Re: [Qemu-devel] [Qemu-ppc] [PATCH 6/8] target-ppc: Rework get_physical_address()

[David Gibson]

On Sat, Feb 23, 2013 at 11:38:23AM +0100, Alexander Graf wrote:
> 
> 
> Am 23.02.2013 um 07:28 schrieb David Gibson <address@hidden>:
> 
> > On Fri, Feb 22, 2013 at 05:06:52PM +0100, Alexander Graf wrote:
> >> 
> >> On 12.02.2013, at 03:00, David Gibson wrote:
> >> 
> >>> Currently get_physical_address() first checks to see if translation is
> >>> enabled in the MSR, then in the translation on case switches on the mmu
> >>> type.  Except that for BookE MMUs, translation is always on, and so it
> >>> has to switch in the "translation off" case as well and do the same thing
> >>> as the translation on path for those MMUs.  Plus, even translation off
> >>> doesn't behave exactly the same on the various MMU types so there are
> >>> further mmu type checks in the "translation off" path.
> >>> 
> >>> As a first step to cleaning this up, this patch moves the switch on mmu
> >>> type to the top level, then makes the translation on/off check just for
> >>> those mmu types where it is meaningful.
> >> 
> >> Eventually the mmu translation should just be a class dispatched
> >> indirect function call. I don't think it's within the scope of this
> >> first round of cleanup though.
> > 
> > I agree.  My plan was to first push the switching all up to the top
> > level as I've done, then replace that with a method dispatch
> > afterwards.
> 
> If you're convinced the path you're taking is already correct, don't
> post patches as RFC :).

Well, I'm not sure about all of it.

More to the point, I'm really not sure what you're suggesting I do
differently.  We can't switch to a method invocation when there are
mmu type dependencies scattered all through the path.  So that change
more or less has to go after what I have already.

-- 
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

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