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<p>Hello,</p>
<p>Yes, the limitations in possible cross compiling scenarios is a
known issue. We have so far not had need for cross compiling
across different toolchain types or operating systems. While
cleaning this up could be a worthy goal, please also keep in mind
that big changes like this will require careful review and testing
and such resources may be limited, so such work could potentially
drag out. This isn't meant to say don't do it, I'm just trying to
set expectations.</p>
<p>/Erik</p>
<div class="moz-cite-prefix">On 12/17/25 03:44, Alexey Ivanov wrote:<br>
</div>
<blockquote type="cite" cite="mid:4a629239-c084-452a-be50-c5587342d374@oracle.com">
Hi Antoni,<br>
<br>
This discussion belongs in build-dev mailing list.<br>
<br>
-- <br>
Regards,<br>
Alexey<br>
<br>
<div class="moz-cite-prefix">On 2025-12-17 11:22, Antoni Jankowski
wrote:<br>
</div>
<blockquote type="cite" cite="mid:CAM4sPk-53EY=HqyfxVL7Z2vLjvss-2jeBROPrh=GeQfWT8zAHw@mail.gmail.com">
<div dir="ltr">
<div dir="ltr">
<div>Hi, </div>
<div><br>
</div>
<div>I've recently studied the jdk21u build system and
noticed that at its core it is not meant to handle
BUILDJDK and TARGETJDK being made for two very different
systems. </div>
<div>Many of the FLAGS are shared between the two and in
many cases that may be problematic. A good example is the
GENDEPS_FLAGS variable, which is only present in one
version, just in the <i>make/autoconf/<a href="http://spec.gmk.in" target="_blank" moz-do-not-send="true">spec.gmk.in</a></i>, meaning
that the BUILDJDK gets the same GENDEPS_FLAGS as the
TARGETJDK. Shouldn't this variable be split into
GENDEPS_FLAGS_TARGET and GENDEPS_FLAGS_BUILD to ensure a
correct generation of dependency files in all sorts of
cross-compilation scenarios?</div>
<div><br>
</div>
<div>Same story is with the variables defined in <i>make/autoconf/flags-cflags.m4,
make/autoconf/flags-ldflags.m4 and
make/autoconf/flags-other.m4, </i>like<br>
* $2CFLAGS_JDKEXE</div>
<div>* $2CXXFLAGS_JDKEXE</div>
<div>* $2CFLAGS_JDKLIB</div>
<div>as they all depend on the OPENJDK_TARGET_OS variable,
which is the same for both TARGETJDK and BUILDJDK. I
suppose the root of the problem is right there, where in <i><a href="http://build-spec.gmk.in" target="_blank" moz-do-not-send="true">build-spec.gmk.in</a></i> the
OPENJDK_TARGET_OS variable is not overwritten with the
value of OPENJDK_BUILD_OS, like it's done with other
OPENJDK_TARGET_* variables. I suppose no problems occur
when the compiler is shared between the target and the
build platforms, even less problems in case of linux or
macOS in both cases being the operating system, however in
case of the target system differing greatly from the
build, the cross-compilation is close to impossible with
the current build system.</div>
<div><br>
</div>
<div>I wonder if that is a design choice, or perhaps a
limitation that was not planned.</div>
<div>Would you be open for changes that make it a bit easier
to introduce a new platform target to <span class="gmail-il">openjdk</span>? I'd gladly post a pull
request solving the issues mentioned.</div>
<div><br>
</div>
<div>Best regards,</div>
<div>Antoni Jankowski</div>
</div>
</div>
</blockquote>
</blockquote>
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