syslinux: rewrite recipe so only target code is x86-specific

Currently the syslinux recipe set COMPATIBLE_HOST to 32/64-bit x86.
Whilst this makes sense for the target binaries as syslinux is
x86-specific, this also affects the native recipe which should be able
to be built on non-x86 build hosts (for example, arm64 build host,
qemux86 target).

syslinux itself has a somewhat fragile build system but with care it is
possible to build the installer for native/nativesdk, and the bootloader
for target.

(From OE-Core rev: 7273e131bfc7de83df9e90697e7983d54b713798)

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/syslinux/syslinux_6.04-pre2.bb

@@ -4,10 +4,7 @@ LICENSE = "GPLv2+"
 LIC_FILES_CHKSUM = "file://COPYING;md5=0636e73ff0215e8d672dc4c32c317bb3 \
                     file://README;beginline=35;endline=41;md5=558f2c71cb1fb9ba511ccd4858e48e8a"
 
-# If you really want to run syslinux, you need mtools.  We just want the
-# ldlinux.* stuff for now, so skip mtools-native
 DEPENDS = "nasm-native util-linux e2fsprogs"
-PV = "6.04-pre2"
 
 SRC_URI = "https://www.zytor.com/pub/syslinux/Testing/6.04/syslinux-${PV}.tar.xz \
            file://syslinux-remove-clean-script.patch \
@@ -27,64 +24,77 @@ SRC_URI = "https://www.zytor.com/pub/syslinux/Testing/6.04/syslinux-${PV}.tar.xz
 SRC_URI[md5sum] = "2b31c78f087f99179feb357da312d7ec"
 SRC_URI[sha256sum] = "4441a5d593f85bb6e8d578cf6653fb4ec30f9e8f4a2315a3d8f2d0a8b3fadf94"
 
+RECIPE_NO_UPDATE_REASON = "6.04-pre3 is broken"
 UPSTREAM_CHECK_URI = "https://www.zytor.com/pub/syslinux/"
 UPSTREAM_CHECK_REGEX = "syslinux-(?P<pver>.+)\.tar"
 UPSTREAM_VERSION_UNKNOWN = "1"
 
-COMPATIBLE_HOST = '(x86_64|i.86).*-(linux|freebsd.*)'
+# We can build the native parts anywhere, but the target has to be x86
+COMPATIBLE_HOST_class-target = '(x86_64|i.86).*-(linux|freebsd.*)'
+
 # Don't let the sanity checker trip on the 32 bit real mode BIOS binaries
 INSANE_SKIP_${PN}-misc = "arch"
 INSANE_SKIP_${PN}-chain = "arch"
 
+# When building the installer, CC is used to link. When building the bootloader,
+# LD is used. However, these variables assume that GCC is used and break the
+# build, so unset them.
+TARGET_LDFLAGS = ""
+SECURITY_LDFLAGS = ""
+LDFLAGS_SECTION_REMOVAL = ""
+
 EXTRA_OEMAKE = " \
 	BINDIR=${bindir} SBINDIR=${sbindir} LIBDIR=${libdir} \
 	DATADIR=${datadir} MANDIR=${mandir} INCDIR=${includedir} \
+	CC="${CC} ${CFLAGS} ${LDFLAGS}" \
+	LD="${LD} ${LDFLAGS}" \
+	OBJDUMP="${OBJDUMP}" \
+	OBJCOPY="${OBJCOPY}" \
+	AR="${AR}" \
+	STRIP="${STRIP}" \
+	NM="${NM}" \
+	RANLIB="${RANLIB}" \
 "
 
+#
+# Tasks for native/nativesdk which just build the installer.
+#
 do_configure() {
-	# drop win32 targets or build fails
-	sed -e 's,win32/\S*,,g' -i Makefile
-
-	# clean installer executables included in source tarball
-	oe_runmake clean firmware="efi32" EFIINC="${includedir}"
-	# NOTE: There is a temporary work around above to specify
-	#	the efi32 as the firmware else the pre-built bios
-	#	files get erased contrary to the doc/distib.txt
-	#	In the future this should be "bios" and not "efi32".
+	oe_runmake firmware="bios" clean
 }
 
 do_compile() {
-	# Make sure the recompile is OK.
-	# Though the ${B} should always exist, still check it before find and rm.
-	[ -d "${B}" ] && find ${B} -name '.*.d' -type f -exec rm -f {} \;
-
-	# Rebuild only the installer; keep precompiled bootloaders
-	# as per author's request (doc/distrib.txt)
-	oe_runmake CC="${CC} ${CFLAGS}" \
-                   LD="${LD}" LDFLAGS="${LDFLAGS}" \
-                   OBJDUMP="${OBJDUMP}" \
-                   OBJCOPY="${OBJCOPY}" \
-                   AR="${AR}" \
-                   STRIP="${STRIP}" \
-                   NM="${NM}" \
-                   RANLIB="${RANLIB}" \
-                   firmware="bios" installer
+	oe_runmake firmware="bios" installer
 }
 
 do_install() {
-	oe_runmake CC="${CC} ${CFLAGS}" LD="${LD}" \
-                   OBJDUMP="${OBJDUMP}" \
-                   OBJCOPY="${OBJCOPY}" \
-                   AR="${AR}" \
-                   STRIP="${STRIP}" \
-                   NM="${NM}" \
-                   RANLIB="${RANLIB}" \
-                   firmware="bios" install INSTALLROOT="${D}"
+	install -d ${D}${bindir}
+	install \
+		${B}/bios/mtools/syslinux \
+		${B}/bios/extlinux/extlinux \
+		${B}/bios/utils/isohybrid \
+		${D}${bindir}
+}
+
+#
+# Tasks for target which ship the precompiled bootloader and installer
+#
+do_configure_class-target() {
+	# No need to do anything as we're mostly shipping the precompiled binaries
+	:
+}
+
+do_compile_class-target() {
+	# No need to do anything as we're mostly shipping the precompiled binaries
+	:
+}
+
+do_install_class-target() {
+	oe_runmake firmware="bios" install INSTALLROOT="${D}"
 
 	install -d ${D}${datadir}/syslinux/
 	install -m 644 ${S}/bios/core/ldlinux.sys ${D}${datadir}/syslinux/
 	install -m 644 ${S}/bios/core/ldlinux.bss ${D}${datadir}/syslinux/
-	install -m 755 ${S}/bios/linux/syslinux-nomtools ${D}${bindir}/
 }
 
 PACKAGES += "${PN}-nomtools ${PN}-extlinux ${PN}-mbr ${PN}-chain ${PN}-pxelinux ${PN}-isolinux ${PN}-misc"