File 0023-linux-user-Run-multi-threaded-code-.patch of Package qemu

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File 0023-linux-user-Run-multi-threaded-code-.patch of Package qemu (Revision 28d781b99307637791ffbcedd42d25c4)

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From 871faba46546dc6779367f54e19cf047109d798b Mon Sep 17 00:00:00 2001
From: Alexander Graf <agraf@suse.de>
Date: Tue, 10 Jul 2012 20:40:55 +0200
Subject: [PATCH] linux-user: Run multi-threaded code on a single core

Running multi-threaded code can easily expose some of the fundamental
breakages in QEMU's design. It's just not a well supported scenario.

So if we pin the whole process to a single host CPU, we guarantee that
we will never have concurrent memory access actually happen. We can still
get scheduled away at any time, so it's no complete guarantee, but apparently
it reduces the odds well enough to get my test cases to pass.

This gets Java 1.7 working for me again on my test box.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 linux-user/syscall.c |    9 +++++++++
 1 Datei geändert, 9 Zeilen hinzugefügt(+)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index d62e9e6..5295afb 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -4400,6 +4400,15 @@ static int do_fork(CPUArchState *env, unsigned int flags, abi_ulong newsp,
         if (nptl_flags & CLONE_SETTLS)
             cpu_set_tls (new_env, newtls);
 
+        /* agraf: Pin ourselves to a single CPU when running multi-threaded.
+           This turned out to improve stability for me. */
+        {
+            cpu_set_t mask;
+            CPU_ZERO(&mask);
+            CPU_SET(0, &mask);
+            sched_setaffinity(0, sizeof(mask), &mask);
+        }
+
         /* Grab a mutex so that thread setup appears atomic.  */
         pthread_mutex_lock(&clone_lock);

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File 0023-linux-user-Run-multi-threaded-code-.patch of Package qemu (Revision 28d781b99307637791ffbcedd42d25c4)

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