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qemu/0020-linux-user-Run-multi-threaded-code-.patch
Bruce Rogers 9633a9b62c Accepting request 210801 from home:bfrogers:branches:Virtualization
Adjust for recently fixed acpica package, Do a better? work around for roms/Makefile issue. Rework changes file for suitability for openSUSE:Factory checkin.

OBS-URL: https://build.opensuse.org/request/show/210801
OBS-URL: https://build.opensuse.org/package/show/Virtualization/qemu?expand=0&rev=170
2013-12-13 14:49:46 +00:00

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From 5a24d8e40ae04bbc4cb20472e16c86f5b587d1cb 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 files changed, 9 insertions(+), 0 deletions(-)
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 5113d22..7be6873 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -4432,6 +4432,15 @@ 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);