[PATCH - for playing only] change type of dev_t

[PATCH - for playing only] change type of dev_t

[Andries.Brouwer]

Below some random patch, not to be applied, so that
people can play with a 32-bit dev_t.

Nothing here is hewn in stone.
By some coincidence the division below is 16+16, but
a simple edit turns that into 12+20 or 32+32.
Elsewhere there are no (well, there still are a few,
but they will be eliminated), there are no assumptions
on the sizes involved.

A major and a minor are unsigned ints of unknown size.

Of course not all filesystems can handle all sizes.

Andries

[I still see a B_FREE here - had removed that earlier,
but perhaps the patch was not applied. There is another
occurrence in video/pm3fb.h that can be removed, and one
in video/pm3fb.c that should become NODEV. Will find this
patch again.]

----------------------- 19-devt-type -----------------------
diff -u --recursive --new-file -X /linux/dontdiff a/fs/libfs.c b/fs/libfs.c
--- a/fs/libfs.c	Thu Jan  2 14:32:11 2003
+++ b/fs/libfs.c	Tue Mar 18 22:14:48 2003
@@ -340,6 +340,6 @@
 const char * kdevname(kdev_t dev)
 {
 	static char buffer[32];
-	sprintf(buffer, "%02x:%02x", major(dev), minor(dev));
+	sprintf(buffer, "%04x:%04x", major(dev), minor(dev));
 	return buffer;
 }
diff -u --recursive --new-file -X /linux/dontdiff a/include/asm-i386/posix_types.h b/include/asm-i386/posix_types.h
--- a/include/asm-i386/posix_types.h	Mon Feb 24 23:02:56 2003
+++ b/include/asm-i386/posix_types.h	Tue Mar 18 22:14:48 2003
@@ -7,7 +7,7 @@
  * assume GCC is being used.
  */
 
-typedef unsigned short	__kernel_dev_t;
+typedef unsigned long	__kernel_dev_t;
 typedef unsigned long	__kernel_ino_t;
 typedef unsigned short	__kernel_mode_t;
 typedef unsigned short	__kernel_nlink_t;
diff -u --recursive --new-file -X /linux/dontdiff a/include/linux/kdev_t.h b/include/linux/kdev_t.h
--- a/include/linux/kdev_t.h	Fri Nov 22 22:40:57 2002
+++ b/include/linux/kdev_t.h	Tue Mar 18 22:14:48 2003
@@ -70,13 +70,13 @@
  * static arrays, and they are sized for a 8-bit index.
  */
 typedef struct {
-	unsigned short value;
+	unsigned int value;
 } kdev_t;
 
-#define KDEV_MINOR_BITS		8
-#define KDEV_MAJOR_BITS		8
+#define KDEV_MINOR_BITS		16
+#define KDEV_MAJOR_BITS		16
 
-#define __mkdev(major,minor)	(((major) << KDEV_MINOR_BITS) + (minor))
+#define __mkdev(major, minor)	(((major) << KDEV_MINOR_BITS) + (minor))
 
 #define mk_kdev(major, minor)	((kdev_t) { __mkdev(major,minor) } )
 
@@ -99,7 +99,6 @@
 
 #define HASHDEV(dev)	(kdev_val(dev))
 #define NODEV		(mk_kdev(0,0))
-#define B_FREE		(mk_kdev(0xff,0xff))
 
 extern const char * kdevname(kdev_t);	/* note: returns pointer to static data! */
 
@@ -110,17 +109,55 @@
 
 #define kdev_none(d1)	(!kdev_val(d1))
 
-/* Mask off the high bits for now.. */
-#define minor(dev)	((dev).value & 0xff)
-#define major(dev)	(((dev).value >> KDEV_MINOR_BITS) & 0xff)
+#define minor(dev)	((dev).value & 0xffff)
+#define major(dev)	(((dev).value >> KDEV_MINOR_BITS) & 0xffff)
 
 /* These are for user-level "dev_t" */
+/* Since glibc uses 8+8 in <include/sysmacros.h>, we'll get
+   incompatibilities with a simple scheme like 12+20.
+   Use 8+8 for 16-bit values, some other division, say 16+16,
+   for 32-bit values. */
 #define MINORBITS	8
 #define MINORMASK	((1U << MINORBITS) - 1)
 
-#define MAJOR(dev)	((unsigned int) ((dev) >> MINORBITS))
-#define MINOR(dev)	((unsigned int) ((dev) & MINORMASK))
-#define MKDEV(ma,mi)	(((ma) << MINORBITS) | (mi))
+#include <linux/types.h>	/* dev_t */
+#if 1
+/* macro versions */
+
+#define MAJOR(dev)	((unsigned int)(((dev) & 0xffff0000) ? ((dev) >> 16) & 0xffff : ((dev) >> 8) & 0xff))
+#define MINOR(dev)	((unsigned int)(((dev) & 0xffff0000) ? ((dev) & 0xffff) : ((dev) & 0xff)))
+#define MKDEV(ma,mi)	((dev_t)((((ma) & ~0xff) == 0 && ((mi) & ~0xff) == 0) ? (((ma) << 8) | (mi)) : (((ma) << 16) | (mi))))
+
+#else
+/* inline function versions */
+
+static inline unsigned int
+MAJOR(dev_t dev) {
+	unsigned int ma;
+
+	ma = ((dev >> 16) & 0xffff);
+	if (ma == 0)
+		ma = ((dev >> 8) & 0xff);
+	return ma;
+}
+
+static inline unsigned int
+MINOR(dev_t dev) {
+	unsigned int mi;
+
+	mi = (dev & 0xffff);
+	if (mi == dev)
+		mi = (dev & 0xff);
+	return mi;
+}
+
+static inline dev_t
+MKDEV(unsigned int ma, unsigned int mi) {
+	if ((ma & ~0xff) == 0 && (mi & ~0xff) == 0)
+		return ((ma << 8) | mi);
+	return ((ma << 16) | mi);
+}
+#endif
 
 /*
  * Conversion functions
@@ -128,12 +165,16 @@
 
 static inline int kdev_t_to_nr(kdev_t dev)
 {
-	return MKDEV(major(dev), minor(dev));
+	unsigned int ma = major(dev);
+	unsigned int mi = minor(dev);
+	return MKDEV(ma, mi);
 }
 
-static inline kdev_t to_kdev_t(int dev)
+static inline kdev_t to_kdev_t(dev_t dev)
 {
-	return mk_kdev(MAJOR(dev),MINOR(dev));
+	unsigned int ma = MAJOR(dev);
+	unsigned int mi = MINOR(dev);
+	return mk_kdev(ma, mi);
 }
 
 #else /* __KERNEL__ */

Re: [PATCH - for playing only] change type of dev_t

[Andy Pfiffer]

On Tue, 2003-03-18 at 14:13, Andries.Brouwer@cwi.nl wrote:
> Below some random patch, not to be applied, so that
> people can play with a 32-bit dev_t.

I have dumped this set of patches into OSDL's patch system.  The builds
are still pending, but it should be possible in awhile to run tests with
this patch stack in the automated test environment at OSDL.

The patch stack:

1st patch:
http://www.osdl.org/cgi-bin/plm?module=patch_info&patch_id=1706

2nd patch:
http://www.osdl.org/cgi-bin/plm?module=patch_info&patch_id=1707

3rd patch:
http://www.osdl.org/cgi-bin/plm?module=patch_info&patch_id=1708

4th patch to flip the switch:
http://www.osdl.org/cgi-bin/plm?module=patch_info&patch_id=1709

Regards,
Andy

Re: [PATCH - for playing only] change type of dev_t

[Andrey Klochko]

Andries.Brouwer@cwi.nl wrote:

>  * assume GCC is being used.
>  */
> 
>-typedef unsigned short	__kernel_dev_t;
>+typedef unsigned long	__kernel_dev_t;
>
Shouldn't this be
typedef unsigned int __kernel_dev_t;
according to

>@@ -70,13 +70,13 @@
>  * static arrays, and they are sized for a 8-bit index.
>  */
> typedef struct {
>-	unsigned short value;
>+	unsigned int value;
> } kdev_t;
> 
>
Andrey

-- 
-------------------------------------------------------------
Andrey Klochko
System Administrator
Sibley School of Mechanical and Aerospace Engineering
288 Grumman Hall
Cornell University
Ithaca, NY 14853