Hermetic Java and static link

[Johan Vos]

Hi Jiangli,

Thanks for sharing this info. I am wondering if you somehow create a symbol
map that is used at link time? We use the same static compilation concept
in openjdk/mobile, but simply linking `-ljava -lnio -lnet` etc will not
include the native functions (e.g. Java_java_lang_reflect_Array_get) that
are part of e.g. libjava.a etc, because they are not referenced.
This can be solved by telling the linker to use force_load (linux) but
preferably, we don't want to load symbols that are not used in the final
image. There used to be a function in the OpenJDK build process that
creates a map with relevant symbols per static library, but I'm not sure it
is still used?

- Johan

On Wed, Oct 15, 2025 at 2:21 AM Jiangli Zhou <jianglizhou at google.com> wrote:

> CC'ing leyden-dev at openjdk.org
>
> Hi Ioi,
>
> For the current state of  JDK static linking support, the
> https://github.com/openjdk/leyden/tree/hermetic-java-runtime is about
> the same as the JDK mainline. Most of the JDK libraries and libjvm are
> statically linked with the launcher. Please see additional comments
> below.
>
> On Tue, Oct 14, 2025 at 10:04 AM <ioi.lam at oracle.com> wrote:
> >
> > Hi Jiangli,
> >
> > I tried building with
> > https://github.com/openjdk/leyden/tree/hermetic-java-runtime to see if I
> > can get a completely statically linked JVM, but the JVM is still
> > dynamically linked to a few shared libraries.
>
> Could you please elaborate on the specific libraries that you are
> looking into static linking as well? Such as libm, libasound, X11, ,
> etc? What are the specific benefits for statically linking with those?
>
> Do you have some context or details on what you are looking for?
>
> >
> > Is it possible to do a static link (with "gcc-static ...")?
>
> If I understand the question correctly, -static-libgcc is the default
> when building JDK on Linux. See
>
> https://github.com/openjdk/jdk/blob/3d95c83b14cf9a6f683776053e57c07b1847cc17/make/autoconf/lib-std.m4#L50
> .
> It's the case with linking the libjvm.so as well. E.g.:
>
>   g++ ... -static-libgcc -shared ... -Wl,-soname=libjvm.so -o
> support/modules_libs/java.base/server/libjvm.so ... -lm -ldl -lpthread
> -lrt -static-libstdc++
>
>
> Thanks,
> Jiangli
>
> >
> > Thanks
> >
> > - Ioi
> >
> > $ bash configure
> > $ cd build/linux-x64
> > $ make static-jdk-bundles
> > $ ls -l build/linux-x64/images/static-jdk/bin/java
> > -rwxr-xr-x. 1 opc opc 34915696 Oct 14 08:55
> > build/linux-x64/images/static-jdk/bin/java
> > $ ldd images/static-jdk/bin/java
> >      linux-vdso.so.1 (0x000075aad82ca000)
> >      libX11.so.6 => /lib/x86_64-linux-gnu/libX11.so.6
> (0x000075aad64c3000)
> >      libXext.so.6 => /lib/x86_64-linux-gnu/libXext.so.6
> (0x000075aad829e000)
> >      libXi.so.6 => /lib/x86_64-linux-gnu/libXi.so.6 (0x000075aad828b000)
> >      libXrender.so.1 => /lib/x86_64-linux-gnu/libXrender.so.1
> > (0x000075aad827f000)
> >      libXtst.so.6 => /lib/x86_64-linux-gnu/libXtst.so.6
> (0x000075aad8277000)
> >      libasound.so.2 => /lib/x86_64-linux-gnu/libasound.so.2
> > (0x000075aad63b9000)
> >      libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x000075aad8270000)
> >      libfreetype.so.6 => /lib/x86_64-linux-gnu/libfreetype.so.6
> > (0x000075aad62ed000)
> >      libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0
> > (0x000075aad826b000)
> >      librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x000075aad8266000)
> >      libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x000075aad824a000)
> >      libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x000075aad6204000)
> >      libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x000075aad5e00000)
> >      /lib64/ld-linux-x86-64.so.2 (0x000075aad82cc000)
> >      libxcb.so.1 => /lib/x86_64-linux-gnu/libxcb.so.1
> (0x000075aad61db000)
> >      libbz2.so.1.0 => /lib/x86_64-linux-gnu/libbz2.so.1.0
> > (0x000075aad8234000)
> >      libpng16.so.16 => /lib/x86_64-linux-gnu/libpng16.so.16
> > (0x000075aad61a3000)
> >      libbrotlidec.so.1 => /lib/x86_64-linux-gnu/libbrotlidec.so.1
> > (0x000075aad6195000)
> >      libXau.so.6 => /lib/x86_64-linux-gnu/libXau.so.6
> (0x000075aad822c000)
> >      libXdmcp.so.6 => /lib/x86_64-linux-gnu/libXdmcp.so.6
> > (0x000075aad618d000)
> >      libbrotlicommon.so.1 => /lib/x86_64-linux-gnu/libbrotlicommon.so.1
> > (0x000075aad616a000)
> >      libbsd.so.0 => /lib/x86_64-linux-gnu/libbsd.so.0
> (0x000075aad6154000)
> >      libmd.so.0 => /lib/x86_64-linux-gnu/libmd.so.0 (0x000075aad6145000)
> >
>
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