Re: [PATCH v1 10/13] tests/plugins: add -Wno-unknown-warning-option to handle -Wpsabi

["Alex Bennée" <alex.bennee@linaro.org>]

Thomas Huth <thuth@redhat.com> writes:

> On 13/07/2020 18.39, Alex Bennée wrote:
>> 
>> Richard Henderson <richard.henderson@linaro.org> writes:
>> 
>>> On 7/9/20 7:13 AM, Alex Bennée wrote:
>>>> Not all compilers support the -Wpsabi (clang-9 in my case).
>>>>
>>>> Fixes: bac8d222a
>>>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>>>> ---
>>>>  tests/plugin/Makefile | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/tests/plugin/Makefile b/tests/plugin/Makefile
>>>> index 0cb8e35ae407..dcfbd99b15b8 100644
>>>> --- a/tests/plugin/Makefile
>>>> +++ b/tests/plugin/Makefile
>>>> @@ -18,7 +18,7 @@ NAMES += hwprofile
>>>>  
>>>>  SONAMES := $(addsuffix .so,$(addprefix lib,$(NAMES)))
>>>>  
>>>> -QEMU_CFLAGS += -fPIC -Wpsabi
>>>> +QEMU_CFLAGS += -fPIC -Wno-unknown-warning-option -Wpsabi
>>>
>>> Surely -Wno-unknown-warning-option is in the same boat?  E.g. I don't see any
>>> version of gcc that supports it.
>> 
>> GCC doesn't seem to complain about it though.
>
> Both, GCC and Clang do not complain about unknown -Wno-somthing options
> as long as there are no other warnings. They only complain for options
> that do not have a "no-" after the "-W".

I've done a little minor surgery on the Makefile to both limit the
pollution of the plugin build from QEMU flags and to only enable the
check if we detect the compiler supports it:

--8<---------------cut here---------------start------------->8---
tests/plugins: don't unconditionally add -Wpsabi

Not all compilers support the -Wpsabi (clang-9 in my case). To handle
this gracefully we pare back the shared build machinery so the
Makefile is relatively "standalone". We still take advantage of
config-host.mak as configure has done a bunch of probing for us but
that is it.

Fixes: bac8d222a
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

---
v2
  - separate from main build system and check probe

2 files changed, 21 insertions(+), 4 deletions(-)
configure             |  3 +++
tests/plugin/Makefile | 22 ++++++++++++++++++----

modified   configure
@@ -7115,6 +7115,9 @@ echo "GIT_UPDATE=$git_update" >> $config_host_mak
 
 echo "ARCH=$ARCH" >> $config_host_mak
 
+echo "GLIB_CFLAGS=$glib_cflags" >> $config_host_mak
+echo "GLIB_LDFLAGS=$glib_ldflags" >> $config_host_mak
+
 if test "$default_devices" = "yes" ; then
   echo "CONFIG_MINIKCONF_MODE=--defconfig" >> $config_host_mak
 else
modified   tests/plugin/Makefile
@@ -1,9 +1,16 @@
+# -*- Mode: makefile -*-
+#
+# This Makefile example is fairly independent from the main makefile
+# so users can take and adapt it for their build. We only really
+# include config-host.mak so we don't have to repeat probing for
+# cflags that the main configure has already done for us.
+#
+
 BUILD_DIR := $(CURDIR)/../..
 
 include $(BUILD_DIR)/config-host.mak
-include $(SRC_PATH)/rules.mak
 
-$(call set-vpath, $(SRC_PATH)/tests/plugin)
+VPATH += $(SRC_PATH)/tests/plugin
 
 NAMES :=
 NAMES += bb
@@ -18,11 +25,18 @@ NAMES += hwprofile
 
 SONAMES := $(addsuffix .so,$(addprefix lib,$(NAMES)))
 
-QEMU_CFLAGS += -fPIC -Wpsabi
-QEMU_CFLAGS += -I$(SRC_PATH)/include/qemu
+# The main QEMU uses Glib extensively so it's perfectly fine to use it
+# in plugins (which many example do).
+CFLAGS = $(GLIB_CFLAGS)
+CFLAGS += -fPIC
+CFLAGS += $(if $(findstring no-psabi,$(QEMU_CFLAGS)),-Wpsabi)
+CFLAGS += -I$(SRC_PATH)/include/qemu
 
 all: $(SONAMES)
 
+%.o: %.c
+	$(CC) $(CFLAGS) -c -o $@ $<
+
 lib%.so: %.o
 	$(CC) -shared -Wl,-soname,$@ -o $@ $^ $(LDLIBS)
 
--8<---------------cut here---------------end--------------->8---


-- 
Alex Bennée