[Qemu-devel] Patch: PIC-i8259 does not work in single mode

[Bernhard Kauer <kauer@os.inf.tu-dresden.de>]

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The PIC-i8259 does not work in single mode, where only the master PIC is used.
The attached patch fixes the initialization part for single mode.

    Bernhard Kauer

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Index: i8259.c
===================================================================
RCS file: /sources/qemu/qemu/hw/i8259.c,v
retrieving revision 1.20
diff -u -r1.20 i8259.c
--- i8259.c	24 Jan 2007 01:47:51 -0000	1.20
+++ i8259.c	26 Mar 2007 17:01:18 -0000
@@ -44,6 +44,7 @@
     uint8_t rotate_on_auto_eoi;
     uint8_t special_fully_nested_mode;
     uint8_t init4; /* true if 4 byte init */
+    uint8_t single_mode; /* true if slave pic is not initialized */
     uint8_t elcr; /* PIIX edge/trigger selection*/
     uint8_t elcr_mask;
     PicState2 *pics_state;
@@ -278,6 +279,7 @@
     s->rotate_on_auto_eoi = 0;
     s->special_fully_nested_mode = 0;
     s->init4 = 0;
+    s->single_mode = 0;
     /* Note: ELCR is not reset */
 }
 
@@ -298,8 +300,7 @@
             s->pics_state->irq_request(s->pics_state->irq_request_opaque, 0);
             s->init_state = 1;
             s->init4 = val & 1;
-            if (val & 0x02)
-                hw_error("single mode not supported");
+            s->single_mode = val & 2;
             if (val & 0x08)
                 hw_error("level sensitive irq not supported");
         } else if (val & 0x08) {
@@ -356,7 +357,7 @@
             break;
         case 1:
             s->irq_base = val & 0xf8;
-            s->init_state = 2;
+            s->init_state = s->single_mode && s->init4 ? 3 : 2;
             break;
         case 2:
             if (s->init4) {
@@ -468,6 +469,7 @@
     qemu_put_8s(f, &s->rotate_on_auto_eoi);
     qemu_put_8s(f, &s->special_fully_nested_mode);
     qemu_put_8s(f, &s->init4);
+    qemu_put_8s(f, &s->single_mode);
     qemu_put_8s(f, &s->elcr);
 }
 
@@ -492,6 +494,7 @@
     qemu_get_8s(f, &s->rotate_on_auto_eoi);
     qemu_get_8s(f, &s->special_fully_nested_mode);
     qemu_get_8s(f, &s->init4);
+    qemu_get_8s(f, &s->single_mode);
     qemu_get_8s(f, &s->elcr);
     return 0;
 }