From: Marc-André Lureau <marcandre.lureau@redhat.com>

Use meson wrap fallback for libfdt. Simplify handling of
fallback/internal build and get rid of a submodule.

This drops support for ./configure --enable-fdt=git/--enable-fdt=internal:
if the system version is enough, it will use it, otherwise it can fall back
on the wrapped subproject.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 configure                     | 21 -------------
 meson.build                   | 56 +++++------------------------------
 .gitignore                    |  1 +
 .gitmodules                   |  3 --
 dtc                           |  1 -
 meson_options.txt             |  5 ++--
 scripts/meson-buildoptions.sh |  4 +--
 subprojects/dtc.wrap          |  6 ++++
 8 files changed, 18 insertions(+), 79 deletions(-)
 delete mode 160000 dtc
 create mode 100644 subprojects/dtc.wrap

diff --git a/configure b/configure
index 02b4aa4ce9..051a5cc69b 100755
--- a/configure
+++ b/configure
@@ -297,8 +297,6 @@ vfio_user_server="disabled"
 # are included in the automatically generated help message)
 
 # 1. Track which submodules are needed
-fdt="auto"
-
 # 2. Automatically enable/disable other options
 tcg="auto"
 cfi="false"
@@ -860,14 +858,6 @@ for opt do
   ;;
   --disable-cfi) cfi="false"
   ;;
-  --disable-fdt) fdt="disabled"
-  ;;
-  --enable-fdt) fdt="enabled"
-  ;;
-  --enable-fdt=git) fdt="internal"
-  ;;
-  --enable-fdt=*) fdt="$optarg"
-  ;;
   --with-coroutine=*) coroutine="$optarg"
   ;;
   --with-git=*) git="$optarg"
@@ -1546,16 +1536,6 @@ if ! compile_prog "$glib_cflags -Werror" "$glib_libs" ; then
     fi
 fi
 
-##########################################
-# fdt probe
-
-case "$fdt" in
-  auto | enabled | internal)
-    # Simpler to always update submodule, even if not needed.
-    git_submodules="${git_submodules} dtc"
-    ;;
-esac
-
 ##########################################
 # check and set a backend for coroutine
 
@@ -2597,7 +2577,6 @@ if test "$skip_meson" = no; then
 
   # QEMU options
   test "$cfi" != false && meson_option_add "-Dcfi=$cfi"
-  test "$fdt" != auto && meson_option_add "-Dfdt=$fdt"
   test -n "${LIB_FUZZING_ENGINE+xxx}" && meson_option_add "-Dfuzzing_engine=$LIB_FUZZING_ENGINE"
   test "$qemu_suffix" != qemu && meson_option_add "-Dqemu_suffix=$qemu_suffix"
   test "$smbd" != '' && meson_option_add "-Dsmbd=$smbd"
diff --git a/meson.build b/meson.build
index 77d2ae87e4..9017141d7d 100644
--- a/meson.build
+++ b/meson.build
@@ -2759,54 +2759,14 @@ endif
 
 fdt = not_found
 if have_system
-  fdt_opt = get_option('fdt')
-  if fdt_opt in ['enabled', 'auto', 'system']
-    have_internal = fs.exists(meson.current_source_dir() / 'dtc/libfdt/Makefile.libfdt')
-    fdt = cc.find_library('fdt', kwargs: static_kwargs,
-                          required: fdt_opt == 'system' or
-                                    fdt_opt == 'enabled' and not have_internal)
-    if fdt.found() and cc.links('''
-       #include <libfdt.h>
-       #include <libfdt_env.h>
-       int main(void) { fdt_find_max_phandle(NULL, NULL); return 0; }''',
-         dependencies: fdt)
-      fdt_opt = 'system'
-    elif fdt_opt == 'system'
-       error('system libfdt requested, but it is too old (1.5.1 or newer required)')
-    elif have_internal
-      fdt_opt = 'internal'
-    else
-      fdt_opt = 'disabled'
-      fdt = not_found
+    # libfdt is not always shipped with a pkgconfig file.
+    fdt = cc.find_library('fdt', kwargs: static_kwargs, required: false)
+    if not fdt.found() or not cc.has_function('fdt_find_max_phandle', dependencies: fdt)
+      fdt = dependency('fdt', kwargs: static_kwargs,
+                method: 'pkg-config', version: '>=1.5.1',
+                required: (get_option('fdt').auto() and fdt_required.length() > 0) or get_option('fdt').enabled(),
+                default_options: ['python=disabled', 'tools=false'])
     endif
-  endif
-  if fdt_opt == 'internal'
-    fdt_files = files(
-      'dtc/libfdt/fdt.c',
-      'dtc/libfdt/fdt_ro.c',
-      'dtc/libfdt/fdt_wip.c',
-      'dtc/libfdt/fdt_sw.c',
-      'dtc/libfdt/fdt_rw.c',
-      'dtc/libfdt/fdt_strerror.c',
-      'dtc/libfdt/fdt_empty_tree.c',
-      'dtc/libfdt/fdt_addresses.c',
-      'dtc/libfdt/fdt_overlay.c',
-      'dtc/libfdt/fdt_check.c',
-    )
-
-    fdt_inc = include_directories('dtc/libfdt')
-    libfdt = static_library('fdt',
-                            build_by_default: false,
-                            sources: fdt_files,
-                            include_directories: fdt_inc)
-    fdt = declare_dependency(link_with: libfdt,
-                             include_directories: fdt_inc)
-  endif
-else
-  fdt_opt = 'disabled'
-endif
-if not fdt.found() and fdt_required.length() > 0
-  error('fdt not available but required by targets ' + ', '.join(fdt_required))
 endif
 
 config_host_data.set('CONFIG_CAPSTONE', capstone.found())
@@ -3989,7 +3949,7 @@ summary_info += {'Linux io_uring support': linux_io_uring}
 summary_info += {'ATTR/XATTR support': libattr}
 summary_info += {'RDMA support':      rdma}
 summary_info += {'PVRDMA support':    have_pvrdma}
-summary_info += {'fdt support':       fdt_opt == 'disabled' ? false : fdt_opt}
+summary_info += {'fdt support':       fdt}
 summary_info += {'libcap-ng support': libcap_ng}
 summary_info += {'bpf support':       libbpf}
 summary_info += {'spice protocol support': spice_protocol}
diff --git a/.gitignore b/.gitignore
index 1ea59f4819..13662d4f24 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,4 +21,5 @@ GTAGS
 *.patch
 *.gcov
 
+/subprojects/dtc
 /subprojects/slirp
diff --git a/.gitmodules b/.gitmodules
index 6ce5bf49c5..410a00d566 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -13,9 +13,6 @@
 [submodule "roms/qemu-palcode"]
 	path = roms/qemu-palcode
 	url = https://gitlab.com/qemu-project/qemu-palcode.git
-[submodule "dtc"]
-	path = dtc
-	url = https://gitlab.com/qemu-project/dtc.git
 [submodule "roms/u-boot"]
 	path = roms/u-boot
 	url = https://gitlab.com/qemu-project/u-boot.git
diff --git a/dtc b/dtc
deleted file mode 160000
index b6910bec11..0000000000
--- a/dtc
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit b6910bec11614980a21e46fbccc35934b671bd81
diff --git a/meson_options.txt b/meson_options.txt
index fc9447d267..493100ba4c 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -279,9 +279,8 @@ option('vduse_blk_export', type: 'feature', value: 'auto',
 
 option('capstone', type: 'feature', value: 'auto',
        description: 'Whether and how to find the capstone library')
-option('fdt', type: 'combo', value: 'auto',
-       choices: ['disabled', 'enabled', 'auto', 'system', 'internal'],
-       description: 'Whether and how to find the libfdt library')
+option('fdt', type: 'feature', value: 'auto',
+       description: 'libfdt device tree library')
 
 option('selinux', type: 'feature', value: 'auto',
        description: 'SELinux support in qemu-nbd')
diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh
index 009fab1515..2a8e91a60c 100644
--- a/scripts/meson-buildoptions.sh
+++ b/scripts/meson-buildoptions.sh
@@ -24,8 +24,6 @@ meson_options_help() {
   printf "%s\n" '  --enable-debug-mutex     mutex debugging support'
   printf "%s\n" '  --enable-debug-stack-usage'
   printf "%s\n" '                           measure coroutine stack usage'
-  printf "%s\n" '  --enable-fdt[=CHOICE]    Whether and how to find the libfdt library'
-  printf "%s\n" '                           (choices: auto/disabled/enabled/internal/system)'
   printf "%s\n" '  --enable-fuzzing         build fuzzing targets'
   printf "%s\n" '  --enable-gcov            Enable coverage tracking.'
   printf "%s\n" '  --enable-gprof           QEMU profiling with gprof'
@@ -91,6 +89,7 @@ meson_options_help() {
   printf "%s\n" '  dmg             dmg image format support'
   printf "%s\n" '  docs            Documentations build support'
   printf "%s\n" '  dsound          DirectSound sound support'
+  printf "%s\n" '  fdt             libfdt device tree library'
   printf "%s\n" '  fuse            FUSE block device export'
   printf "%s\n" '  fuse-lseek      SEEK_HOLE/SEEK_DATA support for FUSE exports'
   printf "%s\n" '  gcrypt          libgcrypt cryptography support'
@@ -262,7 +261,6 @@ _meson_option_parse() {
     --disable-dsound) printf "%s" -Ddsound=disabled ;;
     --enable-fdt) printf "%s" -Dfdt=enabled ;;
     --disable-fdt) printf "%s" -Dfdt=disabled ;;
-    --enable-fdt=*) quote_sh "-Dfdt=$2" ;;
     --enable-fuse) printf "%s" -Dfuse=enabled ;;
     --disable-fuse) printf "%s" -Dfuse=disabled ;;
     --enable-fuse-lseek) printf "%s" -Dfuse_lseek=enabled ;;
diff --git a/subprojects/dtc.wrap b/subprojects/dtc.wrap
new file mode 100644
index 0000000000..da789704d0
--- /dev/null
+++ b/subprojects/dtc.wrap
@@ -0,0 +1,6 @@
+[wrap-git]
+url = https://github.com/dgibson/dtc.git
+revision = 72fc810c3025f07de718f5f32a290a6cd5d1f4ee
+
+[provide]
+fdt = libfdt_dep
-- 
2.39.2