Re: [Qemu-devel] [Qemu-ppc] [0/8] RFC: target-ppc: Start disentangling different MMU types

[David Gibson]

On Sat, Feb 23, 2013 at 11:35:08AM +0100, Alexander Graf wrote:
> 
> 
> Am 23.02.2013 um 09:28 schrieb David Gibson <address@hidden>:
> 
> > On Fri, Feb 22, 2013 at 05:15:22PM +0100, Alexander Graf wrote:
> >> 
> >> On 12.02.2013, at 03:00, David Gibson wrote:
> >> 
> >>> The target-ppc code supports CPUs with a number of different MMU
> >>> types: there's both the 32-bit and 64-bit versions of the "classic"
> >>> hash page table based powerpc mmu and there's also the BookE and 40x
> >>> MMUs.
> >>> 
> >>> Currently handling of all these has a roughly shared path in
> >>> mmu_helper.c.  Although code sharing is usually a good idea, in this
> >>> case the MMUs really aren't similar enough for this to be useful.
> >>> Instead it results in checking and behaving differently at many, many
> >>> different points in the path leading to an unreadable tangle of code.
> >>> 
> >>> This patch series is a first step to cleaning this up, moving to a
> >>> model where we have a single switch on the MMU family at the top-level
> >>> entry points, then have a simpler, clearer separate code path for each
> >>> MMU type.  More specifically, it disentangles the path for the 64-bit
> >>> classic hash MMU into its own new file.  The other MMU types keep the
> >>> existing code (minus 64-bit hash specific conditionals) for now.
> >>> Disentangling those as well would be a good idea, but would be best
> >>> done by someone with more resources to test those other platforms than
> >>> I have.
> >>> 
> >>> For now, the resulting 64-bit hash path retains the same structure as
> >>> the original shared code, just the obvious conditionals on other mmu
> >>> types are removed.  This path is fairly ugly in itself, but cleaning
> >>> that up is a later step, now much simpler without the other MMU types
> >>> to deal with at the same time.
> >> 
> >> Looks like a nice and long overdue cleanup. A few points I'd like to see 
> >> addressed:
> >> 
> >>  - Instead of exporting common helper functions, put them into a
> >>  new mmu-hash.h as static inline. That way things can get optimized
> >>  a lot better.
> > 
> > The common helpers are all gone again by the end of the series, so is
> > there really any point?
> 
> Oh, really? I must have missed the bit where you remove / unexport
> them then ;).

11/32 "Disentangle hash mmu helper functions"

-- 
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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