document cross-compiling of xtc68

README.md

@@ -89,6 +89,10 @@ sudo ./sdk-install.sh
 
 Note `sudo` is required for a non-root user to install to `/usr/local`.
 
+### Cross compiling
+
+The `cross/mkcross.sh` script supports cross-compilation hosted on Linux for MacOS and Windows (as well as generating the Linux archive). Note that the MacOS recipe has a dependency on a local path for the MacOS cross-compiler).
+
 ## Integration with native make (i.e. GNU Make)
 
 * The installation provides `ql.mk`, which it will copy to `$PREFIX/share/qdos/etc/ql.mk`

cross/mkcross.sh

@@ -3,6 +3,9 @@
 PLAT=${1:-win:mac}
 BASE=${2:-/tmp/xtc68}
 
+# There are only used for building, the prefix is not embedded in release build
+# binaries i.e. when `-Drelbuild=true` is provided to the meson setup stage.
+
 WINPFX=$BASE/windows/xtc68
 MACPFX=$BASE/macos/xtc68
 LINPFX=$BASE/linux/xtc68
@@ -30,6 +33,7 @@ mkarchive() {
 }
 
 if [[ "$PLAT" =~  "lin" ]] ; then
+  # oldest libc on site, in order to maximise cross-distro compatibility
   echo -e "\a\n*** Do the Linux release builds on Debian Stable ***\n"
   rm -rf build-linux $BASE/linux
   meson build-linux --prefix=$LINPFX --strip -Drelbuild=true