Re: [PATCH v3] Introduce remote_target_is_gdbserver

[Simon Marchi <simon.marchi@ericsson.com>]

On 14-09-11 11:56 AM, Doug Evans wrote:
> Simon Marchi <simon.marchi@ericsson.com> writes:
>> This patch introduces a function in gdbserver-support.exp to find out
>> whether the current target is GDBserver.
>>
>> The code was inspired from gdb.trace/qtor.exp, so it replaces the code
>> there by a call to the new function.
>>
>> New in v3:
>> - Remove useless "pass" in remote_target_is_gdbserver.
>> - Coding style in qtro.exp (braces in condition).
>> - Changelog entry about qtro.exp.
>>
>> gdb/testsuite/ChangeLog:
>>
>> 	* gdb.trace/qtro.exp: Replace gdbserver detection code by...
>> 	* lib/gdbserver-support.exp (remote_target_is_gdbserver): New
>> 	function.
>> ---
>>  gdb/testsuite/gdb.trace/qtro.exp        | 14 +-------------
>>  gdb/testsuite/lib/gdbserver-support.exp | 18 ++++++++++++++++++
>>  2 files changed, 19 insertions(+), 13 deletions(-)
>>
>> diff --git a/gdb/testsuite/gdb.trace/qtro.exp b/gdb/testsuite/gdb.trace/qtro.exp
>> index 22b5051..700c157 100644
>> --- a/gdb/testsuite/gdb.trace/qtro.exp
>> +++ b/gdb/testsuite/gdb.trace/qtro.exp
>> @@ -98,19 +98,7 @@ if { $traceframe_info_supported == -1 } {
>>  }
>>  
>>  # Check whether we're testing with our own GDBserver.
>> -set is_gdbserver -1
>> -set test "probe for GDBserver"
>> -gdb_test_multiple "monitor help" $test {
>> -    -re "The following monitor commands are supported.*debug-hw-points.*remote-debug.*GDBserver.*$gdb_prompt $" {
>> -	set is_gdbserver 1
>> -	pass $test
>> -    }
>> -    -re "$gdb_prompt $" {
>> -	set is_gdbserver 0
>> -	pass $test
>> -    }
>> -}
>> -if { $is_gdbserver == -1 } {
>> +if { ![remote_target_is_gdbserver] } {
>>      return -1
>>  }
>>  
>> diff --git a/gdb/testsuite/lib/gdbserver-support.exp b/gdb/testsuite/lib/gdbserver-support.exp
>> index 026a937..423c729 100644
>> --- a/gdb/testsuite/lib/gdbserver-support.exp
>> +++ b/gdb/testsuite/lib/gdbserver-support.exp
>> @@ -436,3 +436,21 @@ proc mi_gdbserver_start_multi { } {
>>  
>>      return [mi_gdb_target_cmd $gdbserver_protocol $gdbserver_gdbport]
>>  }
>> +
>> +# Return true if the current remote target is an instance of gdbserver.
>> +
>> +proc remote_target_is_gdbserver { } {
>> +    global gdb_prompt
>> +
>> +    set is_gdbserver 0
>> +    set test "Probing for GDBserver"
>> +
>> +    gdb_test_multiple "monitor help" $test {
>> +	-re "The following monitor commands are supported.*Quit GDBserver.*$gdb_prompt $" {
>> +		set is_gdbserver 1
>> +	}
>> +	-re "$gdb_prompt $" {
>> +	}
>> +    }
>> +    return $is_gdbserver
>> +}
> 
> Hi.
> 
> The original code allowed for a -1 value of is_gdbserver
> to handle the case of "can't tell" (e.g. for a timeout or
> whatever, IIUC).
> While IWBN to not complicate the API of
> remote_target_is_gdbserver by requiring the caller
> to have to handle this, maybe it'd be best if the caller
> did have to watch for -1 and not just assume "not gdbserver":
> maybe a different test will want to handle all three cases
> (can't-tell, no, or yes).
> E.g., initialize is_gdbserver to -1, and watch for a -1 value
> before returning.
> 
> proc remote_target_is_gdbserver { } {
>     global gdb_prompt
> 
>     set is_gdbserver -1
>     set test "Probing for GDBserver"
> 
>     gdb_test_multiple "monitor help" $test {
> 	-re "The following monitor commands are supported.*Quit GDBserver.*$gdb_prompt $" {
> 	    set is_gdbserver 1
> 	}
> 	-re "$gdb_prompt $" {
> 	    set is_gdbserver 0
> 	}
>     }
>     if { $is_gdbserver == -1 } {
> 	verbose -log "can't tell if using gdbserver or not" # or whatever
> 	set $is_gdbserver 0  # <<<< this part I'm not sure about
>     }
>     return $is_gdbserver

I am confused. Do you want remote_target_is_gdbserver to return -1 in case of error, or not. The paragraph seems to say yes, but the code seems to say no.

> Also, I see an earlier version of the patch first
> did a check for [is_remote_target] before calling
> target_is_gdbserver, and the new version of the
> patch changes that to just calling remote_target_is_gdbserver.
> Since the function remote_target_is_gdbserver can
> be used regardless of whether the target is remote,
> let's remove "remote_" from the name.
> ie., go back to target_is_gdbserver.

Indeed, if the name is target_is_gdbserver, it would be clearer that you can call it in any situation, even if you are using native.

However, in that particular case, I removed the [is_remote target] check, since there is an equivalent one earlier in the test.

> Hmmm, another thought.
> Since this requires an exchange with the target,
> IWBN to cache the result.
> There's support for doing this in the harness,
> grep for gdb_caching_proc.

Interesting, I will check that.