From bfbb9ce67005673c7b7c8b2267024adef44f7d1d Mon Sep 17 00:00:00 2001
From: Poul-Henning Kamp <phk@FreeBSD.org>
Date: Tue, 11 May 1999 19:55:07 +0000
Subject: Divorce "dev_t" from the "major|minor" bitmap, which is now called
 udev_t in the kernel but still called dev_t in userland.

Provide functions to manipulate both types:
        major()         umajor()
        minor()         uminor()
        makedev()       umakedev()
        dev2udev()      udev2dev()

For now they're functions, they will become in-line functions
after one of the next two steps in this process.

Return major/minor/makedev to macro-hood for userland.

Register a name in cdevsw[] for the "filedescriptor" driver.

In the kernel the udev_t appears in places where we have the
major/minor number combination, (ie: a potential device: we
may not have the driver nor the device), like in inodes, vattr,
cdevsw registration and so on, whereas the dev_t appears where
we carry around a reference to a actual device.

In the future the cdevsw and the aliased-from vnode will be hung
directly from the dev_t, along with up to two softc pointers for
the device driver and a few houskeeping bits.  This will essentially
replace the current "alias" check code (same buck, bigger bang).

A little stunt has been provided to try to catch places where the
wrong type is being used (dev_t vs udev_t), if you see something
not working, #undef DEVT_FASCIST in kern/kern_conf.c and see if
it makes a difference.  If it does, please try to track it down
(many hands make light work) or at least try to reproduce it
as simply as possible, and describe how to do that.

Without DEVT_FASCIST I belive this patch is a no-op.

Stylistic/posixoid comments about the userland view of the <sys/*.h>
files welcome now, from userland they now contain the end result.

Next planned step: make all dev_t's refer to the same devsw[] which
means convert BLK's to CHR's at the perimeter of the vnodes and
other places where they enter the game (bootdev, mknod, sysctl).
---
 sys/kern/kern_conf.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 73 insertions(+), 2 deletions(-)

(limited to 'sys/kern/kern_conf.c')

diff --git a/sys/kern/kern_conf.c b/sys/kern/kern_conf.c
index c20e2aa87214..e6aa7389ca9a 100644
--- a/sys/kern/kern_conf.c
+++ b/sys/kern/kern_conf.c
@@ -30,7 +30,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * $Id: kern_conf.c,v 1.35 1999/05/09 08:18:12 phk Exp $
+ * $Id: kern_conf.c,v 1.36 1999/05/09 13:00:46 phk Exp $
  */
 
 #include <sys/param.h>
@@ -70,7 +70,15 @@ cdevsw_add(dev_t *descrip,
 		struct cdevsw *newentry,
 		struct cdevsw **oldentry)
 {
-	int i ;
+	int i;
+	static int setup;
+
+	if (!setup) {
+		for (i = 0; i < NUMCDEV; i++)
+			if (!bmaj2cmaj[i])
+				bmaj2cmaj[i] = 254;
+		setup++;
+	}
 
 	if ( *descrip == NODEV) {	/* auto (0 is valid) */
 		/*
@@ -161,3 +169,66 @@ devsw_module_handler(module_t mod, int what, void* arg)
 	else
 		return 0;
 }
+
+/*
+ * dev_t and u_dev_t primitives
+ */
+
+#define DEVT_FASCIST 1
+
+int 
+major(dev_t x)
+{
+#ifdef DEVT_FASCIST
+	return(253 - ((x >> 8) & 0xff));
+#else
+	return((x >> 8) & 0xff);
+#endif
+}
+
+int
+minor(dev_t x)
+{
+	return(x & 0xffff00ff);
+}
+
+dev_t
+makedev(int x, int y)
+{
+#ifdef DEVT_FASCIST
+        return (((253 - x) << 8) | y);
+#else
+        return ((x << 8) | y);
+#endif
+}
+
+udev_t
+dev2udev(dev_t x)
+{
+	return umakedev(major(x), minor(x));
+}
+
+dev_t
+udev2dev(udev_t x, int b)
+{
+	return makedev(umajor(x), uminor(x));
+}
+
+int
+uminor(udev_t dev)
+{
+	return(dev & 0xffff00ff);
+}
+
+int
+umajor(udev_t dev)
+{
+	return((dev & 0xff00) >> 8);
+}
+
+udev_t
+umakedev(int x, int y)
+{
+        return ((x << 8) | y);
+}
+
-- 
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