[Bug 1885827] Re: building plugin failed on Windows with mingw

[Emilio G. Cota]

You should then find out why libqemu_plugin.dll.a is not working. It is
possible though that your linked is calling the import library something
else, for instance adding a .dll extension to it.

You will have to run a few tests with your linker (I'd just use the
examples from the stackoverflow links I posted above) to see the name of
the import library that gets created. My assumption is that some library
gets created, otherwise the linked should give you an error and AFAICT
it does not.

Once you find what the import library us, you should be in good shape to
adapt the above for QEMU. Let us know how it goes!

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https://bugs.launchpad.net/bugs/1885827

Title:
  building plugin failed on Windows with mingw

Status in QEMU:
  New

Bug description:
  I want to build QEMU 4.2.0's plugin module on Windows 7/10 with Mingw, but 
the building process faild.
   
  The step I follow is listed below:
  1. create "dsp_build" diretory under source file folder

  2.  change directory to dsp_build , and run ../configure 
--target-list=dsp-softmmu --cross-prefix=x86_64-w64-mingw32- --enable-gtk 
--enable-sdl --enable-debug --enable-plugins
  3. build qemu project
  4. switch dir to /dsp_build, make -C tests/plugin, yeilds error: 
     CC      bb.o
   D:/emu_devl/qemu_src/qemu-sr-dsp-a/qemu_tidsp_c3x/tests/plugin/bb.c:17:24: 
error: variable 'qemu_plugin_version' definition is marked dllimport
     17 | QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
        |                        ^~~~~~~~~~~~~~~~~~~
   D:/emu_devl/qemu_src/qemu-sr-dsp-a/qemu_tidsp_c3x/tests/plugin/bb.c:17:24: 
warning: 'qemu_plugin_version' redeclared without dllimport attribute: previous 
dllimport ignored [-Wattributes]
   D:/emu_devl/qemu_src/qemu-sr-dsp-a/qemu_tidsp_c3x/tests/plugin/bb.c: In 
function 'vcpu_tb_exec':
   D:/emu_devl/qemu_src/qemu-sr-dsp-a/qemu_tidsp_c3x/tests/plugin/bb.c:33:29: 
warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
     33 |     unsigned long n_insns = (unsigned long)udata;
        |                             ^
   D:/emu_devl/qemu_src/qemu-sr-dsp-a/qemu_tidsp_c3x/tests/plugin/bb.c: In 
function 'vcpu_tb_trans':
   D:/emu_devl/qemu_src/qemu-sr-dsp-a/qemu_tidsp_c3x/tests/plugin/bb.c:51:46: 
warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
     51 |                                              (void *)n_insns);

  5.  Then , I modified the QEMU_flags and the compilation command
  arguments($(CC) ..) in  the  makefile :

                  BUILD_DIR := $(CURDIR)/../..

                include $(BUILD_DIR)/config-host.mak
                include $(SRC_PATH)/rules.mak

                  $(call set-vpath, $(SRC_PATH)/tests/plugin)

                NAMES :=
                NAMES += bb
                NAMES += empty
                NAMES += insn
                NAMES += mem
                NAMES += hotblocks
                NAMES += howvec
                NAMES += hotpages

                  SONAMES := $(addsuffix .so,$(addprefix lib,$(NAMES)))

                QEMU_CFLAGS += -fPIC    -DBUILDING_DLL                  #added  
-DBUILDING_DLL
                QEMU_CFLAGS += -I$(SRC_PATH)/include/qemu

                  all: $(SONAMES)

                lib%.so: %.o
                        $(CC) -fPIC -shared -o $@ $^ $(LDLIBS) -L 
/c/msys64/mingw64/lib/ -lglib-2.0
                        # original cmd: $(CC) -shared -Wl,-soname,$@ -o $@ $^ 
$(LDLIBS)

                clean:
                        rm -f *.o *.so *.d
                        rm -Rf .libs

                  .PHONY: all clean

  6.  Executing make yeilds:

  make: enter   
“/d/emu_devl/qemu_src/qemu-sr-dsp-a/qemu_tidsp_c3x/build_dsp/tests/plugin”
    CC      bb.o
  x86_64-w64-mingw32-gcc -fPIC -shared -o libbb.so bb.o  -L 
/c/msys64/mingw64/lib/ -lglib-2.0
  
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.1.0/../../../../x86_64-w64-mingw32/bin/ld.exe:
 bb.o: in function `plugin_exit':
  D:/emu_devl/qemu_src/qemu-sr-dsp-a/qemu_tidsp_c3x/tests/plugin/bb.c:28: 
undefined reference to `qemu_plugin_outs'
  
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.1.0/../../../../x86_64-w64-mingw32/bin/ld.exe:
 D:/emu_devl/qemu_src/qemu-sr-dsp-a/qemu_tidsp_c3x/tests/plugin/bb.c:29: 
undefined reference to `__stack_chk_fail'
  
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.1.0/../../../../x86_64-w64-mingw32/bin/ld.exe:
 bb.o: in function `vcpu_tb_trans':
  D:/emu_devl/qemu_src/qemu-sr-dsp-a/qemu_tidsp_c3x/tests/plugin/bb.c:41: 
undefined reference to `qemu_plugin_tb_n_insns'
  
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.1.0/../../../../x86_64-w64-mingw32/bin/ld.exe:
 D:/emu_devl/qemu_src/qemu-sr-dsp-a/qemu_tidsp_c3x/tests/plugin/bb.c:44: 
undefined reference to `qemu_plugin_register_vcpu_tb_exec_inline'
  
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.1.0/../../../../x86_64-w64-mingw32/bin/ld.exe:
 D:/emu_devl/qemu_src/qemu-sr-dsp-a/qemu_tidsp_c3x/tests/plugin/bb.c:46: 
undefined reference to `qemu_plugin_register_vcpu_tb_exec_inline'
  
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.1.0/../../../../x86_64-w64-mingw32/bin/ld.exe:
 D:/emu_devl/qemu_src/qemu-sr-dsp-a/qemu_tidsp_c3x/tests/plugin/bb.c:49: 
undefined reference to `qemu_plugin_register_vcpu_tb_exec_cb'
  
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.1.0/../../../../x86_64-w64-mingw32/bin/ld.exe:
 bb.o: in function `qemu_plugin_install':
  D:/emu_devl/qemu_src/qemu-sr-dsp-a/qemu_tidsp_c3x/tests/plugin/bb.c:63: 
undefined reference to `qemu_plugin_register_vcpu_tb_trans_cb'
  
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.1.0/../../../../x86_64-w64-mingw32/bin/ld.exe:
 D:/emu_devl/qemu_src/qemu-sr-dsp-a/qemu_tidsp_c3x/tests/plugin/bb.c:64: 
undefined reference to `qemu_plugin_register_atexit_cb'
  
C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/10.1.0/../../../../x86_64-w64-mingw32/bin/ld.exe:
 bb.o:bb.c:(.rdata$.refptr.__stack_chk_guard[.refptr.__stack_chk_guard]+0x0): 
undefined reference to `__stack_chk_guard'
  collect2.exe: error: ld returned 1 exit status

     It looks like linking problem(fail to link functions defined in api.c, 
core.c...), but I have no idea what goes wrong. If I mannualy add api.o, core.o 
in the compilation command, still get error like undefined reference to 
'__stack_chk_guard'. 
     My collegue can build 4.2.0  plugins on Ubuntu Linux without any problem.

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