RFR (S): 8181785: Remove the experimental ClearFPUAtPark JVM Flag

[Daniel D. Daugherty]

We have removed several experimental options without a CCC/CSR request.
This one is identified as:

experimental(intx, ClearFPUAtPark, 0, "(Unsafe, Unstable)")

Since it is flagged as "Unsafe" and "Unstable" (like one or two I removed
in JDK9), no one should be using it. It will not be noticed or missed.

Dan



On 6/9/17 6:36 AM, Robbin Ehn wrote:
> On 06/09/2017 02:27 PM, Thomas Schatzl wrote:
>> Hi Erik,
>>
>> On Thu, 2017-06-08 at 17:04 +0200, Erik Österlund wrote:
>>> Hi,
>>>
>>> There is an experimental JVM flag called ClearFPUAtPark that is used
>>> only by SPARC. It is turned off by default and is marked as Unsafe
>>> and
>>> Unstable.
>>> The idea is to tell the Solaris kernel not to save floating point
>>> registers when context switching.
>>> I propose to remove it as it is an unstable option. It relies on an
>>> implicit unstable OS contract with the kernel that may or may not be
>>> honored.
>>>
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8181785
>>>
>>> Webrev: http://cr.openjdk.java.net/~eosterlund/8181785/webrev.00/
>>>
>>> Testing: JPRT
>>>
>>> Will need a sponsor.
>>
>>    looks good apart from copyright dates.
>>
>> As even experimental VM options are part of the public VM interface, I
>> think you need to do a CSR request.
>>
>> Further I think we can't just remove these options but need to use the
>> usual option deprecation/removal process.
>
> Hi, here the runtime process:
> http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2015-June/015277.html 
>
>
>     release 1: Deprecate & Handle - warn and keep supporting
>     release 2: Deprecate & Obsolete - warn and do nothing
>     release 3: Dead - unrecognized
>
> But in this case I suggest going for 2 directly and let CSR guys 
> object if so..
>
> /Robbin
>
>>
>> Thanks,
>>    Thomas
>>