RFR(xxs): 8210314: [aix] NMT does not show "Safepoint" memory type

[Lindenmaier, Goetz]

Hi Thomas, 

Thanks for fixing this!
I had given this a try before, but only managed to fix the linux ppc platforms :)

Looks good. 

Best regards,
  Goetz.

> -----Original Message-----
> From: ppc-aix-port-dev <ppc-aix-port-dev-bounces at openjdk.java.net> On
> Behalf Of Thomas Stüfe
> Sent: Montag, 3. September 2018 11:46
> To: Hotspot dev runtime <hotspot-runtime-dev at openjdk.java.net>; ppc-
> aix-port-dev at openjdk.java.net
> Subject: RFR(xxs): 8210314: [aix] NMT does not show "Safepoint" memory
> type
> 
> Hi all,
> 
> may I please have reviews for this small, AIX-only change.
> 
> cr: http://cr.openjdk.java.net/~stuefe/webrevs/8210314-aix-NMT-does-
> not-show-safepoint-memory/webrev.00/webrev/
> 
> bug: https://bugs.openjdk.java.net/browse/JDK-8210314
> 
> On AIX, we have our own initialization for the safepoint mechanism. We
> missed registering the polling page with NMT, which the generic code
> path did. This patch adds that.
> 
> Side note:
> 
> We are different for two reasons. One, on ppc we use per default
> SIGTRAP for safepoint signalling, which can be switched off though.
> Second, on AIX, we cannot use os::reserve_memory() to obtain a polling
> page since that memory may not protectable (if it uses sysV shmat).
> Hence, the AIX specific coding.
> 
> Best Regards, Thomas