Re: [PATCH] [RFC][V3] bluegene: use MMU feature flag to conditionalize L1 writethrough code

On Thu, Jun 9, 2011 at 6:42 PM, Benjamin Herrenschmidt
[off-list ref] wrote:

On Thu, 2011-06-09 at 09:58 -0500, Eric Van Hensbergen wrote:

quoted

On Tue, Jun 7, 2011 at 7:47 PM, Benjamin Herrenschmidt
[off-list ref] wrote:

quoted

BTW. Care to explain to me why you have U2 -both- in the arguments to
tlbwe and in MMUCR ? That doesn't look right to me... which one is used
where and when ?

My reading of the databook is that U2SWOAE is an enable bit that lets the U2
storage attribute control the behavior.

You mean the MMUCR variant ?

Yeah, the MMCR variant acts as an enable/mask for the U2 storage attribute.

Well, point is, parsing the device-tree from early boot asm is nasty,
unless you start extending the header but that sucks. That's why I'm
thinking it might be a good idea to look at what it takes to "convert"
the initial entry instead, even if that involves some cache flushing
(provided that's workable at all of course).

ah, okay.  I guess if its happening before the secondary cpus come up
then that should be workable.   I guess it doesn't hurt to try.

       -eric