Index: qemu/Makefile.target
===================================================================
--- qemu.orig/Makefile.target
+++ qemu/Makefile.target
@@ -500,7 +500,7 @@ endif #CONFIG_BSD_USER
 # System emulator target
 ifndef CONFIG_USER_ONLY
 
-OBJS=vl.o osdep.o monitor.o pci.o loader.o isa_mmio.o machine.o
+OBJS=vl.o qemu-thread.o osdep.o monitor.o pci.o loader.o isa_mmio.o machine.o
 # virtio has to be here due to weird dependency between PCI and virtio-net.
 # need to fix this properly
 OBJS+=virtio.o virtio-blk.o virtio-balloon.o virtio-net.o virtio-console.o
Index: qemu/vl.c
===================================================================
--- qemu.orig/vl.c
+++ qemu/vl.c
@@ -36,6 +36,7 @@
 #include "gdbstub.h"
 #include "qemu-timer.h"
 #include "qemu-char.h"
+#include "qemu-thread.h"
 #include "cache-utils.h"
 #include "block.h"
 #include "audio/audio.h"
@@ -263,6 +264,8 @@ static QEMUTimer *nographic_timer;
 
 uint8_t qemu_uuid[16];
 
+QemuMutex qemu_global_mutex;
+
 /***********************************************************/
 /* x86 ISA bus support */
 
@@ -3650,7 +3653,14 @@ void main_loop_wait(int timeout)
         slirp_select_fill(&nfds, &rfds, &wfds, &xfds);
     }
 #endif
+
+    /*
+     * main_loop_wait() *must* not assume any global state is consistent across
+     * select() invocations.
+     */
+    qemu_mutex_unlock(&qemu_global_mutex);
     ret = select(nfds + 1, &rfds, &wfds, &xfds, &tv);
+    qemu_mutex_lock(&qemu_global_mutex);
     if (ret > 0) {
         IOHandlerRecord **pioh;
 
@@ -3708,6 +3718,9 @@ static int main_loop(void)
 #endif
     CPUState *env;
 
+    qemu_mutex_init(&qemu_global_mutex);
+    qemu_mutex_lock(&qemu_global_mutex);
+
     cur_cpu = first_cpu;
     next_cpu = cur_cpu->next_cpu ?: first_cpu;
     for(;;) {
Index: qemu/qemu-thread.c
===================================================================
--- /dev/null
+++ qemu/qemu-thread.c
@@ -0,0 +1,99 @@
+#include <errno.h>
+#include <time.h>
+#include <signal.h>
+#include "qemu-thread.h"
+
+int qemu_mutex_init(QemuMutex *mutex)
+{
+    return pthread_mutex_init(&mutex->lock, NULL);
+}
+
+void qemu_mutex_lock(QemuMutex *mutex)
+{
+    pthread_mutex_lock(&mutex->lock);
+}
+
+int qemu_mutex_trylock(QemuMutex *mutex)
+{
+    return pthread_mutex_trylock(&mutex->lock);
+}
+
+static void add_to_timespec(struct timespec *ts, unsigned int msecs)
+{
+    ts->tv_sec = ts->tv_sec + (long)(msecs / 1000);
+    ts->tv_nsec = (ts->tv_nsec + ((long)msecs % 1000) * 1000000);
+    if (ts->tv_nsec >= 1000000000) {
+        ts->tv_nsec -= 1000000000;
+        ts->tv_sec++;
+    }
+}
+
+int qemu_mutex_timedlock(QemuMutex *mutex, unsigned int msecs)
+{
+    struct timespec ts;
+
+    clock_gettime(CLOCK_REALTIME, &ts);
+    add_to_timespec(&ts, msecs);
+
+    return pthread_mutex_timedlock(&mutex->lock, &ts);
+}
+
+void qemu_mutex_unlock(QemuMutex *mutex)
+{
+    pthread_mutex_unlock(&mutex->lock);
+}
+
+void qemu_cond_init(QemuCond *cond)
+{
+    pthread_cond_init(&cond->cond, NULL);
+}
+
+void qemu_cond_signal(QemuCond *cond)
+{
+    pthread_cond_signal(&cond->cond);
+}
+
+void qemu_cond_broadcast(QemuCond *cond)
+{
+    pthread_cond_broadcast(&cond->cond);
+}
+
+int qemu_cond_wait(QemuCond *cond, QemuMutex *mutex)
+{
+    return pthread_cond_wait(&cond->cond, &mutex->lock);
+}
+
+int qemu_cond_timedwait(QemuCond *cond, QemuMutex *mutex, unsigned int msecs)
+{
+    struct timespec ts;
+
+    clock_gettime(CLOCK_REALTIME, &ts);
+    add_to_timespec(&ts, msecs);
+
+    return pthread_cond_timedwait(&cond->cond, &mutex->lock, &ts);
+}
+
+int qemu_thread_create(QemuThread *thread,
+                       void *(*start_routine)(void*),
+                       void *arg)
+{
+    return pthread_create(&thread->thread, NULL, start_routine, arg);
+}
+
+int qemu_thread_signal(QemuThread *thread, int sig)
+{
+    if (thread->thread != 0)
+        return pthread_kill(thread->thread, sig);
+    return -1; /* XXX: ESCHR */
+}
+
+void qemu_thread_self(QemuThread *thread)
+{
+    thread->thread = pthread_self();
+}
+
+int qemu_thread_equal(QemuThread *thread1, QemuThread *thread2)
+{
+   return (thread1->thread == thread2->thread);
+}
+
Index: qemu/qemu-thread.h
===================================================================
--- /dev/null
+++ qemu/qemu-thread.h
@@ -0,0 +1,38 @@
+#include "semaphore.h"
+#include "pthread.h"
+
+struct QemuMutex {
+    pthread_mutex_t lock;
+};
+
+struct QemuCond {
+    pthread_cond_t cond;
+};
+
+struct QemuThread {
+    pthread_t thread;
+};
+
+typedef struct QemuMutex QemuMutex;
+typedef struct QemuCond QemuCond;
+typedef struct QemuThread QemuThread;
+
+int qemu_mutex_init(QemuMutex *mutex);
+void qemu_mutex_lock(QemuMutex *mutex);
+int qemu_mutex_trylock(QemuMutex *mutex);
+int qemu_mutex_timedlock(QemuMutex *mutex, unsigned int msecs);
+void qemu_mutex_unlock(QemuMutex *mutex);
+
+void qemu_cond_init(QemuCond *cond);
+void qemu_cond_signal(QemuCond *cond);
+void qemu_cond_broadcast(QemuCond *cond);
+int qemu_cond_wait(QemuCond *cond, QemuMutex *mutex);
+int qemu_cond_timedwait(QemuCond *cond, QemuMutex *mutex, unsigned int msecs);
+
+int qemu_thread_create(QemuThread *thread,
+                       void *(*start_routine)(void*),
+                       void *arg);
+int qemu_thread_signal(QemuThread *thread, int sig);
+void qemu_thread_self(QemuThread *thread);
+int qemu_thread_equal(QemuThread *thread1, QemuThread *thread2);
+

--