From mboxrd@z Thu Jan  1 00:00:00 1970
From: eric.y.miao@gmail.com (Eric Miao)
Date: Wed, 21 Apr 2010 21:19:06 +0800
Subject: Simply disabling MMU in cpu_v7_reset doesn't work for kexec
In-Reply-To: <w2mf17812d71004210618vc68963cbn7ed50483a56140b7@mail.gmail.com>
References: <w2mf17812d71004210618vc68963cbn7ed50483a56140b7@mail.gmail.com>
Message-ID: <n2jf17812d71004210619qee8b8467u135fdbb44ff33049@mail.gmail.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Wed, Apr 21, 2010 at 9:18 PM, Eric Miao <eric.y.miao@gmail.com> wrote:
> Tried the following simple code to disable MMU in cpu_v7_reset() doesn't
> seem to work for kexec reboot. I was expecting the following instructions
> after MMU is disabled are still reachable in the instruction fetching pipe.
>

	.align	5
 ENTRY(cpu_v7_reset)
+	mrc	p15, 0, r1, c1, c0, 0		@ ctrl register
+	bic	r1, r1, #0x0001			@ ...............m
+	mcr	p15, 0, r1, c1, c0, 0		@ disable MMU
+	mcr	p15, 0, ip, c8, c7, 0		@ invalidate I and D TLBs
 	mov	pc, r0
 ENDPROC(cpu_v7_reset)


> Not tried JTAG but posted here early in case anyone knows the correct
> sequence of disabling MMU before reset.
>
> - eric
>