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

Thu Feb 24 13:15:24 UTC 2022

Hi Alexei,

On Thu, Feb 24, 2022 at 1:56 PM Aleksei Voitylov <
aleksei.voitylov at bell-sw.com> wrote:

> Hi Thomas,
>
> see inline:
> On 23/02/2022 21:18, Thomas Stüfe wrote:
>
> 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?
>
> Speaking of product code changes, all changes that had to be done for 11u
> are cosmetic, it's mostly lines layout that had to be taken care of.
> 8252248 is slightly different because of Solaris support in 11u, but these
> changes are under #ifdefs in libnio/ch/NativeThread.c.
>
> - 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?
>
> Yes, there are changes to glibc variant in 11u which are limited to 100
> lines of code. Most of the work done for Alpine Linux support was actually
> cleanup to linux code. My take with the 11u backport is to keep it simple
> and in line with what was contributed to 16 to simplify maintenance. Let me
> break down the changes en large so you can also do the risk assessment
>
> - 8245938 removes dead code (also dead in 11u)
> - 8252248 glibc-private  __SIGRTMAX is replaced with public standard
> SIGRTMAX
> - 8252250 isnan change analysis can be found in
> https://bugs.openjdk.java.net/browse/JDK-8178689 comments
> - 8247589 First, this change uses libnuma2 if available with fallback to
> libnuma if libnuma2 is not found. Second, mmap and mprotect are called at
> VM initialization to enable JDK to work on systems with PaX grsecurity. No
> new API is used in terms of libc/glibc compatibility level. Both changes
> are not specific to Alpine (aside from the fact that Alpine enables it by
> default).
>

Seems all reasonable. Thanks for breaking it down for me.

I agree that keeping the code aligned with mainline is worth these minor
behavioral changes.

Thanks, Thomas

> Thanks,
>
> -Aleksei
>
>
> 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
>>
>>
>>