x86: ---
 arch/x86_64/mm/pat.c         |   36 ++++++++++++++++++++++++++++++++
 drivers/char/mem.c           |   48 ++++++++++++++++---------------------------
 include/asm-i386/pgtable.h   |    7 ++++++
 include/asm-x86_64/pgtable.h |    5 ++++
 4 files changed, 66 insertions(+), 30 deletions(-)

Index: linux/drivers/char/mem.c
===================================================================
--- linux.orig/drivers/char/mem.c
+++ linux/drivers/char/mem.c
@@ -42,36 +42,7 @@
  */
 static inline int uncached_access(struct file *file, unsigned long addr)
 {
-#if defined(__i386__)
-	/*
-	 * On the PPro and successors, the MTRRs are used to set
-	 * memory types for physical addresses outside main memory,
-	 * so blindly setting PCD or PWT on those pages is wrong.
-	 * For Pentiums and earlier, the surround logic should disable
-	 * caching for the high addresses through the KEN pin, but
-	 * we maintain the tradition of paranoia in this code.
-	 */
-	if (file->f_flags & O_SYNC)
-		return 1;
- 	return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||
-		  test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||
-		  test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||
-		  test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) )
-	  && addr >= __pa(high_memory);
-#elif defined(__x86_64__)
-	/* 
-	 * This is broken because it can generate memory type aliases,
-	 * which can cause cache corruptions
-	 * But it is only available for root and we have to be bug-to-bug
-	 * compatible with i386.
-	 */
-	if (file->f_flags & O_SYNC)
-		return 1;
-	/* same behaviour as i386. PAT always set to cached and MTRRs control the
-	   caching behaviour. 
-	   Hopefully a full PAT implementation will fix that soon. */	   
-	return 0;
-#elif defined(CONFIG_IA64)
+#if defined(CONFIG_IA64)
 	/*
 	 * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
 	 */
@@ -265,6 +236,21 @@ static inline int private_mapping_ok(str
 }
 #endif
 
+void __attribute__((weak))
+unmap_devmem(unsigned long pfn, unsigned long len)
+{
+	/* nothing. architectures can override. */
+}
+
+static void mmap_mem_close(struct vm_area_struct *vma)
+{
+	unmap_devmem(vma->vm_pgoff,  vma->vm_end - vma->vm_start);
+}
+
+static struct vm_operations_struct mmap_mem_ops = {
+	.close = mmap_mem_close
+};
+
 static int mmap_mem(struct file * file, struct vm_area_struct * vma)
 {
 	size_t size = vma->vm_end - vma->vm_start;
@@ -279,6 +265,8 @@ static int mmap_mem(struct file * file, 
 						 size,
 						 vma->vm_page_prot);
 
+	vma->vm_ops = &mmap_mem_ops;
+
 	/* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
 	if (remap_pfn_range(vma,
 			    vma->vm_start,
Index: linux/arch/x86_64/mm/pat.c
===================================================================
--- linux.orig/arch/x86_64/mm/pat.c
+++ linux/arch/x86_64/mm/pat.c
@@ -252,3 +252,39 @@ void free_mattr_vma(struct vm_area_struc
 		   pgprot_nonstd(vma->vm_page_prot));
 }
 
+/* /dev/mem interface. Use the previous mapping */
+pgprot_t
+phys_mem_access_prot(struct file *file, unsigned long pfn, unsigned long size,
+		     pgprot_t vma_prot)
+{
+	u64 offset = pfn << PAGE_SHIFT;
+	unsigned long flags;
+	unsigned long want_flags = 0;
+	if ((file->f_flags & O_SYNC) || (offset >= __pa(high_memory)))
+		want_flags = _PAGE_PCD;
+
+	/* When it's memory and not reserved force cached
+	   because we don't know about any other mappings */
+	if (pfn_valid(pfn) && !PageReserved(pfn_to_page(pfn)))
+		 want_flags = 0;
+
+	/* ignore error because we can't handle it here */
+	reserve_mattr(offset, offset+size, want_flags, &flags);
+	if (flags != want_flags) {
+		printk(KERN_INFO
+	"%s:%d /dev/mem expected mapping type %s for %Lx-%Lx, got %s\n",
+			current->comm, current->pid,
+			cattr_name(want_flags),
+			offset, offset+size,
+			cattr_name(flags));
+	}
+
+	return __pgprot((pgprot_val(vma_prot) & ~_PAGE_CACHE_MASK)|flags);
+}
+
+void unmap_devmem(unsigned long pfn, unsigned long size)
+{
+	u64 addr = (u64)pfn << PAGE_SHIFT;
+	free_mattr(addr, size, -1L);
+}
+
Index: linux/include/asm-x86_64/pgtable.h
===================================================================
--- linux.orig/include/asm-x86_64/pgtable.h
+++ linux/include/asm-x86_64/pgtable.h
@@ -474,4 +474,9 @@ extern int kern_addr_valid(unsigned long
 #define __HAVE_ARCH_PTE_SAME
 #include <asm-generic/pgtable.h>
 
+#define __HAVE_PHYS_MEM_ACCESS_PROT
+struct file;
+pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
+                              unsigned long size, pgprot_t vma_prot);
+
 #endif /* _X86_64_PGTABLE_H */
Index: linux/include/asm-i386/pgtable.h
===================================================================
--- linux.orig/include/asm-i386/pgtable.h
+++ linux/include/asm-i386/pgtable.h
@@ -529,4 +529,11 @@ do {									\
 
 #include <asm-generic/pgtable.h>
 
+#ifndef __ASSEMBLY__
+#define __HAVE_PHYS_MEM_ACCESS_PROT
+struct file;
+pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
+                              unsigned long size, pgprot_t vma_prot);
+#endif
+
 #endif /* _I386_PGTABLE_H */