[src/trunk]: src/share/man/man4/man4.i386 Some polishing, thanks to Klaus Kle...

[hubertf <hubertf%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/6bc4f36b2566
branches:  trunk
changeset: 512028:6bc4f36b2566
user:      hubertf <hubertf%NetBSD.org@localhost>
date:      Tue Jul 03 16:37:18 2001 +0000

description:
Some polishing, thanks to Klaus Klein for feedback!

diffstat:

 share/man/man4/man4.i386/io.4 |  41 +++++++++++++++++++++--------------------
 1 files changed, 21 insertions(+), 20 deletions(-)

diffs (57 lines):

diff -r 2a0f2d0837da -r 6bc4f36b2566 share/man/man4/man4.i386/io.4
--- a/share/man/man4/man4.i386/io.4     Tue Jul 03 14:40:41 2001 +0000
+++ b/share/man/man4/man4.i386/io.4     Tue Jul 03 16:37:18 2001 +0000
@@ -34,32 +34,33 @@
 .Nm io
 .Nd I/O privilege file
 .Sh DESCRIPTION
-.Pp 
-.Bd -offset center
-.Em This device is deprecated, please use
-.Em Xr i386_iopl 2
-.Em instead!
-.Ed 
-.Pp 
-The special file
+.Bf -symbolic
+This device is obsolete and is provided for compatibility purposes
+only; use
+.Xr i386_iopl 2
+instead.
+.Ef
+.Pp
+After opening
 .Pa /dev/io
-is a controlled security hole that allows a process to gain I/O
-privileges
-.Pq which are normally reserved for kernel-internal code ,
-and for supporting inb/outb in userspace.
-Any process that holds a file descriptor on
-.Pa /dev/io
-open will get its
-.Em IOPL
-bits in the flag register set, thus allowing it to perform direct
-I/O operations.  This can be useful in order to write userland
+for writing
+the process is granted full I/O privileges; closing the returned file
+descriptor does
+.Em not
+result in revocation of these privileges.
+The new I/O privileges can be useful in order to write userland
 programs that handle some hardware directly.
 .Pp
 The entire access control is handled by the file access permissions
 of
 .Pa /dev/io ,
-so care should be taken in granting rights for this device.  Note
-that even read/only access will grant the full I/O privileges.
+so care should be taken in granting rights for this device.
+.Pp
+I/O privilege on access to 
+.Pa /dev/io
+is only granted if the kernel was built with the
+.Dv COMPAT_10
+option. 
 .Sh FILES
 .Bl -tag -width Pa -compact
 .It Pa /dev/io