qemu hangs when an i386 Linux host resumes from suspend (swsusp2),
because the host's TSC is reset to a value lower than it was before
the suspend.
Although this is a bug in the host OS, the attached patch (originally
from John Coiner) is simple and makes qemu more resilient to weird
host tick counter behavior.
--Ed
diff -BurN qemu-snapshot-2006-03-27_23.orig/vl.c qemu-snapshot-2006-03-27_23/vl.c
--- qemu-snapshot-2006-03-27_23.orig/vl.c 2006-04-01 18:38:27.000000000 +0000
+++ qemu-snapshot-2006-03-27_23/vl.c 2006-04-01 18:41:36.000000000 +0000
@@ -579,14 +579,21 @@
#error unsupported CPU
#endif
-static int64_t cpu_ticks_offset;
-static int cpu_ticks_enabled;
+static int64_t cpu_ticks_prev;
+static int64_t cpu_ticks_offset;
+static int cpu_ticks_enabled;
static inline int64_t cpu_get_ticks(void)
{
if (!cpu_ticks_enabled) {
return cpu_ticks_offset;
} else {
+ int64_t ticks;
+ ticks = cpu_get_real_ticks();
+ if (cpu_ticks_prev > ticks) {
+ cpu_ticks_offset += cpu_ticks_prev - ticks;
+ }
+ cpu_ticks_prev = ticks;
- return cpu_get_real_ticks() + cpu_ticks_offset;
+ return ticks + cpu_ticks_offset;
}
}
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