diff options
authorZachary Amsden <zach@vmware.com>2007-03-05 00:30:39 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-03-05 07:57:52 -0800
commite30fab3ad34aa8bfb55c9f0337d4a92a0595f41f (patch)
parent[PATCH] vmi: paravirt drop udelay op (diff)
[PATCH] vmi: pit override
The time_init_hook in paravirt-ops no longer functions in the correct manner after the integration of the hrtimers code. The problem is that now the call path for time initialization is: time_init : late_time_init = hpet_time_init; late_time_init -> hpet_time_init: setup_pit_timer (BAD) do_time_init --> (via paravirt.h) time_init_hook --> (via arch_hooks.h) time_init_hook (in SUBARCH/setup.c) If this isn't confusing enough, the paravirt case goes through an indirect function pointer in the paravirt-ops table. The problem is, by the time the paravirt hook is called, the pit timer is already enabled. But paravirt guests have their own timer, and don't want to use the PIT. Rather than intensify the struggle for power going on here, just make it all nice and simple and just unconditionally do all timer setup in the late_time_init hook. This also has the advantage of enabling timers in the same place in all code paths, so everyone has the same bugs and we don't have outliers who break other code because they turn on timer too early or too late. So the paravirt-ops time init function is now by default hpet_time_init, which is the time init function used for native hardware. Paravirt guests have the chance to override this when they setup the paravirt-ops table, and should need no change. Signed-off-by: Zachary Amsden <zach@vmware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
4 files changed, 18 insertions, 7 deletions
diff --git a/arch/i386/kernel/paravirt.c b/arch/i386/kernel/paravirt.c
index 871448db1425..2ec331e03fa9 100644
--- a/arch/i386/kernel/paravirt.c
+++ b/arch/i386/kernel/paravirt.c
@@ -494,7 +494,7 @@ struct paravirt_ops paravirt_ops = {
.memory_setup = machine_specific_memory_setup,
.get_wallclock = native_get_wallclock,
.set_wallclock = native_set_wallclock,
- .time_init = time_init_hook,
+ .time_init = hpet_time_init,
.init_IRQ = native_init_IRQ,
.cpuid = native_cpuid,
diff --git a/arch/i386/kernel/time.c b/arch/i386/kernel/time.c
index a5350059557a..ccd3734edb8f 100644
--- a/arch/i386/kernel/time.c
+++ b/arch/i386/kernel/time.c
@@ -262,14 +262,22 @@ void notify_arch_cmos_timer(void)
extern void (*late_time_init)(void);
/* Duplicate of time_init() below, with hpet_enable part added */
-static void __init hpet_time_init(void)
+void __init hpet_time_init(void)
if (!hpet_enable())
- do_time_init();
+ time_init_hook();
+ * This is called directly from init code; we must delay timer setup in the
+ * HPET case as we can't make the decision to turn on HPET this early in the
+ * boot process.
+ *
+ * The chosen time_init function will usually be hpet_time_init, above, but
+ * in the case of virtual hardware, an alternative function may be substituted.
+ */
void __init time_init(void)
- late_time_init = hpet_time_init;
+ late_time_init = choose_time_init();
diff --git a/include/asm-i386/paravirt.h b/include/asm-i386/paravirt.h
index 1e4226a85263..f8319cae2ac5 100644
--- a/include/asm-i386/paravirt.h
+++ b/include/asm-i386/paravirt.h
@@ -186,9 +186,9 @@ static inline int set_wallclock(unsigned long nowtime)
return paravirt_ops.set_wallclock(nowtime);
-static inline void do_time_init(void)
+static inline void (*choose_time_init(void))(void)
- return paravirt_ops.time_init();
+ return paravirt_ops.time_init;
/* The paravirtualized CPUID instruction. */
diff --git a/include/asm-i386/time.h b/include/asm-i386/time.h
index ea8065af825a..eac011366dc2 100644
--- a/include/asm-i386/time.h
+++ b/include/asm-i386/time.h
@@ -28,13 +28,16 @@ static inline int native_set_wallclock(unsigned long nowtime)
return retval;
+extern void (*late_time_init)(void);
+extern void hpet_time_init(void);
#include <asm/paravirt.h>
#else /* !CONFIG_PARAVIRT */
#define get_wallclock() native_get_wallclock()
#define set_wallclock(x) native_set_wallclock(x)
-#define do_time_init() time_init_hook()
+#define choose_time_init() hpet_time_init
#endif /* CONFIG_PARAVIRT */