On Sun, 28 Feb 2021 14:08:37 GMT, Andrew Haley <a...@openjdk.org> wrote:
>> Before this fix, the alignment is defaulting to that of the build host. We >> would like to provide a way to produce a JDK distribution, with a pre >> generated CDS archive, where the alignment has the highest known value of >> any target host for maximum compatibility. The currently known such values >> are 64K for Linux and 16K for Mac. If we aren't going to allow the user >> (builder of OpenJDK) the free choice of any alignment anyway, would it make >> sense to limit the choice between something more abstract like "host" and >> "compatible" instead of listing explicit numbers? >> >> Regardless of how the option is constructed, it will need some explanation >> in doc/building.md. >> >> Finally there is the question of if "host" or "compatible" should be the >> default. I see good arguments for both sides, as long as there is an option >> to switch between the too that isn't too cryptic to understand. > >> Before this fix, the alignment is defaulting to that of the build host. We >> would like to provide a way to produce a JDK distribution, with a pre >> generated CDS archive, where the alignment has the highest known value of >> any target host for maximum compatibility. The currently known such values >> are 64K for Linux and 16K for Mac. If we aren't going to allow the user >> (builder of OpenJDK) the free choice of any alignment anyway, would it make >> sense to limit the choice between something more abstract like "host" and >> "compatible" instead of listing explicit numbers? > > That's problematic because it assumes we know all of the possible > alignments. At the present time we think that 64 is the largest we'll ever > encounter, but IMO that isn't a great way to think about things. It would be > very nice indeed if we didn't have to edit OpenJDK for the next page size. I > guess 4k, 16k, and 64k are all we'll ever see, but I wouldn't bet the farm on > it. > >> Finally there is the question of if "host" or "compatible" should be the >> default. I see good arguments for both sides, as long as there is an option >> to switch between the too that isn't too cryptic to understand. > > I would have thought that "host" made the most sense, but I don't really mind. > _Mailing list message from [Andrew Haley](mailto:a...@redhat.com) on > [hotspot-runtime-dev](mailto:hotspot-runtime-...@openjdk.java.net):_ > > Hmm. I'm not convinced by making the numeric argument here a free field. > I'd allow precisely two options, "4k" and "64k", and if any crazy person > needs to add "1M" in the future, let them do so. I now realize this was wrong, because at least 16k exists as well. ------------- PR: https://git.openjdk.java.net/jdk/pull/2651
