[Qemu-devel] [RFC PATCH 2/2] hw/alpha/dp264: Disable the Super I/O parallel port

["Philippe Mathieu-Daudé" <f4bug@amsat.org>]

The 3BCh I/O address was used by "Parallel Ports which were
incorporated on to Video Cards" and "has now reappeared as
an option for Parallel Ports integrated onto motherboards,
upon which their configuration can be changed using BIOS."

The real PALcode is expected to configure the Super I/O and
disable the parallel port, to allow the 3c0-3cf range to be
assigned to the Cirrus VGA.

This fixes an issue introduced in a4cb773928e where the SIO
bind the parallel port in the address range used by the VGA
device, resulting in overlap:

(qemu) info mtree
address-space: memory
  0000000000000000-ffffffffffffffff (prio 0, i/o): system
    00000801fc000000-00000801fdffffff (prio 0, i/o): pci0-io
      ...
      00000801fc0003b4-00000801fc0003b5 (prio 0, i/o): vga
      00000801fc0003ba-00000801fc0003ba (prio 0, i/o): vga
      00000801fc0003bc-00000801fc0003c3 (prio 0, i/o): parallel
                                    ^^^                ^^^^^^^^
      00000801fc0003c0-00000801fc0003cf (prio 0, i/o): vga
                   ^^^
      00000801fc0003d4-00000801fc0003d5 (prio 0, i/o): vga
      00000801fc0003da-00000801fc0003da (prio 0, i/o): vga
      ...

Reported-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 hw/alpha/dp264.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/hw/alpha/dp264.c b/hw/alpha/dp264.c
index 80b987f7fb..87504add8e 100644
--- a/hw/alpha/dp264.c
+++ b/hw/alpha/dp264.c
@@ -58,6 +58,7 @@ static void clipper_init(MachineState *machine)
     AlphaCPU *cpus[4];
     PCIBus *pci_bus;
     ISABus *isa_bus;
+    DeviceState *superio;
     qemu_irq rtc_irq;
     long size, i;
     char *palcode_filename;
@@ -95,7 +96,10 @@ static void clipper_init(MachineState *machine)
     isa_create_simple(isa_bus, "i82374");
 
     /* Super I/O */
-    isa_create_simple(isa_bus, TYPE_SMC37C669_SUPERIO);
+    superio = DEVICE(isa_create(isa_bus, TYPE_SMC37C669_SUPERIO));
+    /* Real PALcode configures the Super I/O and disable the parallel port */
+    qdev_prop_set_bit(superio, "parallel", false);
+    qdev_init_nofail(superio);
 
     /* IDE disk setup.  */
     {
-- 
2.17.1