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added /dev/mordor

--- a/sys/man/3/arch

+++ b/sys/man/3/arch

@@ -12,6 +12,7 @@

 .B /dev/iol

 .B /dev/iow

 .B /dev/irqalloc

+.B /dev/mordor

 .SH DESCRIPTION

 This device presents textual information about PC hardware and allows

 user-level control of the I/O ports on x86-class and DEC Alpha machines.

@@ -121,6 +122,10 @@

 I/O ports.

 The port accessed is determined by the byte offset of the

 file descriptor.

+.PP

+Reads and writes to

+.IR mordor

+will inevitably cause the front to fall off.

 .SH EXAMPLE

 The following code reads from an x86 byte I/O port.

 .IP

--- a/sys/src/9/pc/devarch.c

+++ b/sys/src/9/pc/devarch.c

@@ -987,6 +987,20 @@

 	return n;

 }

+static long

+mordorread(Chan*, void*, long, vlong)

+{

+	error("one does not simply read from mordor");

+	return 0;

+}

+

+static long

+mordorwrite(Chan*, void*, long, vlong)

+{

+	error("one does not simply write into mordor");

+	return 0;

+}

+

 void

 archinit(void)

 {

@@ -1035,6 +1049,7 @@

 	addarchfile("cputype", 0444, cputyperead, nil);

 	addarchfile("archctl", 0664, archctlread, archctlwrite);

+	addarchfile("mordor", 0666, mordorread, mordorwrite);

 }

 /*

-- 

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