[RFC] Proposal to backport JEP 386 (Alpine Linux Port) to 11u

[Thomas Stüfe]

Hi Alexei,

I think this makes sense and is probably less risky than backporting JEP
388 and JEP 391. Thanks for doing the work, this looks well prepared for
review already.

I have some questions, which had not been immediately clear from the mail.
I may be just slow.

- Did you have to make 11u specific changes to the individual backports? If
yes, what and why?
- are there changes to the glibc variant in 11u, and if yes, why? In other
words, will anything change for the existing platforms? Because
theoretically, nothing should, right? I see the change to isnan, is that
motivated to just applying the upstream patch without change, or was there
a deeper reason?

Thank you!

Thomas


On Thu, Feb 17, 2022 at 3:12 PM Aleksei Voitylov <
aleksei.voitylov at bell-sw.com> wrote:

> Hi,
>
> Following recent backports of JEP 388 (Windows/AArch64 Port) and JEP 391
> (macOS/AArch64 Port), I’d like to propose a backport of JEP 386 (Alpine
> Linux Port) [1] to OpenJDK 11u. Support for this port was baked in the
> Portola project and integrated into OpenJDK 16.
>
> Motivation for 11u backport: the importance of this platform is
> explained by wide adoption of Alpine Linux in container environments
> [2]. Several OpenJDK vendors (Liberica, Corretto, Zulu) include patches
> that enable Alpine/MUSL for 11u and 8u for quite some time, without any
> issues. Others (MS) have recently added it. In our case the user demand
> for Alpine/musl support for both 11u and 8u was at least as strong as
> Mac/AArch64 and Windows/AArch64, I’d also like to hear if other OpenJDK
> vendors share our view of the importance of this platform in 11u.
>
> The set of JBS issues required to be backported for Alpine/MUSL support
> in 11u is:
>
> JDK-8217340 Compilation failed: tools/launcher/Test7029048.java
> -    Test-only fix
> JDK-8247592 refactor test/jdk/tools/launcher/Test7029048.java
> -    Test-only fix
> JDK-8245938 Remove unused print_stack(void) method from XToolkit.c
> -    Code fix, removal of dead code, applies cleanly
> JDK-8252248 __SIGRTMAX is not declared in musl libc
> -    Code fix
> JDK-8252250 isnanf is obsolete
> -    Code fix, substitutes isnanf with isnan which was proven to be ok
> at least since GLIBC 2.8/GCC 4.6 on Linux and any reasonable LLVM
> version – see the discussion in JDK-8178689 for further details.
> JDK-8247589 Implementation of Alpine Linux/x64 Port
> -    The actual build and code changes that tidy up code for MUSL
> JDK-8247591 Document Alpine Linux build steps in OpenJDK build guide
> -    Docs only fix
>
> All patches combined: +480 lines, -146 lines.
> All source code changes: +133 lines, -43 lines.
>
> For risk assessment and preliminary examination of the 11u maintainers,
> the full patchset can be observed in [3], separate 11u backports can be
> found in [4]. I plan to submit the actual PRs for individual backports
> one by one unless I hear reasonable concerns from 11u maintainers on the
> proposed changes.
>
> The patchset passes full JCK+jtreg set without any regressions to other
> platforms (Windows, Linux, Mac, Solaris), including non-Intel where
> applicable. During integration of JEP 386 SAP kindly verified that these
> changes do not break AIX/XLC.
>
> On the maintenance side, BellSoft will be happy to support this platform
> in 11u. But I’ll equally happily share the burden with other OpenJDK
> vendors that currently support Alpine/MUSL.
>
> Thanks,
> -Aleksei
>
> [1] https://openjdk.java.net/jeps/386
> [2] https://hub.docker.com/_/alpine
> [3]
>
> https://github.com/voitylov/jdk11u-dev/compare/d6bf0d1e7dac4f4820e5c16ca14a162717b5818d..920d286d8da398797738fbfd1eaf02e1f887e306
> [4]
> 8217340:
>
> https://github.com/voitylov/jdk11u-dev/commit/01542ba865c518c2b5d827d6c0b95488129b658a
> 8247592:
>
> https://github.com/voitylov/jdk11u-dev/commit/48a1e49807cc189cd23c569f4b28f20282010ffd
> 8245938:
>
> https://github.com/voitylov/jdk11u-dev/commit/3e41399c3471c6664302e6487d8003ecaff5e23a
> 8252248:
>
> https://github.com/voitylov/jdk11u-dev/commit/bd2a506a2f44e7e2c9a0007f256e5c2288cfbe34
> 8252250:
>
> https://github.com/voitylov/jdk11u-dev/commit/41b6b490fe60c640c90d9e594557215e669955cc
> 8247589:
>
> https://github.com/voitylov/jdk11u-dev/commit/b0562ab5e2aa23f27803832f3854f0538f51b891
> 8247591:
>
> https://github.com/voitylov/jdk11u-dev/commit/920d286d8da398797738fbfd1eaf02e1f887e306
>
>
>