Building OpenJDK (including the "portable" RPMs on RISC-V (P550)
================================================================

25Apr2025

Summary
-------

There are two parts to building OpenJDK: we first need to build a
"openjdk-portable" set of RPMs, and then use that to bootstrap the main
OpenJDK.  

(See the official README here:
https://gitlab.com/redhat/centos-stream/rpms/java-21-openjdk/-/blob/c10s/README.md)

First build the "openjdk-portable"
----------------------------------

- I used FVF's patch from their "portable-centos-9-risc64" branch to build
  the "portable" OpenJDK RPMs.  That's my branch with their patch:

    https://gitlab.com/kchamart/centos_rpms_java-21-openjdk/-/commit/e30d42bf26455
    (Allow generating 'openjdk-portable' RPMs)

- I also had to s/%patch/%%patch/ in the spec files.

- Generate the SRPM (note, this is *intentional* that we're using `c9s`
  here to generate the "portable" SRPM):

   $ centpkg --release c9s srpm
   ...

- Run a `mock` build:

   $ mock -r /etc/mock/centos-stream-10-riscv64.cfg \
     ./java-21-openjdk-portable-21.0.6.0.7-1.rv64.el9.src.rpm

    (Time to build on P550: 4h9min)

- That's it!  Save these generated "portable" RPMs, as it'll be used as
  "input" for the next step.

Building the main 'java-openjdk'
--------------------------------

- Switch to my "main" OpenJDK 'dist-git', with this patch:

    https://gitlab.com/kchamart/centos_rpms_java-21-openjdk/-/commit/3c971675d9470ae43df2
    (Enable riscv64 arch)

  A crucial bit of change in there is this macro;

    %global portablerelease 1.rv64

  It is matching the "portable" RPM versions we've built above.  This is
  necessary for the build to succeed.

- Create an SRPM:

    $ centpkg --release c10s srpm
    Wrote: /home/kashyapc/src/centos-stream/dist-git/java-21-openjdk/java-21-openjdk-21.0.6.0.7-3.rv.0.el10.src.rpm

- Start a clean `chroot` and installed the "portable" RPMs:

    $ mock -r /etc/mock/centos-stream-10-riscv64.cfg --init

    $ mock -r /etc/mock/centos-stream-10-riscv64.cfg --install \
       java-21-openjdk-portable-unstripped-21.0.6.0.7-1.rv64.el10.riscv64.rpm
       java-21-openjdk-portable-docs-21.0.6.0.7-1.rv64.el10.riscv64.rpm \
       java-21-openjdk-portable-misc-21.0.6.0.7-1.rv64.el10.riscv64.rpm \
       java-21-openjdk-portable-static-libs-21.0.6.0.7-1.rv64.el10.riscv64.rpm \
       java-21-openjdk-portable-21.0.6.0.7-1.rv64.el10.riscv64.rpm \
       java-21-openjdk-portable-devel-21.0.6.0.7-1.rv64.el10.riscv64.rpm

- Generate the 'java-21-openjdk' SRPM for CS10:

    $ centpkg --release c10s srpm 
    ...
    Wrote: /home/kashyapc/src/centos-stream/dist-git/java-21-openjdk/java-21-openjdk-21.0.6.0.7-3.rv.0.el10.src.rpm

- Trigger a mock build to produce 'java-21-openjdk' RPMs for
  CS10 (*without* cleaning the 'chroot' so that the earlier installed
  "portable" RPMs remain intact): 

    $ time mock -r /etc/mock/centos-stream-10-riscv64.cfg \
      --no-clean \
      --rebuild ./java-21-openjdk-21.0.6.0.7-3.rv.0.el10.src.rpm

    (Time to build on P550: 17m54s)

That's it!