Re: [PATCH v2 02/17] powerpc/cell: Move data segment faulting code out of cell platform

Michael Neuling
2014-10-02T00:42:55Z

On Wed, 2014-10-01 at 16:47 +1000, Michael Ellerman wrote:
> On Tue, 2014-30-09 at 10:34:51 UTC, Michael Neuling wrote:
> > From: Ian Munsie <imunsie@au1.ibm.com>
> >
> > __spu_trap_data_seg() currently contains code to determine the VSID and ESID
> > required for a particular EA and mm struct.
> >
> > This code is generically useful for other co-processors. This moves the code
> > of the cell platform so it can be used by other powerpc code. It also adds 1TB
> > segment handling which Cell didn't have.
>
> I'm not loving this.
>
> For starters the name "copro_data_segment()" doesn't contain any verbs, and it
> doesn't tell me what it does.

Ok.

> If we give it a name that says what it does, we get copro_get_ea_esid_and_vsid().
> Or something equally ugly.

Ok

> And then in patch 10 you move the bulk of the logic into calculate_vsid().

That was intentional on my part. I want this patch to be clear that
we're moving this code out of cell. Then I wanted the optimisations to
be in a separate patch. It does mean we touch the code twice in this
series, but I was hoping it would make it easier to review. Alas. :-)

> So instead can we:
> - add a small helper that does the esid calculation, eg. calculate_esid() ?
> - factor out the vsid logic into a helper, calculate_vsid() ?
> - rework the spu code to use those, dropping __spu_trap_data_seg()
> - use the helpers in the cxl code

OK, I think I can do that. I might change the name to something better
in this patch, but I'll leave these cleanups to the later patch 10.

Mikey