Make REBOOTADDR a physical address again.
 [jmk] --rw-rw-r-- M 785568 glenda sys 5203 Jan 18 17:13 sys/src/9/pc/mem.h
	/n/sourcesdump/2006/0118/plan9/sys/src/9/pc/mem.h:56,62 - 
	/n/sourcesdump/2006/0119/plan9/sys/src/9/pc/mem.h:56,62
	  #define	RMCODE		(KZERO+0x8000)		/* copy of first page of KTEXT */
	  #define	RMBUF		(KZERO+0x9000)		/* buffer for user space - known to vga */
	  #define	IDTADDR		(KZERO+0x10800)		/* idt */
	- #define	REBOOTADDR	(KZERO+0x11000)		/* reboot code - physical address */
	+ #define	REBOOTADDR	(0x11000)		/* reboot code - physical address */
	  #define	CPU0PDB		(KZERO+0x12000)		/* bootstrap processor PDB */
	  #define	CPU0PTE		(KZERO+0x13000)		/* bootstrap processor PTE's for 0-4MB */
	  #define	CPU0GDT		(KZERO+0x14000)		/* bootstrap processor GDT */
 [jmk] --rw-rw-r-- M 785568 glenda sys 3572 Jan 18 17:21 sys/src/9/pc/mkfile
	/n/sourcesdump/2006/0118/plan9/sys/src/9/pc/mkfile:118,124 - 
	/n/sourcesdump/2006/0119/plan9/sys/src/9/pc/mkfile:118,124
	  
	  reboot.h:	rebootcode.s
	  	$AS rebootcode.s
	- 	$LD -l -s -T0x1000 -R4 -o reboot.out rebootcode.$O
	+ 	$LD -l -s -T0x11000 -R4 -o reboot.out rebootcode.$O
	  	{echo 'uchar rebootcode[]={'
	  	 xd -1x reboot.out |
	  		sed -e '1,2d' -e 's/^[0-9a-f]+ //' -e 's/ ([0-9a-f][0-9a-f])/0x\1,/g'
 [jmk] --rw-rw-r-- M 785568 glenda sys 15153 Jan 18 17:14 sys/src/9/port/sysproc.c
	/n/sourcesdump/2006/0118/plan9/sys/src/9/port/sysproc.c:320,326 - 
	/n/sourcesdump/2006/0119/plan9/sys/src/9/port/sysproc.c:320,326
	  		if(((ulong)argp&(BY2PG-1)) < BY2WD)
	  			validaddr((ulong)argp, BY2WD, 0);
	  		validaddr((ulong)a, 1, 0);
	- 		nbytes += (vmemchr(a, 0, 0x7FFFFFFF) - a) + 1;
	+ 		nbytes += ((char*)vmemchr(a, 0, 0x7FFFFFFF) - a) + 1;
	  		nargs++;
	  	}
	  	ssize = BY2WD*(nargs+1) + ((nbytes+(BY2WD-1)) & ~(BY2WD-1));