Index: sys/arch/x86/acpi/acpi_machdep.c
===================================================================
RCS file: /cvsroot/src/sys/arch/x86/acpi/acpi_machdep.c,v
retrieving revision 1.36
diff -p -u -r1.36 acpi_machdep.c
--- sys/arch/x86/acpi/acpi_machdep.c	16 Oct 2023 17:27:02 -0000	1.36
+++ sys/arch/x86/acpi/acpi_machdep.c	22 Dec 2023 16:33:40 -0000
@@ -592,6 +592,10 @@ acpi_md_callback(struct acpi_softc *sc)
 #endif
 
 	acpimcfg_init(x86_bus_space_mem, &acpi_md_mcfg_ops);
+
+#ifdef PCI_NETBSD_CONFIGURE
+	mpacpi_configure_busses(sc);
+#endif
 }
 
 #ifndef XENPV
Index: sys/arch/x86/include/mpacpi.h
===================================================================
RCS file: /cvsroot/src/sys/arch/x86/include/mpacpi.h,v
retrieving revision 1.11
diff -p -u -r1.11 mpacpi.h
--- sys/arch/x86/include/mpacpi.h	23 May 2017 08:54:39 -0000	1.11
+++ sys/arch/x86/include/mpacpi.h	22 Dec 2023 16:33:40 -0000
@@ -7,6 +7,7 @@ struct pcibus_attach_args;
 
 int mpacpi_scan_apics(device_t, int *);
 int mpacpi_find_interrupts(void *);
+int mpacpi_configure_busses(void *);
 int mpacpi_pci_attach_hook(device_t, device_t,
 			   struct pcibus_attach_args *);
 
Index: sys/arch/x86/include/pci_machdep_common.h
===================================================================
RCS file: /cvsroot/src/sys/arch/x86/include/pci_machdep_common.h,v
retrieving revision 1.25
diff -p -u -r1.25 pci_machdep_common.h
--- sys/arch/x86/include/pci_machdep_common.h	1 Aug 2020 12:14:40 -0000	1.25
+++ sys/arch/x86/include/pci_machdep_common.h	22 Dec 2023 16:33:41 -0000
@@ -122,6 +122,7 @@ const struct evcnt *pci_intr_evcnt(pci_c
 void		*pci_intr_establish(pci_chipset_tag_t, pci_intr_handle_t,
 		    int, int (*)(void *), void *);
 void		pci_intr_disestablish(pci_chipset_tag_t, void *);
+void		pci_conf_interrupt(pci_chipset_tag_t, int, int, int, int, int *);
 
 #ifdef __HAVE_PCI_MSI_MSIX
 typedef enum {
Index: sys/arch/x86/pci/pci_intr_machdep.c
===================================================================
RCS file: /cvsroot/src/sys/arch/x86/pci/pci_intr_machdep.c,v
retrieving revision 1.51
diff -p -u -r1.51 pci_intr_machdep.c
--- sys/arch/x86/pci/pci_intr_machdep.c	1 Aug 2020 12:36:35 -0000	1.51
+++ sys/arch/x86/pci/pci_intr_machdep.c	22 Dec 2023 16:33:41 -0000
@@ -380,6 +380,12 @@ pci_intr_disestablish(pci_chipset_tag_t 
 	intr_disestablish(cookie);
 }
 
+void
+pci_conf_interrupt(pci_chipset_tag_t pc, int bus, int dev, int ipin, int swiz,
+    int *ilinep)
+{
+}
+
 #if NIOAPIC > 0
 #ifdef __HAVE_PCI_MSI_MSIX
 pci_intr_type_t
Index: sys/arch/x86/x86/mpacpi.c
===================================================================
RCS file: /cvsroot/src/sys/arch/x86/x86/mpacpi.c,v
retrieving revision 1.110
diff -p -u -r1.110 mpacpi.c
--- sys/arch/x86/x86/mpacpi.c	24 Mar 2023 12:25:28 -0000	1.110
+++ sys/arch/x86/x86/mpacpi.c	22 Dec 2023 16:33:41 -0000
@@ -72,6 +72,7 @@ __KERNEL_RCSID(0, "$NetBSD: mpacpi.c,v 1
 #include <dev/acpi/acpica.h>
 #include <dev/acpi/acpireg.h>
 #include <dev/acpi/acpivar.h>
+#include <dev/acpi/acpi_mcfg.h>
 
 #include <dev/cons.h>
 
@@ -1034,6 +1037,44 @@ mpacpi_pci_attach_hook(device_t parent, 
 #endif
 
 int
+mpacpi_configure_busses(void *self)
+{
+	struct acpi_softc *acpi = self;
+
+printf("MPACPI CONFIGURE BUSSES ? acpi = %p\n", acpi);
+
+#if NPCI > 0
+	struct mpacpi_pcibus *mpr;
+	struct mp_bus *mpb;
+
+	mpr = TAILQ_FIRST(&mpacpi_pcibusses);
+printf("MPACPI pcibus = %p\n", mpr);
+
+	if (mpr) {
+		ACPI_HANDLE hdl = devhandle_to_acpi(mpr->mpr_devhandle);
+		if (mp_verbose)
+			printf("MPACPI handle %s seg %d bus %d\n",
+				acpi_name(hdl),
+				mpr->mpr_seg,
+				mpr->mpr_bus);
+
+		if (mpr->mpr_bus < 0 || mpr->mpr_bus >= mpacpi_maxpci) {
+			printf("MPACPI bus number (%d) >= maxpci (%d)\n",
+				mpr->mpr_bus, mpacpi_maxpci);
+			return -1;
+		}
+
+		mpb = &mp_busses[mpr->mpr_bus]; /* XXX */
+
+		acpimcfg_configure_bus(mpb->mb_dev, mpb->mb_pci_chipset_tag,
+		    hdl, mpr->mpr_bus, CACHE_LINE_SIZE);
+	}
+#endif
+
+	return 0;
+}
+
+int
 mpacpi_findintr_linkdev(struct mp_intr_map *mip)
 {
 	int irq, line, pol, trig;