summaryrefslogtreecommitdiff
path: root/arch/x86/pci
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/pci')
-rw-r--r--arch/x86/pci/i386.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
index 52e62e57fedd..5da8792b48a4 100644
--- a/arch/x86/pci/i386.c
+++ b/arch/x86/pci/i386.c
@@ -282,6 +282,15 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
return -EINVAL;
prot = pgprot_val(vma->vm_page_prot);
+
+ /*
+ * Return error if pat is not enabled and write_combine is requested.
+ * Caller can followup with UC MINUS request and add a WC mtrr if there
+ * is a free mtrr slot.
+ */
+ if (!pat_enabled && write_combine)
+ return -EINVAL;
+
if (pat_enabled && write_combine)
prot |= _PAGE_CACHE_WC;
else if (pat_enabled || boot_cpu_data.x86 > 3)