> 
> |$GDB -x ~/.gdbinit GNU gdb (Linaro_GDB-2017.02) 7.12.1.20170215-git 
> Copyright (C) 2017 Free Software Foundation, Inc. License GPLv3+: GNU 
> GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free 
> software: you are free to change and redistribute it. There is NO 
> WARRANTY, to the extent permitted by law. Type "show copying" and "show 
> warranty" for details. This GDB was configured as 
> "--host=x86_64-unknown-linux-gnu --target=arm-linux-gnueabihf". Type 
> "show configuration" for configuration details. For bug reporting 
> instructions, please see: <http://www.gnu.org/software/gdb/bugs/>. Find 
> the GDB manual and other documentation resources online at: 
> <http://www.gnu.org/software/gdb/documentation/>. For help, type "help". 
> Type "apropos word" to search for commands related to "word". (gdb) set 
> remote exec-file lwsws (gdb) target remote 10.31.1.113:2345 
> ^C10.31.1.113:2345: Interrupted system call. (gdb) Quit (gdb) target 
> remote 10.31.1.99:2345 Remote debugging using 10.31.1.99:2345 Reading 
> /usr/bin/lwsws from remote target... warning: File transfers from remote 
> targets can be slow. Use "set sysroot" to access files locally instead. 
> Reading /usr/bin/lwsws from remote target... Reading symbols from 
> target:/usr/bin/lwsws...done. Reading /lib/ld-linux-armhf.so.3 from 
> remote target... Reading /lib/ld-linux-armhf.so.3 from remote target... 
> Reading symbols from target:/lib/ld-linux-armhf.so.3...(no debugging 
> symbols found)...done. 0x76fd7a00 in _start () from 
> target:/lib/ld-linux-armhf.so.3 (gdb) br main Breakpoint 1 at 0x10f3c 
> (gdb) run The "remote" target does not support "run". Try "help target" 
> or "continue". (gdb) c Continuing. Reading /usr/lib/libwebsockets.so.12 
> from remote target... Reading /usr/lib/libz.so.1 from remote target... 
> Reading /usr/lib/libssl.so.1.0.0 from remote target... Reading 
> /usr/lib/libcrypto.so.1.0.0 from remote target... Reading 
> /usr/lib/libuv.so.1 from remote target... Reading /lib/libm.so.6 from 
> remote target... Reading /lib/libc.so.6 from remote target... Reading 
> /lib/libdl.so.2 from remote target... Reading /lib/librt.so.1 from 
> remote target... Reading /lib/libpthread.so.0 from remote target... 
> Reading /lib/libnsl.so.1 from remote target... Breakpoint 1, 0x00010f3c 
> in main () (gdb) |
> 
> So, if I now do:
> 
> l main
> 
> I get
> 
> (gdb)
> 
> Any hint tips, questions much appreciated.

Rebuild your buildroot project with BR2_ENABLE_DEBUG=y

Use 'set sysroot' as suggested in your gdb trace

	(gdb) set sysroot some_buildroot_build_patch/host/arm-buildroot-linux-gnueabihf/sysroot
	(gdb) target remote 10.31.1.113:2345

Additional suggestions

- enable BR2_PACKAGE_HOST_GDB and use the generated gdb instead
the one from your toolchain?

Regards,
Peter

> 
> Andrew
> 
> ​