RFR: Make Serviceability Agent attach functionality optional

[Mikael Vidstedt]

> On Apr 18, 2017, at 4:12 AM, Erik Joelsson <erik.joelsson at oracle.com> wrote:
> 
> I would prefer this construct in Lib-jdk.hotspot.agent.gmk to avoid duplication:
> 
> SA_LIBS := $(LIBDL)
> ifeq ($(INCLUDE_SA_ATTACH), true)
>  SA_LIBS += -lthread_db
> endif

I meant to do that before pushing, thanks for the catch. Fixed.

> I agree with using space after comma in the makefiles, we try to do that when possible.

Fixed.

Cheers,
Mikael

> 
> /Erik
> 
> On 2017-04-14 01:36, Mikael Vidstedt wrote:
>> Here’s an ugly incremental fix to get things building again:
>> 
>> hotspot: http://cr.openjdk.java.net/~mikael/webrevs/portola/attachfix/webrev.00/hotspot/webrev/
>> 
>> I’m going to file an enhancement to follow up on this to see if it can be cleaned up. Meanwhile, please have a look at the changes - both the ones I send out earlier, and the above fix.
>> 
>> Cheers,
>> Mikael
>> 
>>> On Apr 13, 2017, at 3:31 PM, Mikael Vidstedt <mikael.vidstedt at oracle.com> wrote:
>>> 
>>> 
>>> FYI: I messed up the details of the patch. Working on fixing it.
>>> 
>>> Cheers,
>>> Mikael
>>> 
>>>> On Apr 13, 2017, at 9:19 AM, Mikael Vidstedt <mikael.vidstedt at oracle.com> wrote:
>>>> 
>>>> 
>>>> The Serviceability Agent (aka. SA) has functionality to attach to running processes forcefully/without the cooperation of the VM, allowing “live” debugging even when the processes is stuck. On linux the implementation relies on the functionality provided by the thread_db.h header file.
>>>> 
>>>> musl doesn’t support thread_db.h (or any other thread debugging library for that sake). This patch makes the inclusion of the attach/live debugging support optional, and only includes it if the thread_db.h header file is available.
>>>> 
>>>> Note that the core debugging functionality still works without the attach/live debugging functionality in the SA (at least in theory, I haven’t taken core debugging for a spin yet).
>>>> 
>>>> top: http://cr.openjdk.java.net/~mikael/webrevs/portola/sathreaddb/webrev.00/webrev/
>>>> hotspot: http://cr.openjdk.java.net/~mikael/webrevs/portola/sathreaddb/webrev.00/hotspot/webrev/
>>>> 
>>>> Cheers,
>>>> Mikael
>>>> 
>