[patch] Suggest newer gdbserver if it has no qXfer:exec-file:read

[Pedro Alves]

On 03/19/2016 08:18 PM, Jan Kratochvil wrote:
> Hi,
>
> currently:
> 	$ gdbserver-7.9 :1234 true &
> 	$ gdb -q -ex 'target remote :1234' # that -q is not relevant here
> 	Remote debugging using :1234
> 	warning: Could not load vsyscall page because no executable was specified
> 	try using the "file" command first.
> 	0x00007ffff7ddcc80 in ?? ()
> 	(gdb) b main
> 	No symbol table is loaded.  Use the "file" command.
> 	Make breakpoint pending on future shared library load? (y or [n]) _
>
> While one may not realize a newer gdbserver would fix that:
> 	$ gdbserver-7.10 :1234 true &
> 	$ gdb -q -ex 'target remote :1234' # that -q is not relevant here
> 	Remote debugging using :1234
> 	Reading /usr/bin/true from remote target...
> 	warning: File transfers from remote targets can be slow. Use "set sysroot" to access files locally instead.
> 	Reading /usr/bin/true from remote target...
> 	Reading symbols from target:/usr/bin/true...Reading symbols from /usr/lib/debug/usr/bin/true.debug...done.
> 	done.
> 	Reading /lib64/ld-linux-x86-64.so.2 from remote target...
> 	Reading /lib64/ld-linux-x86-64.so.2 from remote target...
> 	Reading symbols from target:/lib64/ld-linux-x86-64.so.2...Reading symbols from /usr/lib/debug/usr/lib64/ld-2.22.so.debug...done.
> 	done.
> 	0x00007ffff7ddcc80 in _start () from target:/lib64/ld-linux-x86-64.so.2
> 	(gdb) b main
> 	Breakpoint 1 at 0x555555555650: file src/true.c, line 59.
> 	(gdb) _
>
> This can be more common case with the popular containers.  Therefore
> suggesting to print there also:
> 	warning: No executable has been specified (see the "file" command) and remote gdbserver does not support packet "qXfer:exec-file:read" - please use FSF gdbserver version 7.10 or later.
>
> OK for check-in?
>
> No regressions on {x86_64,x86_64-m32,i686}-fedora23-linux-gnu.
>
> The "qXfer:exec-file:read" support in GDB and gdbserver was implemented by:
> 	commit c78fa86a213db1bdef328437ac262a4f54577827
> 	Author: Gary Benson<gbenson@redhat.com>
> 	Date:   Fri Apr 17 09:47:30 2015 +0100
> 	    Implement remote_pid_to_exec_file using qXfer:exec-file:read
>
>
> Thanks,
> Jan
>
>
> gdbexec.patch
>
>
> gdb/ChangeLog
> 2016-03-19  Jan Kratochvil<jan.kratochvil@redhat.com>
>
> 	* remote.c (remote_pid_to_exec_file): Print warning for unsupported
> 	PACKET_qXfer_exec_file.
>
> diff --git a/gdb/remote.c b/gdb/remote.c
> index af0a08a..d267736 100644
> --- a/gdb/remote.c
> +++ b/gdb/remote.c
> @@ -12977,7 +12977,13 @@ remote_pid_to_exec_file (struct target_ops *self, int pid)
>     char *annex = NULL;
>
>     if (packet_support (PACKET_qXfer_exec_file) != PACKET_ENABLE)
> -    return NULL;
> +    {
> +      warning (_("No executable has been specified (see the \"file\" command) "
> +                 "and remote gdbserver does not "
> +		 "support packet \"qXfer:exec-file:read\""
> +		 " - please use FSF gdbserver version 7.10 or later."));
> +      return NULL;
> +    }

I think this will print the warning after connecting to any
random stub, not just gdbserver.  Won't it be confusing
to suggest FSF gdbserver in that case?

Thanks,
Pedro Alves