From ece15babfa514e06118f62f4df2c757d6209f4f0 Mon Sep 17 00:00:00 2001
From: Marcelo Tosatti <mtosatti@redhat.com>
Date: Wed, 30 Apr 2008 13:23:54 -0300
Subject: [PATCH] KVM: PIT: support mode 4
The in-kernel PIT emulation ignores pending timers if operating under
mode 4, which for example DragonFlyBSD uses (and Plan9 too, apparently).
Mode 4 seems to be similar to one-shot mode, other than the fact that it
starts counting after the next CLK pulse once programmed, while mode 1
starts counting immediately, so add a FIXME to enhance precision.
Fixes sourceforge bug 1952988.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Acked-by: Sheng Yang <sheng.yang@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
---
arch/x86/kvm/i8254.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 4c943eabacc39..3324d90038e43 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -288,6 +288,8 @@ static void pit_load_count(struct kvm *kvm, int channel, u32 val)
* mode 1 is one shot, mode 2 is period, otherwise del timer */
switch (ps->channels[0].mode) {
case 1:
+ /* FIXME: enhance mode 4 precision */
+ case 4:
create_pit_timer(&ps->pit_timer, val, 0);
break;
case 2:
--
2.30.2