From mboxrd@z Thu Jan  1 00:00:00 1970
From: erik quanstrom <quanstro@coraid.com>
Date: Thu, 12 Nov 2009 15:57:37 -0500
To: 9fans@9fans.net
Message-ID: <97f3a3e3c85b3c279d6121be7778ef43@coraid.com>
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Subject: [9fans] mmu fix?
Topicbox-Message-UUID: 9a3a2a5a-ead5-11e9-9d60-3106f5b1d025

perhaps i'm missing something, but we experienced
a crash in mmuwalk that was explained by interpreting
the garbage in a page allocated by mmuwalk as valid
page flags.  of course this did not end well.

/n/dump/2009/1112/sys/src/9/pc/mmu.c:624,629 - mmu.c:624,630
  				map = rampage();
  			if(map == nil)
  				panic("mmuwalk xspanalloc failed");
+ 			memset(map, 0, BY2PG);	/* d'oh! */
  			*table = PADDR(map)|PTEWRITE|PTEVALID;
  		}
  		table = KADDR(PPN(*table));

is there something that i'm missing here?  it's hard
to imagine that this doesn't cause problems more often.

- erik