On Mon, 31 Mar 2025 13:16:34 GMT, Erik Joelsson <er...@openjdk.org> wrote:
> > Wait a minute. I re-read the discussion a bit more carefully, and let my > > brain re-process what I said above... > > Is the goal here to document how you properly do cross-compilation for > > windows/aarch64 on windows/x64? If so, I think this is a correct solution, > > but the documentation should be more clear that this applies for > > cross-compiling to windows/aarch64 from x64 on cygwin. > > If the problem is that native builds on windows/aarch64 does not work, then > > it is a different issue that needs to be fixed. > > The problem applies to both native and cross compilation, though cross > compilation is no different than other platforms. The reason native > compilation doesn't work on Cygwin is that there is no aarch64 distro of > Cygwin, so even a native windows aarch64 build will use an x64 version of > Cygwin running in emulated mode (I don't know the name on Windows, but pretty > much the same as rosetta on mac). This trips up configure into thinking we > are running on a native windows x64 machine, and it's the reason why telling > configure that the **build** platform is `aarch64-pc-cygwin` helps. Caveat, > this is all based on what I've heard, I've never had access to a > windows-aarch64 machine. > > I completely agree that fixing this detection issue is better than > documenting, but I also think that documenting how to perform a native build > is better than how to perform a cross build on a native machine. Cross > compiling works, but adds increased complexity and build time unnecessarily > in this case. Upon closer inspection, the --build option results in a native build (per the build system) but the ARM64 C++ compiler binary (cl.exe) is actually an x64 binary, so the compiler is running in emulated mode despite the build system thinking that a native build is happening. I'm investigating this in https://bugs.openjdk.org/browse/JDK-8353066 I propose changing the scope of this PR to documenting cross compilation for windows/aarch64 on windows/x64 and fixing the native build in https://bugs.openjdk.org/browse/JDK-8353066 ------------- PR Comment: https://git.openjdk.org/jdk/pull/24267#issuecomment-2766469401
