[Qemu-devel] [PATCH] i8259: Do not clear level-triggered lines in IRR on init

[Jan Kiszka]

When an input line is handled as level-triggered, it will immediately
raise an IRQ on the output of a PIC again that goes through an init
reset. So only clear the edge-triggered inputs from IRR in that
scenario.

Signed-off-by: Jan Kiszka <jan.kis...@siemens.com>
---
 hw/i8259.c        |    2 +-
 hw/i8259_common.c |    2 +-
 hw/kvm/i8259.c    |    2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/hw/i8259.c b/hw/i8259.c
index 3005ce2..264bfc6 100644
--- a/hw/i8259.c
+++ b/hw/i8259.c
@@ -231,8 +231,8 @@ static void pic_reset(DeviceState *dev)
 {
     PICCommonState *s = DO_UPCAST(PICCommonState, dev.qdev, dev);
 
-    pic_init_reset(s);
     s->elcr = 0;
+    pic_init_reset(s);
 }
 
 static void pic_ioport_write(void *opaque, target_phys_addr_t addr64,
diff --git a/hw/i8259_common.c b/hw/i8259_common.c
index e515876..37aeee2 100644
--- a/hw/i8259_common.c
+++ b/hw/i8259_common.c
@@ -28,7 +28,7 @@
 void pic_reset_common(PICCommonState *s)
 {
     s->last_irr = 0;
-    s->irr = 0;
+    s->irr &= s->elcr;
     s->imr = 0;
     s->isr = 0;
     s->priority_add = 0;
diff --git a/hw/kvm/i8259.c b/hw/kvm/i8259.c
index 64bb5c2..298d9ca 100644
--- a/hw/kvm/i8259.c
+++ b/hw/kvm/i8259.c
@@ -84,8 +84,8 @@ static void kvm_pic_reset(DeviceState *dev)
 {
     PICCommonState *s = DO_UPCAST(PICCommonState, dev.qdev, dev);
 
-    pic_reset_common(s);
     s->elcr = 0;
+    pic_reset_common(s);
 
     kvm_pic_put(s);
 }
-- 
1.7.3.4