# A "platform" is the GNU cpu-type/manufacturer/operating-system target machine
# specifier. E.g. sparc-sun-solaris2
+#
+# Build platform: the platform on which we are doing this build
+# Host platform: the platform on which these binaries will run
+# Target platform: the platform for which this compiler will generate code
+#
+# We don't support build & host being different, because the build
+# process creates binaries that are run during the build, and also
+# installed.
+#
+# If host & target are different, then we are building a compiler
+# which will generate intermediate .hc files to port to the target
+# architecture for bootstrapping. The libraries and stage 2 compiler
+# will be built as HC files for the target system, and likely won't
+# build on this host platform.
+#
+# Guidelines for when to use HOST vs. TARGET:
+#
+# - In the build system (Makefile, foo.mk), normally we should test
+# $(HOSTPLATFORM). There are some cases (eg. installation), where
+# we expect $(HOSTPLATFORM)==$(TARGETPLATFORM), so in those cases it
+# doesn't matter which is used.
+#
+# - In the compiler itself, we should test HOST or TARGET depending
+# on whether the conditional relates to the code being generated, or
+# the platform on which the compiler is running. For stage 2,
+# HOSTPLATFORM should be reset to be TARGETPLATFORM (we currently
+# don't do this, but we should).
+#
+# - In the RTS and library code, we should be testing TARGET only.
+#
+# NOTE: cross-compiling is not well supported by the build system.
+# You have to do a lot of work by hand to cross compile: see the
+# section on "Porting GHC" in the Building Guide.
HOSTPLATFORM = @HostPlatform@
TARGETPLATFORM = @TargetPlatform@
-BUILDPLATFORM = @HostPlatform@
+BUILDPLATFORM = @BuildPlatform@
# Hack alert:
-# in one or two places, we need to get at the OS version (major and perhaps even minor),
-# HostOS_Full is the OS name reported by AC_CANONICAL_SYSTEM.
+# in one or two places, we need to get at the OS version (major and
+# perhaps even minor), HostOS_Full is the OS name reported by
+# AC_CANONICAL_SYSTEM.
#
HostPlatform_CPP = @HostPlatform_CPP@
HostArch_CPP = @HostArch_CPP@
HostOS_Full = @HostOS_Full@
HostVendor_CPP = @HostVendor_CPP@
-#
-# ToDo: check if these can be purged now. -- sof
-#
+TargetPlatform_CPP = @TargetPlatform_CPP@
+TargetArch_CPP = @TargetArch_CPP@
+TargetOS_CPP = @TargetOS_CPP@
+TargetVendor_CPP = @TargetVendor_CPP@
+
+BuildPlatform_CPP = @BuildPlatform_CPP@
+BuildArch_CPP = @BuildArch_CPP@
+BuildOS_CPP = @BuildOS_CPP@
+BuildVendor_CPP = @BuildVendor_CPP@
-@HostPlatform_CPP@_HOST = 1
-@HostPlatform_CPP@_TARGET = 1
-@HostPlatform_CPP@_BUILD = 1
+@HostPlatform_CPP@_HOST = 1
+@TargetPlatform_CPP@_TARGET = 1
+@BuildPlatform_CPP@_BUILD = 1
-@HostArch_CPP@_HOST_ARCH = 1
-@HostArch_CPP@_TARGET_ARCH = 1
-@HostArch_CPP@_BUILD_ARCH = 1
+@HostArch_CPP@_HOST_ARCH = 1
+@TargetArch_CPP@_TARGET_ARCH = 1
+@BuildArch_CPP@_BUILD_ARCH = 1
-@HostOS_CPP@_HOST_OS = 1
-@HostOS_CPP@_TARGET_OS = 1
-@HostOS_CPP@_BUILD_OS = 1
+@HostOS_CPP@_HOST_OS = 1
+@TargetOS_CPP@_TARGET_OS = 1
+@BuildOS_CPP@_BUILD_OS = 1
-@HostVendor_CPP@_HOST_VENDOR = 1
-@HostVendor_CPP@_TARGET_VENDOR = 1
-@HostVendor_CPP@_BUILD_VENDOR = 1
+@HostVendor_CPP@_HOST_VENDOR = 1
+@TargetVendor_CPP@_TARGET_VENDOR = 1
+@BuildVendor_CPP@_BUILD_VENDOR = 1
# Leading underscores on symbol names in object files
# Valid options: YES/NO