[RFC PATCH 11/12] configure: enable cross-compilation of optionrom

[Paolo Bonzini <pbonzini@redhat.com>]

While container-based cross compilers are not supported, this already makes
it possible to build x86 optionroms on any machine that has an installation
of GCC and binutils for 32- or 64-bit x86.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 configure                  | 29 +++++++++++++++++++++--------
 pc-bios/optionrom/Makefile |  4 +---
 2 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/configure b/configure
index 07ee586ef5..6b8e2e2fdb 100755
--- a/configure
+++ b/configure
@@ -2100,6 +2100,13 @@ probe_target_compiler() {
   fi
 }
 
+probe_target_compilers() {
+  for i; do
+    probe_target_compiler $i
+    test -n "$target_cc" && return 0
+  done
+}
+
 write_target_makefile() {
   if test -n "$target_cc"; then
     echo "CC=$target_cc"
@@ -2210,6 +2217,9 @@ fi
 
 QEMU_GA_MSI_MINGW_BIN_PATH="$($pkg_config --variable=prefix glib-2.0)/bin"
 
+#######################################
+# cross-compiled firmware targets
+
 # Set up build tree symlinks that point back into the source tree
 # (these can be both files and directories).
 # Caution: avoid adding files or directories here using wildcards. This
@@ -2236,19 +2246,27 @@ done
 
 # Mac OS X ships with a broken assembler
 roms=
-if { test "$cpu" = "i386" || test "$cpu" = "x86_64"; } && \
+probe_target_compilers i386 x86_64
+if test -n "$target_cc" &&
         test "$targetos" != "darwin" && test "$targetos" != "sunos" && \
         test "$targetos" != "haiku" && test "$softmmu" = yes ; then
     # Different host OS linkers have different ideas about the name of the ELF
     # emulation. Linux and OpenBSD/amd64 use 'elf_i386'; FreeBSD uses the _fbsd
     # variant; OpenBSD/i386 uses the _obsd variant; and Windows uses i386pe.
     for emu in elf_i386 elf_i386_fbsd elf_i386_obsd i386pe; do
-        if "$ld" -verbose 2>&1 | grep -q "^[[:space:]]*$emu[[:space:]]*$"; then
+        if "$target_ld" -verbose 2>&1 | grep -q "^[[:space:]]*$emu[[:space:]]*$"; then
             ld_i386_emulation="$emu"
-            roms="optionrom"
             break
         fi
     done
+    if test -n "$ld_i386_emulation"; then
+        roms="optionrom"
+        config_mak=pc-bios/optionrom/config.mak
+        echo "# Automatically generated by configure - do not modify" > $config_mak
+        echo "TOPSRC_DIR=$source_path" >> $config_mak
+        echo "LD_I386_EMULATION=$ld_i386_emulation" >> $config_mak
+        write_target_makefile >> $config_mak
+    fi
 fi
 
 # Only build s390-ccw bios the compiler has -march=z900 or -march=z10 (which is
@@ -2403,7 +2421,6 @@ echo "GLIB_CFLAGS=$glib_cflags" >> $config_host_mak
 echo "GLIB_LIBS=$glib_libs" >> $config_host_mak
 echo "GLIB_VERSION=$(pkg-config --modversion glib-2.0)" >> $config_host_mak
 echo "QEMU_LDFLAGS=$QEMU_LDFLAGS" >> $config_host_mak
-echo "LD_I386_EMULATION=$ld_i386_emulation" >> $config_host_mak
 echo "STRIP=$strip" >> $config_host_mak
 echo "EXESUF=$EXESUF" >> $config_host_mak
 
@@ -2593,10 +2610,6 @@ for target in $target_list; do
 done
 echo "TCG_TESTS_TARGETS=$tcg_tests_targets" >> $makefile)
 
-config_mak=pc-bios/optionrom/config.mak
-echo "# Automatically generated by configure - do not modify" > $config_mak
-echo "TOPSRC_DIR=$source_path" >> $config_mak
-
 if test "$skip_meson" = no; then
   cross="config-meson.cross.new"
   meson_quote() {
diff --git a/pc-bios/optionrom/Makefile b/pc-bios/optionrom/Makefile
index 2494ad9c25..6696ce010a 100644
--- a/pc-bios/optionrom/Makefile
+++ b/pc-bios/optionrom/Makefile
@@ -6,7 +6,6 @@ all: multiboot.bin multiboot_dma.bin linuxboot.bin linuxboot_dma.bin kvmvapic.bi
 # Dummy command so that make thinks it has done something
 	@true
 
-include ../../config-host.mak
 CFLAGS = -O2 -g
 
 quiet-command = $(if $(V),$1,$(if $(2),@printf "  %-7s %s\n" $2 $3 && $1, @$1))
@@ -44,13 +43,12 @@ Wa = -Wa,
 override ASFLAGS += -32
 override CFLAGS += $(call cc-option, $(Wa)-32)
 
-LD_I386_EMULATION ?= elf_i386
 override LDFLAGS = -m $(LD_I386_EMULATION) -T $(SRC_DIR)/flat.lds
 
 pvh.img: pvh.o pvh_main.o
 
 %.o: %.S
-	$(call quiet-command,$(CPP) $(CPPFLAGS) -c -o - $< | $(AS) $(ASFLAGS) -o $@,"AS","$@")
+	$(call quiet-command,$(CC) -E $(CPPFLAGS) -c -o - $< | $(AS) $(ASFLAGS) -o $@,"AS","$@")
 
 %.o: %.c
 	$(call quiet-command,$(CC) $(CPPFLAGS) $(CFLAGS) -c $< -o $@,"CC","$@")
-- 
2.35.1