From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <0e977e85c6ff64d54bac0b0301754f40@coraid.com>
From: erik quanstrom <quanstro@coraid.com>
Date: Wed, 22 Aug 2007 17:51:23 -0400
To: 9fans@cse.psu.edu
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Subject: [9fans] double-mapping KZERO in l.s
Topicbox-Message-UUID: b012251a-ead2-11e9-9d60-3106f5b1d025

perhaps this is completely obvious, but why are the first
4 mb double-mapped in l.s at virtual address 0 and KZERO?

also, am i mixed up or should the comment about the double
mapping be on the following line?

- erik

/*
 * Now ready to use the new map. Make sure the processor options are what is wanted.
 * It is necessary on some processors to immediately follow mode switching with a JMP instruction
 * to clear the prefetch queues.
 */
	MOVL	$PADDR(CPU0PDB), CX		/* load address of page directory */
	MOVL	(PDO(KZERO))(CX), DX		/* double-map KZERO at 0 */
	MOVL	DX, (PDO(0))(CX)
	MOVL	CX, CR3