port-i386/38729: ACPI kernel booted under qemu cannot detect devices

["Jared D. McNeill" <jmcneill%invisible.ca@localhost>]

The attached patch fixes PCI bus detection issues in qemu with ACPI
enabled. It should apply cleanly to 5.0, and amd64 machdep will probably
need the same treatment but I cannot test.

Cheers,
Jared

Index: i386/i386/mainbus.c
===================================================================
RCS file: /cvsroot/src/sys/arch/i386/i386/mainbus.c,v
retrieving revision 1.77
diff -u -p -r1.77 mainbus.c
--- i386/i386/mainbus.c 18 May 2008 02:06:14 -0000      1.77
+++ i386/i386/mainbus.c 24 Mar 2009 13:38:35 -0000
@@ -319,6 +319,8 @@ mainbus_attach(struct device *parent, st
         */
 #if NPCI > 0
        if (pci_mode != 0) {
+               int npcibus = 0;
+
                mba.mba_pba.pba_iot = X86_BUS_SPACE_IO;
                mba.mba_pba.pba_memt = X86_BUS_SPACE_MEM;
                mba.mba_pba.pba_dmat = &pci_bus_dma_tag;
@@ -328,16 +330,18 @@ mainbus_attach(struct device *parent, st
                mba.mba_pba.pba_bus = 0;
                mba.mba_pba.pba_bridgetag = NULL;
 #if NACPI > 0 && defined(ACPI_SCANPCI)
-               if (mpacpi_active)
-                       mpacpi_scan_pci(self, &mba.mba_pba, pcibusprint);
-               else
+               if (npcibus == 0 && mpacpi_active)
+                       npcibus = mpacpi_scan_pci(self, &mba.mba_pba,
+                           pcibusprint);
 #endif
 #if defined(MPBIOS) && defined(MPBIOS_SCANPCI)
-               if (mpbios_scanned != 0)
-                       mpbios_scan_pci(self, &mba.mba_pba, pcibusprint);
-               else
-#endif
-               config_found_ia(self, "pcibus", &mba.mba_pba, pcibusprint);
+               if (npcibus == 0 && mpbios_scanned != 0)
+                       npcibus = mpbios_scan_pci(self, &mba.mba_pba,
+                           pcibusprint);
+#endif
+               if (npcibus == 0)
+                       config_found_ia(self, "pcibus", &mba.mba_pba,
+                           pcibusprint);
 #if NACPI > 0
                if (mp_verbose)
                        acpi_pci_link_state();
Index: x86/x86/mpacpi.c
===================================================================
RCS file: /cvsroot/src/sys/arch/x86/x86/mpacpi.c,v
retrieving revision 1.69.4.1
diff -u -p -r1.69.4.1 mpacpi.c
--- x86/x86/mpacpi.c    16 Jan 2009 21:35:43 -0000      1.69.4.1
+++ x86/x86/mpacpi.c    24 Mar 2009 13:38:35 -0000
@@ -1165,7 +1165,7 @@ int
 mpacpi_scan_pci(struct device *self, struct pcibus_attach_args *pba,
                cfprint_t print)
 {
-       int i;
+       int i, cnt = 0;
        struct mp_bus *mpb;
        struct pci_attach_args;
 
@@ -1176,9 +1176,10 @@ mpacpi_scan_pci(struct device *self, str
                if (!strcmp(mpb->mb_name, "pci") && mpb->mb_configured == 0) {
                        pba->pba_bus = i;
                        config_found_ia(self, "pcibus", pba, print);
+                       ++cnt;
                }
        }
-       return 0;
+       return cnt;
 }
 
 #endif
Index: x86/x86/mpbios.c
===================================================================
RCS file: /cvsroot/src/sys/arch/x86/x86/mpbios.c,v
retrieving revision 1.47
diff -u -p -r1.47 mpbios.c
--- x86/x86/mpbios.c    26 Aug 2008 12:04:18 -0000      1.47
+++ x86/x86/mpbios.c    24 Mar 2009 13:38:35 -0000
@@ -1203,7 +1203,7 @@ int
 mpbios_scan_pci(struct device *self, struct pcibus_attach_args *pba,
                cfprint_t print)
 {
-       int i;
+       int i, cnt = 0;
        struct mp_bus *mpb;
        struct pci_attach_args;
 
@@ -1214,9 +1214,10 @@ mpbios_scan_pci(struct device *self, str
                if (!strcmp(mpb->mb_name, "pci") && mpb->mb_configured == 0) {
                        pba->pba_bus = i;
                        config_found_ia(self, "pcibus", pba, print);
+                       ++cnt;
                }
        }
-       return 0;
+       return cnt;
 }
 
 #endif