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From: erik quanstrom <quanstro@quanstro.net>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] double-mapping KZERO in l.s
Date: Wed, 22 Aug 2007 21:54:55 -0400	[thread overview]
Message-ID: <6459fc9293ea05fe92e4594382a4d30b@quanstro.net> (raw)
In-Reply-To: <13426df10708221842v42de932dnd94b70868dcbf470@mail.gmail.com>

> But the EIP has to access the instructions. After the mov, you're
> still at low memory. Paging is turned on at this time. The  JMP is
> running at 0x10000something. So you turn paging on and do a jump, but
> paging is on when you do the jmp and fetch from low memory. To make
> the ifetch work you have to have the low map on.
> 
> I'll look at that code tonight again to make sure I'm not imaging
> things, but I think this is right.
> 
> ron

that sounds logical to me, i was thinking that this would work because
the processor had already fetched the next instruction.  but, duh,
	mov x, crn
is a serializing instruction.  (amd arch reference, vol 3, p. 280.)

thanks.

- erik


      reply	other threads:[~2007-08-23  1:54 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-08-22 21:51 erik quanstrom
2007-08-22 23:02 ` ron minnich
2007-08-22 23:44   ` erik quanstrom
2007-08-23  1:42     ` ron minnich
2007-08-23  1:54       ` erik quanstrom [this message]

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