patch-1.3.94 linux/include/asm-m68k/shm.h

• Lines: 25
• Date: Wed Dec 27 22:47:22 1995
• Orig file: v1.3.93/linux/include/asm-m68k/shm.h
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.93/linux/include/asm-m68k/shm.h linux/include/asm-m68k/shm.h
@@ -0,0 +1,24 @@
+#ifndef _M68K_SHM_H
+#define _M68K_SHM_H
+
+/* format of page table entries that correspond to shared memory pages
+   currently out in swap space (see also mm/swap.c):
+   bits 0-1 (PAGE_PRESENT) is  = 0
+   bits 8..2 (SWP_TYPE) are = SHM_SWP_TYPE
+   bits 31..9 are used like this:
+   bits 15..9 (SHM_ID) the id of the shared memory segment
+   bits 30..16 (SHM_IDX) the index of the page within the shared memory segment
+                    (actually only bits 25..16 get used since SHMMAX is so low)
+   bit 31 (SHM_READ_ONLY) flag whether the page belongs to a read-only attach
+*/
+/* on the m68k both bits 0 and 1 must be zero */
+
+#define SHM_ID_SHIFT	9
+#define _SHM_ID_BITS	7
+#define SHM_ID_MASK	((1<<_SHM_ID_BITS)-1)
+
+#define SHM_IDX_SHIFT	(SHM_ID_SHIFT+_SHM_ID_BITS)
+#define _SHM_IDX_BITS	15
+#define SHM_IDX_MASK	((1<<_SHM_IDX_BITS)-1)
+
+#endif /* _M68K_SHM_H */