kconfig: allow compiling out QEMU device tree code per target

Introduce a new Kconfig symbol, CONFIG_DEVICE_TREE, that specifies whether
to include the common device tree code in system/device_tree.c and to
link to libfdt.  For now, include it unconditionally if libfdt is
available.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 13 insertions, 15 deletions

diff --git a/system/device_tree-stub.c b/system/device_tree-stub.c
new file mode 100644
index 0000000..bddda6f
--- /dev/null
+++ b/system/device_tree-stub.c
@@ -0,0 +1,10 @@
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qapi/qapi-commands-machine.h"
+
+#ifdef CONFIG_FDT
+void qmp_dumpdtb(const char *filename, Error **errp)
+{
+    error_setg(errp, "This machine doesn't have a FDT");
+}
+#endif
diff --git a/system/device_tree.c b/system/device_tree.c
index eb5166c..2e38259 100644
--- a/system/device_tree.c
+++ b/system/device_tree.c
@@ -668,20 +668,6 @@ void qmp_dumpdtb(const char *filename, Error **errp)
     }
 }
 
-void hmp_dumpdtb(Monitor *mon, const QDict *qdict)
-{
-    const char *filename = qdict_get_str(qdict, "filename");
-    Error *local_err = NULL;
-
-    qmp_dumpdtb(filename, &local_err);
-
-    if (hmp_handle_error(mon, local_err)) {
-        return;
-    }
-
-    info_report("dtb dumped to %s", filename);
-}
-
 void qemu_fdt_randomize_seeds(void *fdt)
 {
     int noffset, poffset, len;
diff --git a/system/meson.build b/system/meson.build
index 25e2117..a296270 100644
--- a/system/meson.build
+++ b/system/meson.build
@@ -32,7 +32,9 @@ if have_tpm
 endif
 
 system_ss.add(when: seccomp, if_true: files('qemu-seccomp.c'))
-system_ss.add(when: fdt, if_true: files('device_tree.c'))
+system_ss.add(when: 'CONFIG_DEVICE_TREE',
+              if_true: [fdt, files('device_tree.c')],
+              if_false: files('device_tree-stub.c'))
 if host_os == 'linux'
   system_ss.add(files('async-teardown.c'))
 endif