diff options
| -rw-r--r-- | arch/x86/pci/i386.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c index b22d13b0c71d..a672f12afe34 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) |