Re: [PATCH] Check if /proc is usable on gdbserver start

[Vyacheslav Barinov <v.barinov@samsung.com>]

Pedro Alves <palves@redhat.com> writes:
> On 07/04/2018 08:34 AM, Vyacheslav Barinov wrote:
>> Hello,
>> 
>> Just lost a couple of hours trying to find while gdb can't connect to gdbserver
>> in my debug session.
>> 
>> There's a buildroot where I want to debug a binary, and I tried to connect to
>> it from outside, but got very weird errors like architecture mismatch or
>> protocol errors. At last, after switching on '--debug' for gdbserver I found a
>> message 'Can't open /proc/pid/' message and suddenly found that I forgot to
>> mount procfs in my buildroot.
>> 
>> I think it's better to check this before running gdbserver.
> I'm not certain that it's a good idea to absolute require a /proc mount.
> Even though we gradually moved into relying on /proc more (or better said, on
> libthread_db less), over the years we've also tried to be tolerant to
> missing /proc.  I believe people had use cases for that (very constrained
> containers or embedded systems?  I don't recall exactly though...)
>
> I assume that you're on either Aarch64 or x86_64 and that the architecture
> mismatch is because gdbserver couldn't determine whether the process
> was a 64-bit process, because that is done by reading the /proc/PID/exe
> file.  Maybe other 32-bit- or 64-bit-only archs still minimally work
> without /proc.
>
> I'm thinking that it may be prudent to downgrade this to a warning.
> Would that work for you?
>
> Thanks,
> Pedro Alves
You are right, I use x86_64 architecture.

Okay, if the gdbserver can work without /proc, then just warning for cases
like this is enough.

Best Regards,
Vyacheslav Barinov