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From: Scott Wood <oss@buserror.net>
To: Giuseppe Lippolis <giu.lippolis@gmail.com>, linuxppc-dev@lists.ozlabs.org
Date: Fri, 24 Mar 2017 17:10:05 -0500
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Subject: Re: AW: problem with cuImage.mpc834x_mds image
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On Fri, 2017-03-24 at 22:27 +0100, Giuseppe Lippolis wrote:
> > 
> Therefore the code crash during the call in:
>         bl      setup_common_caches
> 
> 
> I'm using the iomega_150d based on the MPC8347.
> 
> Do you have some tips about the setup_common_caches?

Once caching is enabled[1] you won't be able to do I/O until the MMU is set up
for an uncached I/O mapping.

-Scott

[1] Or at some similar point during early init.  It's been a while since I
worked on chips like this, so I don't recall the details of which caches are
enabled on kernel entry and whether there's some magic to exempt I/O, but I do
remember there being a stretch of time during init where doing I/O was a
problem.