[4/7] Xen VMM patch set : /dev/mem io_remap_page_range for CONFIG_XEN

[Ian Pratt <Ian.Pratt@cl.cam.ac.uk>]

This patch modifies /dev/mem to call io_remap_page_range rather than
remap_pfn_range under CONFIG_XEN.  This is required because in arch
xen we need to use a different function for mapping MMIO space vs
mapping psueudo-physical memory.  This allows the X server and other
programs that use /dev/mem for MMIO to work under Xen.

Signed-off-by: ian.pratt@cl.cam.ac.uk

---


diff -Nurp pristine-linux-2.6.10-rc2/drivers/char/mem.c tmp-linux-2.6.10-rc2-xen.patch/drivers/char/mem.c
--- pristine-linux-2.6.10-rc2/drivers/char/mem.c	2004-11-15 01:27:41.000000000 +0000
+++ tmp-linux-2.6.10-rc2-xen.patch/drivers/char/mem.c	2004-11-19 16:33:04.000000000 +0000
@@ -42,7 +42,12 @@ extern void tapechar_init(void);
  */
 static inline int uncached_access(struct file *file, unsigned long addr)
 {
-#if defined(__i386__)
+#ifdef CONFIG_XEN
+	if (file->f_flags & O_SYNC)
+		return 1;
+	/* Xen sets correct MTRR type on non-RAM for us. */
+	return 0;
+#elif defined(__i386__)
 	/*
 	 * On the PPro and successors, the MTRRs are used to set
 	 * memory types for physical addresses outside main memory,
@@ -201,6 +206,14 @@ static int mmap_mem(struct file * file, 
 		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 #endif
 
+#if defined(CONFIG_XEN)
+	if (io_remap_page_range(vma,
+				vma->vm_start,
+				vma->vm_pgoff << PAGE_SHIFT,
+				vma->vm_end-vma->vm_start,
+				vma->vm_page_prot))
+		return -EAGAIN;
+#else
 	/* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
 	if (remap_pfn_range(vma,
 			    vma->vm_start,
@@ -208,6 +221,7 @@ static int mmap_mem(struct file * file, 
 			    vma->vm_end-vma->vm_start,
 			    vma->vm_page_prot))
 		return -EAGAIN;
+#endif
 	return 0;
 }