From: David Gibson <dwg@au1.ibm.com>
To: Hollis Blanchard <hollisb@us.ibm.com>
Cc: linuxppc-dev <linuxppc-dev@ozlabs.org>
Subject: Re: 44x bug: funny TLB writes?
Date: Fri, 21 Sep 2007 15:42:18 +1000 [thread overview]
Message-ID: <20070921054218.GA13470@localhost.localdomain> (raw)
In-Reply-To: <1190345652.25483.6.camel@basalt>
On Thu, Sep 20, 2007 at 10:34:12PM -0500, Hollis Blanchard wrote:
> I seem to have come across a strange bug while doing KVM development. It
> seems that the final tlbwe in finish_tlb (head_44x.S) is actually
> leaking RPN bits into the "attribute" word.
>
> When I set a breakpoint there and press enter on the serial console, I
> see r12=ef600703, which is the physical address of the UART on this chip
> (440EP), plus the correct permission bits at the bottom.
>
> Am I crazy? I'm not really looking to step through that assembly right
> now... Clearly (current) hardware is just ignoring these errant writes,
> but it should be fixed.
A quick glance at the code suggests this is indeed wrong. Hurrah.
Another reason to rewrite the 44x tlb miss handling.
PS. "errant" and "error" are not cognate, even if the chip doc
writers think so...
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
next prev parent reply other threads:[~2007-09-21 5:42 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-21 3:34 44x bug: funny TLB writes? Hollis Blanchard
2007-09-21 5:42 ` David Gibson [this message]
2007-09-21 6:38 ` Hollis Blanchard
2007-09-21 6:47 ` David Gibson
2007-09-21 17:37 ` Hollis Blanchard
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