Add padding space and a version number to the md_ioctl structre for future

extension.

Add ability to create a preload disk giving an address and a length
(suggested by imp)

Fix bug relating to very small md(4) devices.

Update md.c copyright to reflect the status of code copied from vn.c.
(noticed by dillon)

3 files changed, 25 insertions, 5 deletions

diff --git a/sbin/mdconfig/mdconfig.8 b/sbin/mdconfig/mdconfig.8
index 824bacc..c7ccba9 100644
--- a/sbin/mdconfig/mdconfig.8
+++ b/sbin/mdconfig/mdconfig.8
@@ -52,6 +52,7 @@
 .Fl a
 .Fl t Ar type 
 .Op Fl o Ar [no]option
+.Op Fl b Ar baseaddress
 .Op Fl s Ar size
 .Op Fl f Ar file
 .Op Fl u Ar unit
@@ -80,8 +81,8 @@ Storage for this type of memory disk is allocated with
 .Xr malloc 9 .
 This limits the size to the malloc bucket limit in the kernel.
 .It Ar preload
-This type represents memory disks which were instantiated by objects loaded
-by the bootloader.  They can not be created on the fly.
+This type represents memory disks which are backed by memory outside the kernels normal address space.
+These can be instantiated automatically by objects loaded by the bootloader or configured on the fly.
 .It Ar vnode
 A file specified with 
 .Fl f Ar file
@@ -89,6 +90,8 @@ becomes the backingstore for this memory disk.
 .It Ar swap
 swapspace is used to back this memory disk.
 .El
+.It Fl b Ar baseaddress
+Starting address in kernel virtual space of the memory to be used for a ``preload'' type disk.
 .It Fl f Ar file
 Filename to use for the vnode type memory disk.
 .It Fl s Ar size
@@ -108,7 +111,13 @@ Automatically allocate the next free unit number for this disk.
 The basename of the disk is printed on stdout.
 .It Ar [no]compress
 Enable/Disable compression features to reduce memory usage.
+.It Ar [no]readonly
+Enable/Disable readonly mode.
 .El
+.It Fl u Ar unit
+Force the
+.Xr md(4)
+device to use a specific unit number.
 .El
 .Sh EXAMPLES
 .Pp
@@ -138,6 +147,12 @@ To create and mount a 128MByte swap backed filesystem on
 .Dl newfs -f 4096 /dev/md10c
 .Dl tunefs -n enable /dev/md10c
 .Dl mount /dev/md10c /tmp
+.Pp
+It is practically impossible to give a universal example of the ``preload'' type of disk,
+it is mainly useful in the embedded systems market, but to give a feel for how it works:
+On most standard PC architecture machines this will create a disk backed by the BIOS ROM:
+.Pp
+.Dl mdconfig -a -t preload -s 128k -b 0xc00fe000
 .Sh SEE ALSO
 .Xr md 4 ,
 .Xr disklabel 8 ,
diff --git a/sbin/mdconfig/mdconfig.c b/sbin/mdconfig/mdconfig.c
index dca1b40..9f43877 100644
--- a/sbin/mdconfig/mdconfig.c
+++ b/sbin/mdconfig/mdconfig.c
@@ -44,7 +44,7 @@ main(int argc, char **argv)
 	int cmdline = 0;
 
 	for (;;) {
-		ch = getopt(argc, argv, "adf:o:s:t:u:");
+		ch = getopt(argc, argv, "ab:df:o:s:t:u:");
 		if (ch == -1)
 			break;
 		switch (ch) {
diff --git a/sys/sys/mdioctl.h b/sys/sys/mdioctl.h
index 6782e1a..1507e6f 100644
--- a/sys/sys/mdioctl.h
+++ b/sys/sys/mdioctl.h
@@ -54,13 +54,18 @@ enum md_types {MD_MALLOC, MD_PRELOAD, MD_VNODE, MD_SWAP};
  */
 
 struct md_ioctl {
+	unsigned	md_version;	/* Structure layout version */
 	unsigned	md_unit;	/* unit number */
 	enum md_types	md_type ;	/* type of disk */
-	char		md_file[MAXPATHLEN + 1]; /* pathname of file to mount */
-	unsigned	md_size;	/* (returned) size of disk */
+	char		*md_file;	/* pathname of file to mount */
+	unsigned	md_size;	/* size of disk in DEV_BSIZE units */
 	unsigned	md_options;	/* options */
+	u_int64_t	md_base;	/* base address */
+	int		pad[100];	/* padding for future ideas */
 };
 
+#define MDIOVERSION	1
+
 /*
  * Before you can use a unit, it must be configured with MDIOCSET.
  * The configuration persists across opens and closes of the device;