Commit ece15bab authored Apr 30, 2008 by Marcelo Tosatti Committed by Avi Kivity May 04, 2008

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>

parent dc7457ea

arch/x86/kvm/i8254.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -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: