tcg/plugins: enable by default for most TCG builds

Aside from a minor bloat to file size the ability to have TCG plugins
has no real impact on performance unless a plugin is actively loaded.
Even then the libempty.so plugin shows only a minor degradation in
performance caused by the extra book keeping the TCG has to do to keep
track of instructions. As it's a useful feature lets just enable it by
default and reduce our testing matrix a little.

We need to move our linker testing earlier so we can be sure we can
enable the loader module required. As we have ruled out static &
plugins in an earlier patch we can also reduce the indent a little.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210709143005.1554-33-alex.bennee@linaro.org>

.gitlab-ci.d/buildtest.yml

@@ -354,29 +354,6 @@ build-some-softmmu:
     TARGETS: xtensa-softmmu arm-softmmu aarch64-softmmu alpha-softmmu
     MAKE_CHECK_ARGS: check-tcg
 
-# Run check-tcg against linux-user (with plugins)
-# we skip sparc64-linux-user until it has been fixed somewhat
-# we skip cris-linux-user as it doesn't use the common run loop
-build-user-plugins:
-  extends: .native_build_job_template
-  needs:
-    job: amd64-debian-user-cross-container
-  variables:
-    IMAGE: debian-all-test-cross
-    CONFIGURE_ARGS: --disable-tools --disable-system --enable-plugins --enable-debug-tcg --target-list-exclude=sparc64-linux-user,cris-linux-user
-    MAKE_CHECK_ARGS: check-tcg
-  timeout: 1h 30m
-
-build-some-softmmu-plugins:
-  extends: .native_build_job_template
-  needs:
-    job: amd64-debian-user-cross-container
-  variables:
-    IMAGE: debian-all-test-cross
-    CONFIGURE_ARGS: --disable-tools --disable-user --enable-plugins --enable-debug-tcg
-    TARGETS: xtensa-softmmu arm-softmmu aarch64-softmmu alpha-softmmu
-    MAKE_CHECK_ARGS: check-tcg
-
 clang-system:
   extends: .native_build_job_template
   needs:

configure

@@ -429,7 +429,7 @@ libxml2="auto"
 debug_mutex="no"
 libpmem="auto"
 default_devices="true"
-plugins="no"
+plugins="$default_feature"
 fuzzing="no"
 rng_none="no"
 secret_keyring="$default_feature"
@@ -2209,6 +2209,8 @@ if test "$static" = "yes" ; then
   fi
   if test "$plugins" = "yes"; then
     error_exit "static and plugins are mutually incompatible"
+  else
+    plugins="no"
   fi
 fi
 
@@ -3102,6 +3104,69 @@ for drv in $audio_drv_list; do
     esac
 done
 
+##########################################
+# plugin linker support probe
+
+if test "$plugins" != "no"; then
+
+    #########################################
+    # See if --dynamic-list is supported by the linker
+
+    ld_dynamic_list="no"
+    cat > $TMPTXT <<EOF
+{
+  foo;
+};
+EOF
+
+        cat > $TMPC <<EOF
+#include <stdio.h>
+void foo(void);
+
+void foo(void)
+{
+  printf("foo\n");
+}
+
+int main(void)
+{
+  foo();
+  return 0;
+}
+EOF
+
+    if compile_prog "" "-Wl,--dynamic-list=$TMPTXT" ; then
+        ld_dynamic_list="yes"
+    fi
+
+    #########################################
+    # See if -exported_symbols_list is supported by the linker
+
+    ld_exported_symbols_list="no"
+    cat > $TMPTXT <<EOF
+  _foo
+EOF
+
+    if compile_prog "" "-Wl,-exported_symbols_list,$TMPTXT" ; then
+        ld_exported_symbols_list="yes"
+    fi
+
+    if test "$ld_dynamic_list" = "no" &&
+       test "$ld_exported_symbols_list" = "no" ; then
+        if test "$plugins" = "yes"; then
+            error_exit \
+                "Plugin support requires dynamic linking and specifying a set of symbols " \
+                "that are exported to plugins. Unfortunately your linker doesn't " \
+                "support the flag (--dynamic-list or -exported_symbols_list) used " \
+                "for this purpose."
+        else
+            plugins="no"
+        fi
+    else
+        plugins="yes"
+    fi
+fi
+
 ##########################################
 # glib support probe
 
@@ -3110,7 +3175,7 @@ glib_modules=gthread-2.0
 if test "$modules" = yes; then
     glib_modules="$glib_modules gmodule-export-2.0"
 fi
-if test "$plugins" = yes; then
+if test "$plugins" = "yes"; then
     glib_modules="$glib_modules gmodule-2.0"
 fi
 
@@ -3935,61 +4000,6 @@ if compile_prog "" "" ; then
   atomic64=yes
 fi
 
-#########################################
-# See if --dynamic-list is supported by the linker
-ld_dynamic_list="no"
-if test "$static" = "no" ; then
-    cat > $TMPTXT <<EOF
-{
-  foo;
-};
-EOF
-
-    cat > $TMPC <<EOF
-#include <stdio.h>
-void foo(void);
-
-void foo(void)
-{
-  printf("foo\n");
-}
-
-int main(void)
-{
-  foo();
-  return 0;
-}
-EOF
-
-    if compile_prog "" "-Wl,--dynamic-list=$TMPTXT" ; then
-        ld_dynamic_list="yes"
-    fi
-fi
-
-#########################################
-# See if -exported_symbols_list is supported by the linker
-
-ld_exported_symbols_list="no"
-if test "$static" = "no" ; then
-    cat > $TMPTXT <<EOF
-  _foo
-EOF
-
-    if compile_prog "" "-Wl,-exported_symbols_list,$TMPTXT" ; then
-        ld_exported_symbols_list="yes"
-    fi
-fi
-
-if  test "$plugins" = "yes" &&
-    test "$ld_dynamic_list" = "no" &&
-    test "$ld_exported_symbols_list" = "no" ; then
-  error_exit \
-      "Plugin support requires dynamic linking and specifying a set of symbols " \
-      "that are exported to plugins. Unfortunately your linker doesn't " \
-      "support the flag (--dynamic-list or -exported_symbols_list) used " \
-      "for this purpose."
-fi
-
 ########################################
 # check if getauxval is available.
 

docs/devel/tcg-plugins.rst

@@ -71,7 +71,8 @@ API
 Usage
 =====
 
-The QEMU binary needs to be compiled for plugin support::
+Any QEMU binary with TCG support has plugins enabled by default.
+Earlier releases needed to be explicitly enabled with::
 
   configure --enable-plugins