[RFC PATCH 01/10] hw/ide/piix: Check for presence of ISABus before using it

[Bernhard Beschow <shentey@gmail.com>]

This is an alternative solution to commit
9405d87be25db6dff4d7b5ab48a81bbf6d083e47 'hw/ide: Fix crash when plugging a
piix3-ide device into the x-remote machine' which allows for cleaning up the
ISA API while keeping PIIX IDE functions user-createable for an arbitrarily
long deprecation period.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
---
 hw/ide/piix.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/hw/ide/piix.c b/hw/ide/piix.c
index 9a9b28078e..e8f3abc4b5 100644
--- a/hw/ide/piix.c
+++ b/hw/ide/piix.c
@@ -136,6 +136,17 @@ static int pci_piix_init_ports(PCIIDEState *d)
     };
     int i, ret;
 
+    {
+        ISABus *isa_bus;
+        bool ambiguous;
+
+        isa_bus = ISA_BUS(object_resolve_path_type("", TYPE_ISA_BUS,
+                                                   &ambiguous));
+        if (!isa_bus || ambiguous) {
+            return -ENODEV;
+        }
+    }
+
     for (i = 0; i < 2; i++) {
         ide_bus_init(&d->bus[i], sizeof(d->bus[i]), DEVICE(d), i, 2);
         ret = ide_init_ioport(&d->bus[i], NULL, port_info[i].iobase,
-- 
2.36.1