Re: [Qemu-devel] Bugs when cross-compiling qemu for Windows with mingw 8.1, executable doesn't run

[Ben Pye]

I'm also seeing this behaviour using the MSYS2 packaged mingw64 compiler, GCC 
8.2. I have managed to cross compile QEMU successfully under Fedora 28 however 
and the resulting binary works. Certainly seems like a tool chain issue, 
unfortunately MSYS2 doesn't package any older versions of GCC.

Ben.

On 18 August 2018 21:51:35 BST, Howard Spoelstra <address@hidden> wrote:
>On Sat, Aug 18, 2018 at 9:09 PM, Stefan Weil <address@hidden> wrote:
>> Am 17.08.2018 um 09:32 schrieb David Hildenbrand:
>>> On 18.07.2018 08:33, Howard Spoelstra wrote:
>>>> Hi all,
>>>>
>>>> I have two issues when cross compiling current master for Windows
>with
>>>> mingw 8.1. Host is Fedora29. See further below for gcc and mingw
>>>> versions.
>>>>
>>>> Reproduce with:
>>>> ./configure --cross-prefix=x86_64-w64-mingw32-
>>>> --target-list="ppc-softmmu" --enable-gtk --with-gtkabi=3.0
>>>> --enable-sdl --with-sdlabi=2.0
>>>>
>>>> Issue 1: Two bugs show up during compilation related to strncpy.
>>>> Replacing the offenders with memcpy seems to fix this.
>>>>
>>>> First time:
>>>> block/sheepdog.c: In function 'find_vdi_name':
>>>> block/sheepdog.c:1239:5: error: 'strncpy' specified bound 256
>equals
>>>> destination size [-Werror=stringop-truncation]
>>>>      strncpy(buf + SD_MAX_VDI_LEN, tag, SD_MAX_VDI_TAG_LEN);
>>>>      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>>
>>>> Second time:
>>>> migration/global_state.c: In function 'global_state_store_running':
>>>> migration/global_state.c:45:5: error: 'strncpy' specified bound 100
>>>> equals destination size [-Werror=stringop-truncation]
>>>>      strncpy((char *)global_state.runstate,
>>>>      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>>             state, sizeof(global_state.runstate));
>>>>             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>>
>>>
>>> These two reports should be independent of general functionality
>>> (sheepdog, migration). So what you see is most likely unrelated to
>this.
>>>
>>>> Issue 2: once strncpy has been replaced with memcpy in these two
>>>> instances, I can successfully compile, but the executable doesn't
>run
>>>> in Windows.
>>>> I tried to debug, and this is what gdb told me:
>>>>
>>>> (gdb) run
>>>> Starting program: c:\qemu-fedora29beta\qemu-system-ppc-debug.exe -L
>>>> c:\qemu-fedora29beta\pc-bios -boot c -m 256 -M "mac99,via=pmu"
>>>> -prom-env "boot-args=-v" -prom-env "auto-boot?=true" -prom-env
>>>> "vga-ndrv?=true" -hda c:\Mac-disks\9.2.qcow2 -netdev
>>>> "user,id=network01" -device "sungem,netdev=network01" -sdl -d int
>>>> [New Thread 948.0x6d8]
>>>> [New Thread 948.0x2778]
>>>> [New Thread 948.0x286c]
>>>> [New Thread 948.0x3d0]
>>>>
>>>> Program received signal SIGSEGV, Segmentation fault.
>>>> getpagesize () at util/oslib-win32.c:535
>>>> 535     util/oslib-win32.c: No such file or directory.
>>>
>>> This warning is just from GDB, not able to locate you sources I
>guess.
>>>
>>>> (gdb) bt full
>>>> #0  getpagesize () at util/oslib-win32.c:535
>>>
>>> Wonder why we should get a SEGFAULT in that simple function. As
>>> discussed offline, the functionality in general seems to work (if
>this
>>> function is compiled and run independently in your environment).
>>>
>>> But maybe this backtrace is just misleading.
>>>
>>>>         system_info = {{dwOemId = 56491488, {wProcessorArchitecture
>=
>>>> 64992, wReserved = 861}}, dwPageSize = 0,
>>>>           lpMinimumApplicationAddress = 0x99cca4
>>>> <register_module_init+60>, lpMaximumApplicationAddress = 0x3,
>>>>           dwActiveProcessorMask = 11102192, dwNumberOfProcessors =
>>>> 56584576, dwProcessorType = 0,
>>>>           dwAllocationGranularity = 200, wProcessorLevel = 0,
>>>> wProcessorRevision = 0}
>>>
>>> dwPageSize = 0, I assume this is some random data on the stack and
>>> GetSystemInfo never got executed. I wonder where this segfault comes
>from.
>>>
>>>> #1  0x00000000009b7fcd in init_real_host_page_size () at
>util/pagesize.c:16
>>>> No locals.
>>>> #2  0x00000000009bc5f2 in __do_global_ctors ()
>>>> No symbol table info available.
>>>> #3  0x00000000004013ca in __tmainCRTStartup () at
>../crt/crtexe.c:324
>>>>         lock_free = <optimized out>
>>>>         fiberid = <optimized out>
>>>>         nested = <optimized out>
>>>>         lpszCommandLine = <optimized out>
>>>>         StartupInfo = {cb = 104, lpReserved = 0x3778e00 "",
>lpDesktop
>>>> = 0x377f440 "Winsta0\\Default",
>>>>           lpTitle = 0x3786280
>>>> "c:\\qemu-fedora29beta\\qemu-system-ppc-debug.exe", dwX = 0, dwY =
>0,
>>>> dwXSize = 0,
>>>>           dwYSize = 0, dwXCountChars = 0, dwYCountChars = 0,
>>>> dwFillAttribute = 0, dwFlags = 0, wShowWindow = 0,
>>>>           cbReserved2 = 0, lpReserved2 = 0x0, hStdInput =
>>>> 0xffffffffffffffff, hStdOutput = 0xffffffffffffffff,
>>>>           hStdError = 0xffffffffffffffff}
>>>>         inDoubleQuote = <optimized out>
>>>> #4  0x00000000004014fb in WinMainCRTStartup () at
>../crt/crtexe.c:184
>>>>         ret = 255
>>>> (gdb)
>>>>
>>>>
>>>> Gcc and mingw versions used:
>>>>
>>>> address@hidden qemu-master]$ gcc -v
>>>> Using built-in specs.
>>>> COLLECT_GCC=gcc
>>>>
>COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/8/lto-wrapper
>>>> OFFLOAD_TARGET_NAMES=nvptx-none
>>>> OFFLOAD_TARGET_DEFAULT=1
>>>> Target: x86_64-redhat-linux
>>>> Configured with: ../configure --enable-bootstrap
>>>> --enable-languages=c,c++,fortran,objc,obj-c++,ada,go,lto
>--prefix=/usr
>>>> --mandir=/usr/share/man --infodir=/usr/share/info
>>>> --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared
>>>> --enable-threads=posix --enable-checking=release --enable-multilib
>>>> --with-system-zlib --enable-__cxa_atexit
>>>> --disable-libunwind-exceptions --enable-gnu-unique-object
>>>> --enable-linker-build-id --with-gcc-major-version-only
>>>> --with-linker-hash-style=gnu --enable-plugin
>--enable-initfini-array
>>>> --with-isl --enable-libmpx --enable-offload-targets=nvptx-none
>>>> --without-cuda-driver --enable-gnu-indirect-function --enable-cet
>>>> --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
>>>> Thread model: posix
>>>> gcc version 8.1.1 20180626 (Red Hat 8.1.1-4) (GCC)
>>>>
>>>> address@hidden qemu-master]$ x86_64-w64-mingw32-gcc -v
>>>> Using built-in specs.
>>>> COLLECT_GCC=x86_64-w64-mingw32-gcc
>>>>
>COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-w64-mingw32/8.1.0/lto-wrapper
>>>> Target: x86_64-w64-mingw32
>>>> Configured with: ../configure --prefix=/usr --bindir=/usr/bin
>>>> --includedir=/usr/include --mandir=/usr/share/man
>>>> --infodir=/usr/share/info --datadir=/usr/share
>>>> --build=x86_64-redhat-linux-gnu --host=x86_64-redhat-linux-gnu
>>>> --with-gnu-as --with-gnu-ld --verbose --without-newlib
>>>> --disable-multilib --disable-plugin --with-system-zlib
>--disable-nls
>>>> --without-included-gettext --disable-win32-registry
>>>> --enable-languages=c,c++,objc,obj-c++,fortran
>>>> --with-bugurl=http://bugzilla.redhat.com/bugzilla --with-cloog
>>>> --enable-threads=posix --enable-libgomp --target=x86_64-w64-mingw32
>>>> --with-sysroot=/usr/x86_64-w64-mingw32/sys-root
>>>>
>--with-gxx-include-dir=/usr/x86_64-w64-mingw32/sys-root/mingw/include/c++
>>>> Thread model: posix
>>>> gcc version 8.1.0 20180502 (Fedora MinGW 8.1.0-1.fc29) (GCC)
>>>>
>>>> Thanks for looking into this,
>>>>
>>>> Best,
>>>> Howard
>>>>
>>>
>>> No being a win32/mingw expert, Stefan any idea?
>>
>>
>> I'd try a debug build (configure [...] --enable-debug).
>>
>> My installers (https://qemu.weilnetz.de/w64/) were built with
>> x86_64-w64-mingw32-gcc (GCC) 6.3.0 20170516 (from Debian Stretch).
>> Howard, perhaps you can try whether they show the same runtime
>SIGSEGV.
>> When I run your command line with a dummy disk image, OpenBIOS boots
>fine.
>>
>> Kind regards,
>> Stefan
>
>The error I reported already came from a debug build.
>Other builds with less recent mingw (7.3 in Fedora 28) do not SIGSEGV,
>neither do Stefan's.
>I can confirm the strncpy warnings are gone using Philippe's patches.
>
>Best,
>Howard