HotSpot just got Hotter - IcedTea6 support for latest HotSpot

[Mark Wielaard]

On Tue, 2008-12-02 at 09:37 +0000, Gary Benson wrote:
> Mark Wielaard wrote:
> > I think that supporting more than 2, lets call them "stable" and
> > "latest", might be a bit ambitious.  We risk having to try to keep
> > up with all the different versions and duplicating all our patches
> > against more and more versions.
> 
> I'd extend this and say can we not just support one?  When Andrew said
> he was doing this last Thursday, my original thought was "great, we
> can get rid of all this two-versions-of-HotSpot stuff", so the thought
> of not only retaining it but possibly adding more is... unpleasant.
> 
> My biggest issue was that, when there were problems with patches where
> there were two versions of something -- usually because of a new
> OpenJDK build -- people would often just fix one version and leave the
> other.  So I'd wake up in the morning and suddenly my stuff wouldn't
> build and I'd spend all day making a fix that turned out to have
> already been applied in the "other" HotSpot.  This is why I developed
> Shark out of the main tree fwiw.  It was easier for me to deal with a
> huge dislocation every month or so -- when I was ready for it -- rather
> than potentially every day.

Yeah. So it might be good to better write down the requirements and
reasons to make hotspot upgrading easier:

- The current hotspot on openjdk6 is just too old, we keep adding more
and more backported patches for crasher bugs that we know are fixed in
later versions or build fixes for newer/older toolchains on gnu/linux
distros (we are carrying about 25 such patches now, excluding the sparc,
zero and shark work).
- The build setup of hotspot in openjdk6 is different from the main
hotspot repo (make versus build). This is causing a lot of the pain of
maintaining the zero/non-zero (7b24/6b13) divergences. Andrew tries to
make this work a bit easier with his HOTSPOT_MAKE_DIR addition. But
ideally we would only support hotspots with the newer build dir setup.
- We want an easy mechanism for trying out newer hotspots so you can
easily build a newer version and let people try out performance
improvements or new features/flags (but on top of the stable 6 core
build). I really like this part of Andrew's patch, which lets you select
either a hg revision/version number or a prepackaged hotspot src zip.
- We want to support the linux/sparc bits (the various
icedtea-sparc-*.patches). Some of this is actually already in newer
hotspots.
- We want to support zero/shark. Ideally without having to have separate
sets of ZERO_PATCHES and NON_ZERO_PATCHES (all our NON_ZERO_PATCHES are
actually rebases of ZERO_PATCHES to older hotspot versions). This
requires a hotspot that includes at a minimum the C++ interpreter.

What is the best way to combine all these properties and keep our
maintance level as low as possible. Which hotspot version(s) to support
by default that make it easy to provide support for all of the above
requirements. Did I forget anything?

Cheers,

Mark