7882 Add /dev/full , the always-full memory device
Reviewed by: Adam Stevko <adam.stevko@gmail.com>
Reviewed by: Toomas Soome <tsoome@me.com>

@@ -23,10 +23,11 @@
  * Use is subject to license terms.
  */
 
 /*
  * Copyright (c) 2015, Joyent, Inc.  All rights reserved.
+ * Copyright (c) 2017 James S Blachly, MD <james.blachly@gmail.com>
  */
 
 #ifndef _SYS_MEM_H
 #define _SYS_MEM_H
 

@@ -43,10 +44,11 @@
 #define M_MEM           0       /* /dev/mem - physical main memory */
 #define M_KMEM          1       /* /dev/kmem - virtual kernel memory */
 #define M_NULL          2       /* /dev/null - EOF & Rathole */
 #define M_ALLKMEM       3       /* /dev/allkmem - virtual kernel memory & I/O */
 #define M_ZERO          12      /* /dev/zero - source of private memory */
+#define M_FULL          13      /* /dev/full - write always ret ENOSPC */
 
 /*
  * Private ioctl for libkvm: translate virtual address to physical address.
  */
 #define MEM_VTOP                (('M' << 8) | 0x01)