From: Sylvain Munaut <tnt@246tNt•com>
To: Chris Dumoulin <cdumoulin@ics-ltd•com>, linuxppc-embedded@ozlabs•org
Subject: Re: Calculating virtual address from physical address
Date: Fri, 05 May 2006 21:27:50 +0200 [thread overview]
Message-ID: <445BA736.30208@246tNt.com> (raw)
In-Reply-To: <445B6A80.2090202@ics-ltd.com>
Chris Dumoulin wrote:
> I'm using a Virtex II Pro-based board with a PPC405. The board is
> hanging somewhere very early in the kernel boot process. I believe it
> may be dying at the point where the MMU is enabled. In order to
> determine the exact point at which my board hangs, I'm blinking two LEDs
> in the assembly code found in arch/ppc/kernel/head_4xx.S, . Currently I
> am only able to successfully access the LEDs before the MMU is turned
> on, but I can't be sure that I'm calculating the virtual address
> properly when I try to access the LED after the MMU is turned on.
Typical when trying to bring up board ...
Once the MMU is turned on, you leds register are most likely ... nowhere
... i.e.
if you don't create a mapping your self there is just no virtual address
that will
access your leds physical address.
What I did on some ppc work was tu use a quick BAT mapping to map some leds.
It's pretty easy to setup. Be aware though that this mapping will get
wiped out when
the kernel sets up the BAT for itself.
Sylvain
next prev parent reply other threads:[~2006-05-05 19:28 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-05 15:08 Calculating virtual address from physical address Chris Dumoulin
2006-05-05 19:27 ` Sylvain Munaut [this message]
2006-05-05 20:24 ` Matt Porter
2006-05-05 20:58 ` Josh Boyer
2006-05-05 23:35 ` David H. Lynch Jr.
-- strict thread matches above, loose matches on Subject: below --
2006-05-06 8:43 Alexander Szekely
2006-05-06 18:43 Chris Dumoulin
2006-05-06 19:38 ` Grant Likely
2006-05-10 11:04 ` David H. Lynch Jr.
2006-05-10 16:43 ` Eugene Surovegin
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