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From: slash.tmp@free•fr (Mason)
To: linux-arm-kernel@lists•infradead.org
Subject: Reading twd_base at run-time
Date: Wed, 01 Apr 2015 14:07:05 +0200	[thread overview]
Message-ID: <551BDF69.4020205@free.fr> (raw)
In-Reply-To: <20150327205301.GD4019@n2100.arm.linux.org.uk>

On 27/03/2015 21:53, Russell King - ARM Linux wrote:

> That's one scenario.  Here's the scenario Mark is describing - one which
> has real-world examples:
>
> Hardware engineer picks address A for rev A and sets CP15 to address A.
> Everything works.  Hardware engineer then picks address B for rev B, but
> forgets to update CP15.  It breaks.

The hardware engineer told me that whatever arbitrary value is chosen
for PERIPH_BASE is automatically exported through CP15 (which is how
I thought this worked). So there is no "forgetting to update CP15"
(for this platform, at least).

> If it's in DT, it can be fixed.  It should be there anyway as part of
> the hardware description.  DT is a description of the hardware.

I thought DT was supposed to describe hardware that /cannot/ be probed
or discovered at run-time?

If everything could be probed at run-time, what would be the point of DT?

(For my own reference, DT on x86)
http://thread.gmane.org/gmane.linux.kernel/1104014
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/log/arch/x86/kernel/devicetree.c

Regards.

  reply	other threads:[~2015-04-01 12:07 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-27 16:16 Reading twd_base at run-time Mason
2015-03-27 16:35 ` Marc Zyngier
2015-03-27 20:33   ` Mason
2015-03-27 20:53     ` Russell King - ARM Linux
2015-04-01 12:07       ` Mason [this message]
2015-04-01 12:12         ` Russell King - ARM Linux
2015-04-01 12:47           ` Mason
2015-04-01 12:28         ` Marc Zyngier
2015-04-01 12:47           ` Mason
2015-04-01 13:01           ` Mason
2015-04-01 13:14             ` Marc Zyngier
2015-04-01 14:39               ` Mason
2015-04-01 14:56                 ` Marc Zyngier

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