Request for review 7191817: -XX:+UseSerialGC -XX:+UseLargePages crashes with SIGFPE on Mac OS X

[Daniel D. Daugherty]

On 10/25/12 1:14 AM, Staffan Larsen wrote:
> On 25 okt 2012, at 05:39, David Holmes<David.Holmes at oracle.com>  wrote:
>
>> Hi Harold,
>>
>> My only query is whether _ALLBSD_SOURCE is the right conditional for this? Exactly which platform(s) don't support this?
>>
>> The reason I ask is that even the BSD sources (eg ./os/bsd/vm/os_bsd.hpp) contain ifdefs for _ALL_BSD_SOURCE which indicates that some bsd builds do not in fact set _ALLBSD_SOURCE ! Which I find extremely confusing.
> I actually think this is just leftovers from the port and should be removed. I think when the port to bsd was made, we started with the linux code and then added these ifdefs to show what the "orginal" code looked like while working on the new code. I may be wrong here and someone maybe has a better explanation. The code that is ifdef:ed away looks very similar to the linux code.
>
> I have a patch somewhere to remove this code, but I haven't gotten around to finish it up.
>
> /Staffan

Staffan is correct. _ALL_BSD_SOURCE was indeed used to distinguish
between the original Linux code and the changes specific to BSD.
I left them in because it made it easier to re-audit the changes
during the many resyncs with the bsd-port and macosx-port projects.

If we ever get around to putting all the common UNIXish code in one
place, then this kind of stuff can go away... Hey maybe the logical
platform can be "COMMIX/commix" :-)

Dan


>> Thanks,
>> David
>>
>> On 25/10/2012 12:22 AM, harold seigel wrote:
>>> Please review this updated webrev:
>>> http://cr.openjdk.java.net/~coleenp/bug_7191817_2/
>>> <http://cr.openjdk.java.net/%7Ecoleenp/bug_7191817_2/>
>>>
>>> It incorporates Dave's suggestion to use the UNSUPPORTED_OPTION macro.
>>>
>>> Thanks, Harold
>>>
>>> On 10/24/2012 5:46 AM, David Holmes wrote:
>>>> Hi Harold,
>>>>
>>>> We already have a macro for this:
>>>>
>>>> // Disable options not supported in this release, with a warning if they
>>>> // were explicitly requested on the command-line
>>>> #define UNSUPPORTED_OPTION(opt, description) \
>>>> do { \
>>>> if (opt) { \
>>>> if (FLAG_IS_CMDLINE(opt)) { \
>>>> warning(description " is disabled in this release."); \
>>>> } \
>>>> FLAG_SET_DEFAULT(opt, false); \
>>>> } \
>>>> } while(0)
>>>>
>>>> We use this on platforms were not all features are supported.
>>>>
>>>> David
>>>>
>>>> On 24/10/2012 5:04 AM, harold seigel wrote:
>>>>> Summary: Support for the -XX:+UseLargePages flag causes crashes on BSD
>>>>> platforms such as MacOS X. This proposed change adds code to print out a
>>>>> message if -XX:+UseLargePages is specified on this platform and to then
>>>>> ignore the flag.
>>>>>
>>>>> Open webrev at http://cr.openjdk.java.net/~coleenp/bug_7191817
>>>>> <http://cr.openjdk.java.net/%7Ecoleenp/bug_7191817>
>>>>>
>>>>> Bug link at http://bugs.sun.com/view_bug.do?bug_id=7191817
>>>>>
>>>>> This change was tested with JPRT and JCK tests. Also, tests were run by
>>>>> hand on a MacOS X machine specifying the -XX:+UseLargePages flag to make
>>>>> sure that the message was output and no crashes occurred.
>>>>>
>>>>> Thanks, Harold