On 19/07/2024 09:08, Carlo B. via Cygwin wrote:
Hello,
GCC development branch includes experimental support Windows on ARM64
(WOA), which will be officially released next year with version 15, at
least according to latest news.
So, I compiled it and I created a number of packages for CYGWIN
including binutils, gcc, mingw runtime and several libraries, not
released yet to my repository.
Although the "aarch64-w64-mingw32" target is still experimental, I
have to say that this cross compiler worked very well, at least until
now.
Great work! We'd certainly welcome and appreciate your help getting
packages for this into our repository, also.
However, some problems appear because there are some thirdy party
tools not expecting to have mingw combined with something different
than i686 or x86_64.
For example, it is impossible to create a shared library when using
libtool, more details could be found here:
https://savannah.gnu.org/support/?111081
Huh. I guess someone should fix that, then!
I think for a start, the regex around line 5724 in libtool (near the
comment about keeping it in sync with _LT_CHECK_MAGIC_METHOD) needs
updating to match arm64 archives...
For this reason, you have to use CMake or other alternative tools
instead of autotools.
Actually, another problem can happen when creating the packages for
CYGWIN with CYGPORT utility.
For example, I tried to build a noarch package of libpng for CYGWIN,
by using the new aarch64-w64-mingw32.
I have used CMake to bypass the above trouble with libtool.
Unfortunately, the build process still fails because it didn't compile
the sources for adding the functions with NEON acceleration.
The cause of the problem is the variable CMAKE_SYSTEM_PROCESSOR that is empty.
This is not a bug of CMake, because CMAKE_SYSTEM_PROCESSOR is
typically set into CMAKE_TOOLCHAIN_FILE by the user when cross
compiling.
At the moment, I bypassed the trouble by adding
"-DCMAKE_SYSTEM_PROCESSOR=aarch64" to CYGCMAKE_ARGS into my script.
I gave a look into /usr/share/cygport/cygclass/cmake.cygclass and it
seems to me that there is nothing for setting the CPU type.
Perhaps it would be worth to add support for setting
CMAKE_SYSTEM_PROCESSOR into cmake.cygclass, by checking the content of
${CTARGET}, if it exists with a known CPU.
Interesting.
I took a look and there are several existing packages which have been
cross-built for x86 and x86_64 MinGW using cmake, so either it seems
this hasn't yet appeared as a problem for those arches and/or packages...
It's not terribly clear what the valid values are for that cmake
variable, and what it controls, but the answer [1] makes it seem like
it's not a lot:
[1]
https://stackoverflow.com/questions/70475665/what-are-the-possible-values-of-cmake-system-processor
But yeah, this seems eminently fixable in cygport, something like the
attached I think.
From 5848205bc46e3598f40d4658e7a17eccd3bedbb6 Mon Sep 17 00:00:00 2001
From: Jon Turney <jon.tur...@dronecode.org.uk>
Date: Sat, 20 Jul 2024 15:23:01 +0100
Subject: [PATCH cygport] cmake: Define CMAKE_SYSTEM_PROCESSOR when
cross-compiling
---
cygclass/cmake.cygclass | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/cygclass/cmake.cygclass b/cygclass/cmake.cygclass
index d2a7ef09..3ed4238e 100644
--- a/cygclass/cmake.cygclass
+++ b/cygclass/cmake.cygclass
@@ -82,6 +82,19 @@ __cmake_system() {
echo -n ${cmsys}
}
+__cmake_proc() {
+ local cmproc
+
+ case ${CHOST} in
+ x86_64-*) cmproc="x86_64" ;;
+ i686-*) cmproc="i686" ;;
+ aarch64-*) cmproc="aarch64" ;;
+ *) error "Host ${CHOST} is not supported by CMake" ;;
+ esac
+
+ echo -n ${cmproc}
+}
+
#****C* cmake.cygclass/cygcmake
# SYNOPSIS
# cygcmake [OPTIONS]
@@ -142,6 +155,7 @@ cygcmake() {
if cross_compiling
then
crossargs="-DCMAKE_SYSTEM_NAME=$(__cmake_system)
+ -DCMAKE_SYSTEM_PROCESSOR=$(__cmake_proc)
-D_CMAKE_TOOLCHAIN_PREFIX=${CHOST}-
-DCMAKE_FIND_ROOT_PATH=$(${CC} -print-sysroot)
-DCMAKE_FIND_ROOT_PATH_MODE_INCLUDE=ONLY
@@ -236,4 +250,4 @@ src_install() {
}
#****
-readonly -f __cmake_system cygcmake
+readonly -f __cmake_system __cmake_proc cygcmake
--
2.45.1
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