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Re: [Qemu-devel] crashes with win2008 host

From: KONRAD Frederic
Subject: Re: [Qemu-devel] crashes with win2008 host
Date: Mon, 17 Sep 2018 09:54:15 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1

Hi Andrew,

Le 09/14/2018 à 06:54 PM, Andrew Baumann a écrit :
Thanks for digging into this Fred, and sorry -- it seems Andrey and I both 
missed that subtlety with TryAcquireSRWLockExclusive when we first made this 

On the other hand, since these OSes are a decade old (mainstream support ended; 
will drop out of extended support in just over a year from now), and you are 
the first person to report a problem in 1.5 years since the patch went in, I 
wonder if we could “fix” the problem by updating the required OS versions for 
QEMU on Windows to Windows 7 / Server 2008 R2...

Paolo, do you have any opinion? Note that backing out the patch isn’t a great 
idea either – it fixed a deadlock.

Reverting was not the idea, I was just confused by the fact that
it was theorically possible to run this QEMU under Vista and
Server 2008 and looked for a workaround.. Bumping the requirement
seems a good idea to me.



From: KONRAD Frederic <address@hidden>
Sent: Friday, September 14, 2018 4:17:36 AM
To: Andrew Baumann; Andrey Shedel
Cc: Paolo Bonzini; QEMU Developers
Subject: Re: [Qemu-devel] crashes with win2008 host

Ok finally got it,

The SRWL API seems to be available since Vista and Server 2008
except the 'TryAcquireSRWLockExclusive' function which is
available starting Seven and Server 2008 *R2*. Hence the error

So basically that means QEMU is not compatible with version older
than Seven or 2008 R2.


Le 09/14/2018 à 10:29 AM, KONRAD Frederic a écrit :

Le 09/13/2018 à 07:29 PM, Andrew Baumann a écrit :
Does this crash always happen at startup? Is it deterministic?

Hi Andrew,

Thanks for your reactivity! Yes it crashes all the time..

c0000135 is STATUS_DLL_NOT_FOUND. I suspect ntdll is trying to
demand-load another DLL to provide that API, and it is missing
or corrupt on your Windows installation

Actually that helps! Compiling in debug mode gave me this
errors.. But it wasn't the error I was chasing..

The initial error I was chasing is the following:
    gdb: unknown target exception 0xc0000139 at 0x77636698

When I execute it in graphic mode I get the following issue:

    The procedure entry point TryAcquireSRWLockExclusive could not
    be located in the dynamic link library KERNEL32.dll.

It seems that there was the same issue raised with MySQL on
Windows server 2008:

Is there anything I can do appart swaping back locally to the CS?


BTW, you’ll probably get a better stack trace from a native
debugger (windbg, etc.) in this scenario.



From: KONRAD Frederic <address@hidden>
Sent: Thursday, September 13, 2018 10:02:56 AM
To: Andrey Shedel
Cc: Andrew Baumann; Paolo Bonzini; QEMU Developers
Subject: crashes with win2008 host

Hi Andrey,

I've strange crashes since this commit: (yes its old)

commit 12f8def0e02232d7c6416ad9b66640f973c531d1
Author: Andrey Shedel <address@hidden>
Date:   Fri Mar 24 15:01:41 2017 -0700

       win32: replace custom mutex and condition variable with
              native primitives

Basically it just crashes.. (exception 0xc0000135) like this:

(gdb) run
Starting program: C:\home\konrad\temp\qemu-system-sparc --version
[New Thread 5324.0xdf8]
gdb: unknown target exception 0xc0000135 at 0x77636698
gdb: unknown target exception 0xc0000135 at 0x77636698

Program received signal ?, Unknown signal.
0x0000000077636698 in ntdll!RtlRaiseStatus ()
      from C:\Windows\system32\ntdll.dll
(gdb) bt
#0  0x0000000077636698 in ntdll!RtlRaiseStatus ()
      from C:\Windows\system32\ntdll.dll
#1  0x00000000775dcbf7 in ntdll!LdrGetProcedureAddress ()
      from C:\Windows\system32\ntdll.dll
#2  0x00000000775a536e in ntdll!LdrInitializeThunk ()
      from C:\Windows\system32\ntdll.dll
#3  0x0000000000000000 in ?? ()
Backtrace stopped: previous frame inner to this frame (corrupt

Sorry the backtrace is not really helpful..

I can reproduce the same behavior with v3.0.0.. and only with
the Windows 2008 server host..

If I partially revert the patch, eg: using CriticalSection
instead of SRWL it seems to work.. But I don't understand why
because SRWL should be supported on 2008 Server..

Here is the change I did (which is wrongly making qemu_mutex
recursive for now):

diff --git a/include/qemu/thread-win32.h
index d668d789b4..b335687604 100644
--- a/include/qemu/thread-win32.h
+++ b/include/qemu/thread-win32.h
@@ -4,7 +4,8 @@
    #include <windows.h>

    struct QemuMutex {
-    SRWLOCK lock;
+    LONG owner;
        const char *file;
        int line;
diff --git a/util/qemu-thread-win32.c b/util/qemu-thread-win32.c
index b303188a36..09ce4fd957 100644
--- a/util/qemu-thread-win32.c
+++ b/util/qemu-thread-win32.c
@@ -45,7 +45,7 @@ static void error_exit(int err, const char *msg)

    void qemu_mutex_init(QemuMutex *mutex)
-    InitializeSRWLock(&mutex->lock);
+    InitializeCriticalSection(&mutex->lock);

@@ -53,14 +53,14 @@ void qemu_mutex_destroy(QemuMutex *mutex)
        mutex->initialized = false;
-    InitializeSRWLock(&mutex->lock);
+    DeleteCriticalSection(&mutex->lock);

    void qemu_mutex_lock_impl(QemuMutex *mutex, const char *file,
const int line)
        qemu_mutex_pre_lock(mutex, file, line);
-    AcquireSRWLockExclusive(&mutex->lock);
+    EnterCriticalSection(&mutex->lock);
        qemu_mutex_post_lock(mutex, file, line);

@@ -69,7 +69,7 @@ int qemu_mutex_trylock_impl(QemuMutex *mutex,
const char *file, const int line)
        int owned;

-    owned = TryAcquireSRWLockExclusive(&mutex->lock);
+    owned = TryEnterCriticalSection(&mutex->lock);there
        if (owned) {
            qemu_mutex_post_lock(mutex, file, line);
            return 0;
@@ -81,7 +81,7 @@ void qemu_mutex_unlock_impl(QemuMutex *mutex,
const char *file, const int line)
        qemu_mutex_pre_unlock(mutex, file, line);
-    ReleaseSRWLockExclusive(&mutex->lock);
+    LeaveCriticalSection(&mutex->lock);

    void qemu_rec_mutex_init(QemuRecMutex *mutex)
@@ -141,11 +141,12 @@ void qemu_cond_broadcast(QemuCond *cond)

-void qemu_cond_wait_impl(QemuCond *cond, QemuMutex *mutex, const
char *file, const int line)
+void qemu_cond_wait_impl(QemuCond *cond, QemuMutex *mutex, const
char *file,
+                         const int line)
        qemu_mutex_pre_unlock(mutex, file, line);
-    SleepConditionVariableSRW(&cond->var, &mutex->lock,
+    SleepConditionVariableCS(&cond->var, &mutex->lock, INFINITE);
        qemu_mutex_post_lock(mutex, file, line);


Do you have any idea of what's happening?


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