x86/PCI: build failure at x86/kernel/pci-dma.c with !CONFIG_PCI

On Thu, Oct 23, 2008 at 04:09:52PM -0700, Alexander Beregalov wrote:
> arch/x86/kernel/built-in.o: In function `iommu_setup':
> pci-dma.c:(.init.text+0x36ad): undefined reference to `forbid_dac'
> pci-dma.c:(.init.text+0x36cc): undefined reference to `forbid_dac'
> pci-dma.c:(.init.text+0x3711): undefined reference to `forbid_dac

This patch partially reverts a patch to add IOMMU support to ia64.  The
forbid_dac variable was incorrectly moved to quirks.c, which isn't built
when PCI is disabled.
Tested-by: N"Alexander Beregalov" <a.beregalov@gmail.com>
Acked-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: NFenghua Yu <fenghua.yu@intel.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

arch/ia64/include/asm/iommu.h

@@ -11,6 +11,5 @@ extern int force_iommu, no_iommu;
 extern int iommu_detected;
 extern void iommu_dma_init(void);
 extern void machvec_init(const char *name);
-extern int forbid_dac;
 
 #endif

arch/ia64/kernel/pci-dma.c

@@ -89,13 +89,6 @@ int iommu_dma_supported(struct device *dev, u64 mask)
 {
 	struct dma_mapping_ops *ops = get_dma_ops(dev);
 
-#ifdef CONFIG_PCI
-	if (mask > 0xffffffff && forbid_dac > 0) {
-		dev_info(dev, "Disallowing DAC for device\n");
-		return 0;
-	}
-#endif
-
 	if (ops->dma_supported_op)
 		return ops->dma_supported_op(dev, mask);
 

arch/x86/include/asm/iommu.h

@@ -7,7 +7,6 @@ extern struct dma_mapping_ops nommu_dma_ops;
 extern int force_iommu, no_iommu;
 extern int iommu_detected;
 extern int dmar_disabled;
-extern int forbid_dac;
 
 extern unsigned long iommu_nr_pages(unsigned long addr, unsigned long len);
 

arch/x86/kernel/pci-dma.c

@@ -9,6 +9,8 @@
 #include <asm/calgary.h>
 #include <asm/amd_iommu.h>
 
+static int forbid_dac __read_mostly;
+
 struct dma_mapping_ops *dma_ops;
 EXPORT_SYMBOL(dma_ops);
 
@@ -291,3 +293,17 @@ void pci_iommu_shutdown(void)
 }
 /* Must execute after PCI subsystem */
 fs_initcall(pci_iommu_init);
+
+#ifdef CONFIG_PCI
+/* Many VIA bridges seem to corrupt data for DAC. Disable it here */
+
+static __devinit void via_no_dac(struct pci_dev *dev)
+{
+	if ((dev->class >> 8) == PCI_CLASS_BRIDGE_PCI && forbid_dac == 0) {
+		printk(KERN_INFO "PCI: VIA PCI bridge detected."
+				 "Disabling DAC.\n");
+		forbid_dac = 1;
+	}
+}
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID, via_no_dac);
+#endif

drivers/pci/quirks.c

@@ -43,20 +43,6 @@ static void __devinit quirk_mellanox_tavor(struct pci_dev *dev)
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_MELLANOX,PCI_DEVICE_ID_MELLANOX_TAVOR,quirk_mellanox_tavor);
 DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_MELLANOX,PCI_DEVICE_ID_MELLANOX_TAVOR_BRIDGE,quirk_mellanox_tavor);
 
-/* Many VIA bridges seem to corrupt data for DAC. Disable it here */
-int forbid_dac __read_mostly;
-EXPORT_SYMBOL(forbid_dac);
-
-static __devinit void via_no_dac(struct pci_dev *dev)
-{
-	if ((dev->class >> 8) == PCI_CLASS_BRIDGE_PCI && forbid_dac == 0) {
-		dev_info(&dev->dev,
-			"VIA PCI bridge detected. Disabling DAC.\n");
-		forbid_dac = 1;
-	}
-}
-DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_VIA, PCI_ANY_ID, via_no_dac);
-
 /* Deal with broken BIOS'es that neglect to enable passive release,
    which can cause problems in combination with the 82441FX/PPro MTRRs */
 static void quirk_passive_release(struct pci_dev *dev)