2 files changed, 19 insertions, 0 deletions

diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 929d4fa73fd9..5dce3877eee5 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -80,6 +80,15 @@ config VT_HW_CONSOLE_BINDING
          information. For framebuffer console users, please refer to
          <file:Documentation/fb/fbcon.txt>.
 
+config DEVKMEM
+        bool "/dev/kmem virtual device support"
+        default y
+        help
+          Say Y here if you want to support the /dev/kmem device. The
+          /dev/kmem device is rarely used, but can be used for certain
+          kind of kernel debugging operations.
+          When in doubt, say "N".
+
 config SERIAL_NONSTANDARD
         bool "Non-standard serial port support"
         depends on HAS_IOMEM
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index e83623ead441..934ffafedaea 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -364,6 +364,7 @@ static int mmap_mem(struct file * file, struct vm_area_struct * vma)
         return 0;
 }
 
+#ifdef CONFIG_DEVKMEM
 static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
 {
         unsigned long pfn;
@@ -384,6 +385,7 @@ static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
         vma->vm_pgoff = pfn;
         return mmap_mem(file, vma);
 }
+#endif
 
 #ifdef CONFIG_CRASH_DUMP
 /*
@@ -422,6 +424,7 @@ static ssize_t read_oldmem(struct file *file, char __user *buf,
 extern long vread(char *buf, char *addr, unsigned long count);
 extern long vwrite(char *buf, char *addr, unsigned long count);
 
+#ifdef CONFIG_DEVKMEM
 /*
  * This function reads the *virtual* memory as seen by the kernel.
  */
@@ -626,6 +629,7 @@ static ssize_t write_kmem(struct file * file, const char __user * buf,
         *ppos = p;
         return virtr + wrote;
 }
+#endif
 
 #ifdef CONFIG_DEVPORT
 static ssize_t read_port(struct file * file, char __user * buf,
@@ -803,6 +807,7 @@ static const struct file_operations mem_fops = {
         .get_unmapped_area = get_unmapped_area_mem,
 };
 
+#ifdef CONFIG_DEVKMEM
 static const struct file_operations kmem_fops = {
         .llseek         = memory_lseek,
         .read           = read_kmem,
@@ -811,6 +816,7 @@ static const struct file_operations kmem_fops = {
         .open           = open_kmem,
         .get_unmapped_area = get_unmapped_area_mem,
 };
+#endif
 
 static const struct file_operations null_fops = {
         .llseek         = null_lseek,
@@ -889,11 +895,13 @@ static int memory_open(struct inode * inode, struct file * filp)
                         filp->f_mapping->backing_dev_info =
                                 &directly_mappable_cdev_bdi;
                         break;
+#ifdef CONFIG_DEVKMEM
                 case 2:
                         filp->f_op = &kmem_fops;
                         filp->f_mapping->backing_dev_info =
                                 &directly_mappable_cdev_bdi;
                         break;
+#endif
                 case 3:
                         filp->f_op = &null_fops;
                         break;
@@ -942,7 +950,9 @@ static const struct {
         const struct file_operations    *fops;
 } devlist[] = { /* list of minor devices */
         {1, "mem",     S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
+#ifdef CONFIG_DEVKMEM
         {2, "kmem",    S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
+#endif
         {3, "null",    S_IRUGO | S_IWUGO,           &null_fops},
 #ifdef CONFIG_DEVPORT
         {4, "port",    S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},