RFR: JDK-8201483 Make it possible to disable JVM features

Magnus Ihse Bursie magnus.ihse.bursie at oracle.com
Thu Apr 12 13:38:40 UTC 2018


On 2018-04-12 14:11, Thomas Stüfe wrote:
> Hi Magnus,
>
> this is nice. I would like a clearer naming though, that single dash
> is easily overlooked. How about --without-jvm-features instead?

This is not possible. --without-X is internally replaced by autoconf to 
"--with-X=no". "--without-X=foo" is a syntax error (or more, technically 
correct, an attempt to run "--with-X=foo=no").

I could of course do something like "--with-disabled-jvm-features=foo" 
instead, but I do not think that is much better. A quick internal poll 
(with Erik and some guys working on the upcoming individual GC 
selection, which prompted this fix) gave the current solution as a clear 
favorite.

A compromise is to keep the currently suggested functionality, and 
*also* add a "--with-disabled-jvm-features=foo", which I would then 
treat as  "--with-jvm-features=-foo". Is that something you'd like to 
request?

/Magnus

>
> ..Thomas
>
> On Thu, Apr 12, 2018 at 1:39 PM, Magnus Ihse Bursie
> <magnus.ihse.bursie at oracle.com> wrote:
>> It is currently easy to add new JVM features to the JVM build, but it is not
>> possible to remove features.
>>
>> With this change, features can be both added or removed from the default
>> set. They are added using --with-jvm-features=f1,f2 and removed using
>> --with-jvm-features=-f1,-f2. The syntax can be combined, so
>> --with-jvm-features=dtrace,-nmt will enable dtrace but disable native memory
>> tracking.
>>
>> I also included some additional code cleanup and fixes, such as printing the
>> JVM feature set at the summary.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8201483
>> WebRev:
>> http://cr.openjdk.java.net/~ihse/JDK-8201483-disable-JVM-features/webrev.01
>>



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