[PATCH v3 20/28] i8259.c: properly cascade secondary i8259 from primary i8259

[Mark Cave-Ayland <mark.caveayland@xxxxxxxxxxx>]

Currently the cascaded output from the secondary i8259 is returned directly in
the pass_irqs[] array, instead of being connected to the relevant input of the
primary i8259.

This is a bug fix since in a cascaded configuration on real hardware it is
possible (although unlikely) that the cascaded input from the secondary i8259
can be masked on the primary i8259.

Signed-off-by: Mark Cave-Ayland <mark.caveayland@xxxxxxxxxxx>
---
 hw/intc/i8259.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/hw/intc/i8259.c b/hw/intc/i8259.c
index fe524efbce..d713795ae0 100644
--- a/hw/intc/i8259.c
+++ b/hw/intc/i8259.c
@@ -504,6 +504,11 @@ static void i8259_pic_realize(DeviceState *dev, Error 
**errp)
     }
 
     for (i = 0; i < 8; i++) {
+        /* Cascaded input is not usable */
+        if (i == 2) {
+            continue;
+        }
+
         s->pass_irqs[i] = qdev_get_gpio_in(pri_dev, i);
     }
 
@@ -519,7 +524,8 @@ static void i8259_pic_realize(DeviceState *dev, Error 
**errp)
     }
 
     /* Wire up secondary cascade */
-    qdev_connect_gpio_out(sec_dev, 0, s->pass_irqs[2]);
+    qdev_connect_gpio_out(sec_dev, 0,
+                          qdev_get_gpio_in(pri_dev, 2));
 
     for (i = 8; i < ISA_NUM_IRQS; i++) {
         s->pass_irqs[i] = qdev_get_gpio_in(sec_dev, i - 8);
-- 
2.43.0