configs: disable emulators that require it if libfdt is not found

Since boards can express their dependency on libfdt and
system/device_tree.c, only leave TARGET_NEED_FDT if the target has a
hard dependency.

Those emulators will be skipped if libfdt is disabled, or if it
is "auto" and not found and --disable-download is passed; unless
the target is mentioned explicitly in --target-list, in which case
the build will fail.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

.gitlab-ci.d/buildtest.yml

@@ -648,8 +648,8 @@ build-tci:
     - make check-tcg
 
 # Check our reduced build configurations
-# requires libfdt: aarch64, arm, i386, loongarch64, microblaze, microblazeel,
-#   mips64el, or1k, ppc, ppc64, riscv32, riscv64, rx, x86_64
+# requires libfdt: aarch64, arm, loongarch64, microblaze, microblazeel,
+#   or1k, ppc64, riscv32, riscv64, rx
 # fails qtest without boards: i386, x86_64
 build-without-defaults:
   extends: .native_build_job_template
@@ -665,8 +665,8 @@ build-without-defaults:
       --disable-qom-cast-debug
       --disable-strip
     TARGETS: alpha-softmmu avr-softmmu cris-softmmu hppa-softmmu m68k-softmmu
-      mips-softmmu mips64-softmmu mipsel-softmmu
-      s390x-softmmu sh4-softmmu sh4eb-softmmu sparc-softmmu
+      mips-softmmu mips64-softmmu mipsel-softmmu mips64el-softmmu
+      ppc-softmmu s390x-softmmu sh4-softmmu sh4eb-softmmu sparc-softmmu
       sparc64-softmmu tricore-softmmu xtensa-softmmu xtensaeb-softmmu
       hexagon-linux-user i386-linux-user s390x-linux-user
     MAKE_CHECK_ARGS: check

configs/targets/aarch64-softmmu.mak

@@ -3,4 +3,5 @@ TARGET_BASE_ARCH=arm
 TARGET_SUPPORTS_MTTCG=y
 TARGET_KVM_HAVE_GUEST_DEBUG=y
 TARGET_XML_FILES= gdb-xml/aarch64-core.xml gdb-xml/aarch64-fpu.xml gdb-xml/arm-core.xml gdb-xml/arm-vfp.xml gdb-xml/arm-vfp3.xml gdb-xml/arm-vfp-sysregs.xml gdb-xml/arm-neon.xml gdb-xml/arm-m-profile.xml gdb-xml/arm-m-profile-mve.xml gdb-xml/aarch64-pauth.xml
+# needed by boot.c
 TARGET_NEED_FDT=y

configs/targets/arm-softmmu.mak

@@ -1,4 +1,5 @@
 TARGET_ARCH=arm
 TARGET_SUPPORTS_MTTCG=y
 TARGET_XML_FILES= gdb-xml/arm-core.xml gdb-xml/arm-vfp.xml gdb-xml/arm-vfp3.xml gdb-xml/arm-vfp-sysregs.xml gdb-xml/arm-neon.xml gdb-xml/arm-m-profile.xml gdb-xml/arm-m-profile-mve.xml
+# needed by boot.c
 TARGET_NEED_FDT=y

configs/targets/i386-softmmu.mak

@@ -1,5 +1,4 @@
 TARGET_ARCH=i386
 TARGET_SUPPORTS_MTTCG=y
-TARGET_NEED_FDT=y
 TARGET_KVM_HAVE_GUEST_DEBUG=y
 TARGET_XML_FILES= gdb-xml/i386-32bit.xml

configs/targets/loongarch64-softmmu.mak

@@ -2,4 +2,5 @@ TARGET_ARCH=loongarch64
 TARGET_BASE_ARCH=loongarch
 TARGET_SUPPORTS_MTTCG=y
 TARGET_XML_FILES= gdb-xml/loongarch-base32.xml gdb-xml/loongarch-base64.xml gdb-xml/loongarch-fpu.xml
+# all boards require libfdt
 TARGET_NEED_FDT=y

configs/targets/microblaze-softmmu.mak

@@ -1,5 +1,6 @@
 TARGET_ARCH=microblaze
 TARGET_BIG_ENDIAN=y
 TARGET_SUPPORTS_MTTCG=y
+# needed by boot.c
 TARGET_NEED_FDT=y
 TARGET_XML_FILES=gdb-xml/microblaze-core.xml gdb-xml/microblaze-stack-protect.xml

configs/targets/microblazeel-softmmu.mak

@@ -1,4 +1,5 @@
 TARGET_ARCH=microblaze
 TARGET_SUPPORTS_MTTCG=y
+# needed by boot.c
 TARGET_NEED_FDT=y
 TARGET_XML_FILES=gdb-xml/microblaze-core.xml gdb-xml/microblaze-stack-protect.xml

configs/targets/mips64el-softmmu.mak

@@ -1,3 +1,2 @@
 TARGET_ARCH=mips64
 TARGET_BASE_ARCH=mips
-TARGET_NEED_FDT=y

configs/targets/or1k-softmmu.mak

@@ -1,4 +1,5 @@
 TARGET_ARCH=openrisc
 TARGET_SUPPORTS_MTTCG=y
 TARGET_BIG_ENDIAN=y
+# needed by boot.c and all boards
 TARGET_NEED_FDT=y

configs/targets/ppc-softmmu.mak

@@ -2,4 +2,3 @@ TARGET_ARCH=ppc
 TARGET_BIG_ENDIAN=y
 TARGET_KVM_HAVE_GUEST_DEBUG=y
 TARGET_XML_FILES= gdb-xml/power-core.xml gdb-xml/power-fpu.xml gdb-xml/power-altivec.xml gdb-xml/power-spe.xml
-TARGET_NEED_FDT=y

configs/targets/ppc64-softmmu.mak

@@ -4,4 +4,5 @@ TARGET_BIG_ENDIAN=y
 TARGET_SUPPORTS_MTTCG=y
 TARGET_KVM_HAVE_GUEST_DEBUG=y
 TARGET_XML_FILES= gdb-xml/power64-core.xml gdb-xml/power-fpu.xml gdb-xml/power-altivec.xml gdb-xml/power-spe.xml gdb-xml/power-vsx.xml
+# all boards require libfdt
 TARGET_NEED_FDT=y

configs/targets/riscv32-softmmu.mak

@@ -2,4 +2,5 @@ TARGET_ARCH=riscv32
 TARGET_BASE_ARCH=riscv
 TARGET_SUPPORTS_MTTCG=y
 TARGET_XML_FILES= gdb-xml/riscv-32bit-cpu.xml gdb-xml/riscv-32bit-fpu.xml gdb-xml/riscv-64bit-fpu.xml gdb-xml/riscv-32bit-virtual.xml
+# needed by boot.c
 TARGET_NEED_FDT=y

configs/targets/riscv64-softmmu.mak

@@ -2,4 +2,5 @@ TARGET_ARCH=riscv64
 TARGET_BASE_ARCH=riscv
 TARGET_SUPPORTS_MTTCG=y
 TARGET_XML_FILES= gdb-xml/riscv-64bit-cpu.xml gdb-xml/riscv-32bit-fpu.xml gdb-xml/riscv-64bit-fpu.xml gdb-xml/riscv-64bit-virtual.xml
+# needed by boot.c
 TARGET_NEED_FDT=y

configs/targets/rx-softmmu.mak

@@ -1,3 +1,4 @@
 TARGET_ARCH=rx
 TARGET_XML_FILES= gdb-xml/rx-core.xml
+# all boards require libfdt
 TARGET_NEED_FDT=y

configs/targets/x86_64-softmmu.mak

@@ -1,6 +1,5 @@
 TARGET_ARCH=x86_64
 TARGET_BASE_ARCH=i386
 TARGET_SUPPORTS_MTTCG=y
-TARGET_NEED_FDT=y
 TARGET_KVM_HAVE_GUEST_DEBUG=y
 TARGET_XML_FILES= gdb-xml/i386-64bit.xml

meson.build

@@ -3058,7 +3058,11 @@ foreach target : target_dirs
   config_target += { 'TARGET_' + config_target['TARGET_ARCH'].to_upper(): 'y' }
 
   if 'TARGET_NEED_FDT' in config_target and not fdt.found()
-    fdt_required += target
+    if default_targets
+      warning('Disabling ' + target + ' due to missing libfdt')
+    else
+      fdt_required += target
+    endif
     continue
   endif