RFR 8211268: Disable unsupported GCs for Zero

[Severin Gehwolf]

On Fri, 2018-09-28 at 08:48 -0700, Erik Joelsson wrote:
> Hello,
> 
> Looks ok to me.
> 
> It will look confusing on linux-x64 where it first says:
> 
> checking if zgc should be built... yes
> 
> But then quietly disables it anyway. Not a big issue and probably not 
> worth fixing given that zero on that platform is a rather rare 
> configuration (unless for testing purposes).

Hmm, wouldn't this only show up on a configure like this?

$ configure --with-jvm-features=zgc --with-jvm-variants=zero [...]

If so, who would really do this? So IMO, not worth fixing.

Thanks,
Severin

> /Erik
> 
> 
> On 2018-09-28 02:49, Aleksey Shipilev wrote:
> > RFE:
> >   https://bugs.openjdk.java.net/browse/JDK-8211268
> > 
> > Webrev:
> >    http://cr.openjdk.java.net/~shade/8211268/webrev.01/
> > 
> > Not all GCs are supported by Zero, because it requires implementing the GC barriers in C++
> > interpreter. Now that we have jvm features that can selectively disable particular GCs, we can only
> > build supported GCs. This avoids surprise build failures like these:
> >    https://bugs.openjdk.java.net/browse/JDK-8211228
> > 
> > Testing: x86_64 Zero build, running GCBasher with the rest of GCs
> > 
> > Thanks,
> > -Aleksey
> > 
> 
>