Known bug in remote serial protocol, or something else?

Known bug in remote serial protocol, or something else?

[Juha Aaltonen]

I was trying to debug my "standalone gdbstub" when I encountered a
strange problem.

I loaded a debuggee program and started executing it, and it crashed
in a weird address.
When I disassembled the code (ARMv7 target) I found out that some
instructions were corrupted.
I couldn't figure it out about binary transfer (Looked like UTF-8, but
didn't quite match), so I disabled
the 'X'-command, and the 'M'-command seemed to do even worse - telling
by the debug messages
(set debug serial 1, set debug remote 1).

The gdb client I'm using is gdb-multiarch 7.7.1 on Debian 8 (x86_64) -
the one in the official repo.

I'm happy to supply further info, if it could be of any help -
including the debuggee ELF, but maybe this
mailing list is not the place...

Re: Known bug in remote serial protocol, or something else?

[Paul_Koning]

> On Oct 5, 2015, at 8:39 AM, Juha Aaltonen <turbopultti@gmail.com> wrote:
> 
> I was trying to debug my "standalone gdbstub" when I encountered a
> strange problem.
> 
> I loaded a debuggee program and started executing it, and it crashed
> in a weird address.
> When I disassembled the code (ARMv7 target) I found out that some
> instructions were corrupted.
> I couldn't figure it out about binary transfer (Looked like UTF-8, but
> didn't quite match), so I disabled
> the 'X'-command, and the 'M'-command seemed to do even worse - telling
> by the debug messages
> (set debug serial 1, set debug remote 1).

X sends data as binary, as the name says.  Not UTF-8 -- plain 8 bit binary data.

When reading debug traces, don't get confused by the odd byte order.  Most of the time data numbers come across as little endian hex strings, which makes it rather hard to read addresses (or data) if you aren't careful.

> 
> The gdb client I'm using is gdb-multiarch 7.7.1 on Debian 8 (x86_64) -
> the one in the official repo.
> 
> I'm happy to supply further info, if it could be of any help -
> including the debuggee ELF, but maybe this
> mailing list is not the place...

Please follow the bug reporting procedure mentioned on the GDB webpage.

	paul