meson: add modules infrastructure

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Makefile

@@ -266,7 +266,7 @@ slirp/all: .git-submodule-status
 		CFLAGS="$(QEMU_CFLAGS) $(CFLAGS)" LDFLAGS="$(QEMU_LDFLAGS)")
 
 $(filter %/all, $(TARGET_DIRS_RULES)): libqemuutil.a $(common-obj-y) \
-	$(qom-obj-y)
+	$(qom-obj-y) block.syms qemu.syms
 
 $(filter %/fuzz, $(TARGET_DIRS_RULES)): libqemuutil.a $(common-obj-y) \
 	$(qom-obj-y) $(crypto-user-obj-$(CONFIG_USER_ONLY))
@@ -474,14 +474,6 @@ install: all $(if $(BUILD_DOCS),install-doc) \
 ifneq ($(TOOLS),)
 	$(call install-prog,$(TOOLS),$(DESTDIR)$(bindir))
 endif
-ifneq ($(CONFIG_MODULES),)
-	$(INSTALL_DIR) "$(DESTDIR)$(qemu_moddir)"
-	for s in $(modules-m:.mo=$(DSOSUF)); do \
-		t="$(DESTDIR)$(qemu_moddir)/$$(echo $$s | tr / -)"; \
-		$(INSTALL_LIB) $$s "$$t"; \
-		test -z "$(STRIP)" || $(STRIP) "$$t"; \
-	done
-endif
 ifneq ($(HELPERS-y),)
 	$(call install-prog,$(HELPERS-y),$(DESTDIR)$(libexecdir))
 endif

Makefile.target

@@ -162,6 +162,12 @@ obj-y += qapi/
 obj-y += migration/ram.o
 LIBS := $(libs_softmmu) $(LIBS)
 
+# Temporary until emulators are linked by Meson
+LIBS := $(LIBS) @../block.syms @../qemu.syms
+ifneq ($(CONFIG_MODULES),y)
+LIBS := $(LIBS)
+endif
+
 # Hardware support
 ifeq ($(TARGET_NAME), sparc64)
 obj-y += hw/sparc64/

meson.build

@@ -10,6 +10,7 @@ sh = find_program('sh')
 cc = meson.get_compiler('c')
 config_host = keyval.load(meson.current_build_dir() / 'config-host.mak')
 config_all_disas = keyval.load(meson.current_build_dir() / 'config-all-disas.mak')
+enable_modules = 'CONFIG_MODULES' in config_host
 
 add_project_arguments(config_host['QEMU_CFLAGS'].split(),
                       native: false, language: ['c', 'objc'])
@@ -316,6 +317,7 @@ genh += hxdep
 util_ss = ss.source_set()
 stub_ss = ss.source_set()
 trace_ss = ss.source_set()
+block_ss = ss.source_set()
 common_ss = ss.source_set()
 softmmu_ss = ss.source_set()
 user_ss = ss.source_set()
@@ -323,6 +325,7 @@ bsd_user_ss = ss.source_set()
 linux_user_ss = ss.source_set()
 specific_ss = ss.source_set()
 
+modules = {}
 hw_arch = {}
 target_arch = {}
 target_softmmu_arch = {}
@@ -432,6 +435,12 @@ subdir('crypto')
 subdir('storage-daemon')
 subdir('ui')
 
+
+if enable_modules
+  libmodulecommon = static_library('module-common', files('module-common.c') + genh, pic: true, c_args: '-DBUILD_DSO')
+  modulecommon = declare_dependency(link_whole: libmodulecommon, compile_args: '-DBUILD_DSO')
+endif
+
 # Build targets from sourcesets
 
 stub_ss = stub_ss.apply(config_all, strict: false)
@@ -448,6 +457,48 @@ subdir('io')
 subdir('fsdev')
 subdir('target')
 
+block_mods = []
+softmmu_mods = []
+foreach d, list : modules
+  foreach m, module_ss : list
+    if enable_modules and targetos != 'windows'
+      module_ss = module_ss.apply(config_host, strict: false)
+      sl = static_library(d + '-' + m, [genh, module_ss.sources()],
+                          dependencies: [modulecommon, module_ss.dependencies()], pic: true)
+      if d == 'block'
+        block_mods += sl
+      else
+        softmmu_mods += sl
+      endif
+    else
+      if d == 'block'
+        block_ss.add_all(module_ss)
+      else
+        softmmu_ss.add_all(module_ss)
+      endif
+    endif
+  endforeach
+endforeach
+
+nm = find_program('nm')
+undefsym = find_program('scripts/undefsym.sh')
+block_syms = custom_target('block.syms', output: 'block.syms',
+                             input: [libqemuutil, block_mods],
+                             capture: true,
+                             command: [undefsym, nm, '@INPUT@'])
+qemu_syms = custom_target('qemu.syms', output: 'qemu.syms',
+                             input: [libqemuutil, softmmu_mods],
+                             capture: true,
+                             command: [undefsym, nm, '@INPUT@'])
+
+foreach m : block_mods + softmmu_mods
+  shared_module(m.name(),
+                name_prefix: '',
+                link_whole: m,
+                install: true,
+                install_dir: config_host['qemu_moddir'])
+endforeach
+
 common_ss.add_all(when: 'CONFIG_SOFTMMU', if_true: softmmu_ss)
 common_ss.add_all(when: 'CONFIG_USER_ONLY', if_true: user_ss)
 

rules.mak

@@ -61,17 +61,17 @@ endif
 # This is necessary because the exectuable itself may not use the function, in
 # which case the function would not be linked in. Then the DSO loading will
 # fail because of the missing symbol.
-process-archive-undefs = $(filter-out %.a %.fa %.mo,$1) \
+process-archive-undefs = $(filter-out %.a %.fa %.mo %$(DSOSUF),$1) \
                 $(addprefix $(WL_U), \
                      $(filter $(call defined-symbols,$(filter %.a %.fa, $1)), \
-                              $(call undefined-symbols,$(filter %.mo,$1)))) \
+		$(call undefined-symbols,$(filter %.mo %$(DSOSUF),$1)))) \
 		$(foreach l,$(filter %.fa,$1),$(call whole-archive,$l)) \
 		$(filter %.a,$1)
 
-extract-libs = $(strip $(foreach o,$(filter-out %.mo,$1),$($o-libs)))
+extract-libs = $(strip $(foreach o,$(filter-out %.mo %$(DSOSUF),$1),$($o-libs)))
 expand-objs = $(strip $(sort $(filter %.o,$1)) \
-                  $(foreach o,$(filter %.mo,$1),$($o-objs)) \
-                  $(filter-out %.o %.mo,$1))
+		$(foreach o,$(filter %.mo %$(DSOSUF),$1),$($o-objs)) \
+		$(filter-out %.o %.mo %$(DSOSUF),$1))
 
 %.o: %.c
 	@mkdir -p $(dir $@)

scripts/undefsym.sh

+#! /usr/bin/env bash
+
+# Before a shared module's DSO is produced, a static library is built for it
+# and passed to this script.  The script generates -Wl,-u options to force
+# the inclusion of symbol from libqemuutil.a if the shared modules need them,
+# This is necessary because the modules may use functions not needed by the
+# executable itself, which would cause the function to not be linked in.
+# Then the DSO loading would fail because of the missing symbol.
+
+if test $# -le 2; then
+  exit 0
+fi
+
+NM=$1
+staticlib=$2
+shift 2
+# Find symbols defined in static libraries and undefined in shared modules
+comm -12 \
+  <( $NM -P -g $staticlib | awk '$2!="U"{print "-Wl,-u," $1}' | sort -u) \
+  <( $NM -P -g "$@" | awk '$2=="U"{print "-Wl,-u," $1}' | sort -u)