xen: fix legacy irq setup, make ioapic-less machines work.

If the machine has no IO APICs, then just allocate a set of legacy
interrupts.

[ Impact: fix Xen compatibility with old machines ]

Signed-off-by: Gerd Hoffmann <kraxel@xeni.home.kraxel.org>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

diff --git a/arch/x86/xen/pci.c b/arch/x86/xen/pci.c
index 76c35b854bb8c27a5e38b9817557f84dd73f4c4d..07b59fec12afdd7658cc823ba557f264315e1220 100644 (file)
--- a/arch/x86/xen/pci.c
+++ b/arch/x86/xen/pci.c
@@ -66,8 +66,14 @@ void __init xen_setup_pirqs(void)
 {
        int irq;
 
+       if (0 == nr_ioapics) {
+               for (irq = 0; irq < NR_IRQS_LEGACY; irq++)
+                       xen_allocate_pirq(irq, "xt-pic");
+               return;
+       }
+
        /* Pre-allocate legacy irqs */
-       for (irq=0; irq < NR_IRQS_LEGACY; irq++) {
+       for (irq = 0; irq < NR_IRQS_LEGACY; irq++) {
                int trigger, polarity;
 
                if (acpi_get_override_irq(irq, &trigger, &polarity) == -1)