patch-1.3.2 linux/include/asm-i386/shmparam.h

• Lines: 45
• Date: Fri Jun 16 21:11:21 1995
• Orig file: v1.3.1/linux/include/asm-i386/shmparam.h
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.1/linux/include/asm-i386/shmparam.h linux/include/asm-i386/shmparam.h
@@ -0,0 +1,44 @@
+#ifndef _ASMI386_SHMPARAM_H
+#define _ASMI386_SHMPARAM_H
+
+/* address range for shared memory attaches if no address passed to shmat() */
+#define SHM_RANGE_START	0x50000000
+#define SHM_RANGE_END	0x60000000
+
+/*
+ * Format of a swap-entry for shared memory pages currently out in
+ * swap space (see also mm/swap.c).
+ *
+ * SWP_TYPE = SHM_SWP_TYPE
+ * SWP_OFFSET is used as follows:
+ *
+ *  bits 0..6 : id of shared memory segment page belongs to (SHM_ID)
+ *  bits 7..21: index of page within shared memory segment (SHM_IDX)
+ *		(actually fewer bits get used since SHMMAX is so low)
+ */
+
+/*
+ * Keep _SHM_ID_BITS as low as possible since SHMMNI depends on it and
+ * there is a static array of size SHMMNI.
+ */
+#define _SHM_ID_BITS	7
+#define SHM_ID_MASK	((1<<_SHM_ID_BITS)-1)
+
+#define SHM_IDX_SHIFT	(_SHM_ID_BITS)
+#define _SHM_IDX_BITS	15
+#define SHM_IDX_MASK	((1<<_SHM_IDX_BITS)-1)
+
+/*
+ * _SHM_ID_BITS + _SHM_IDX_BITS must be <= 24 on the i386 and
+ * SHMMAX <= (PAGE_SIZE << _SHM_IDX_BITS).
+ */
+
+#define SHMMAX 0x3fa000			/* max shared seg size (bytes) */
+#define SHMMIN 1 /* really PAGE_SIZE */	/* min shared seg size (bytes) */
+#define SHMMNI (1<<_SHM_ID_BITS)	/* max num of segs system wide */
+#define SHMALL				/* max shm system wide (pages) */ \
+	(1<<(_SHM_IDX_BITS+_SHM_ID_BITS))
+#define	SHMLBA PAGE_SIZE		/* attach addr a multiple of this */
+#define SHMSEG SHMMNI			/* max shared segs per process */
+
+#endif /* _ASMI386_SHMPARAM_H */