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Re: [Qemu-devel] [PATCH] target-ppc: Eliminate redundant and incorrect f
From: |
David Gibson |
Subject: |
Re: [Qemu-devel] [PATCH] target-ppc: Eliminate redundant and incorrect function booke206_page_size_to_tlb |
Date: |
Tue, 28 Jun 2016 13:16:10 +1000 |
User-agent: |
Mutt/1.6.1 (2016-04-27) |
On Mon, Jun 27, 2016 at 10:55:03AM -0500, address@hidden wrote:
> David Gibson <address@hidden> wrote on 06/27/2016 12:32:13
> AM:
>
> > From: David Gibson <address@hidden>
> > To: address@hidden
> > Cc: address@hidden, address@hidden, address@hidden
> > Date: 06/27/2016 12:30 AM
> > Subject: Re: [PATCH] target-ppc: Eliminate redundant and incorrect
> function booke206_page_size_to_tlb
> >
> > On Sun, Jun 26, 2016 at 09:38:03PM -0500, address@hidden wrote:
> > > David Gibson <address@hidden> wrote on 06/26/2016
> 08:36:52
> > > PM:
> > >
> > > > From: David Gibson <address@hidden>
> > > > To: Aaron Larson <address@hidden>
> > > > Cc: address@hidden, address@hidden, address@hidden
> > > > Date: 06/26/2016 08:58 PM
> > > > Subject: Re: [PATCH] target-ppc: Eliminate redundant and incorrect
> > > function booke206_page_size_to_tlb
> > > >
> > > > On Fri, Jun 24, 2016 at 12:11:00PM -0700, Aaron Larson wrote:
> > > > >
> > > > > Eliminate redundant and incorrect booke206_page_size_to_tlb
> function
> > > > > from ppce500_spin.c in preference to previously existing but newly
> > > > > exported definition from e500.c
> > > > >
> > > > > Signed-off-by: Aaron Larson <address@hidden>
> > > >
> > > > Uh.. sorry.. can you provide a reference explaining why the removed
> > > > version is wrong? Doesn't this depend on which MMU Architecture
> > > > Version we're emulating?
> > >
> > > Sure, the code is internally inconsistent (shift assumed didn't match
> > > shift defined). I will provide an update commit message, similar to
> the
> > > original posting I made a few days ago with the "direction"
> > > corrected.
> >
> > Right, I can see that the two old versions were different, which was
> > clearly wrong. What I'm looking for is an explanation of why the one
> > you've picked is the right one, not the other one.
>
> How's this?
>
> Eliminate redundant and incorrect booke206_page_size_to_tlb function
> from ppce500_spin.c in preference to previously existing but newly
> exported definition from e500.c
>
> The booke206_page_size_to_tlb function in e500.c was updated in commit
> 2bd9543cd303d9f6cbd37b7466bb03543035156b to reflect a change in the
> definition of MAS1_TSIZE_SHIFT from 8 (corresponding to a min TLB page
> size of 4kb) to a value of 7 (TLB page size 2k). The
> booke206_page_size_to_tlb() function defined in ppce500_spin.c was
> never updated to reflect the change in MAS1_TSIZE_SHIFT.
Ah, yes, that looks good. Except that the convention when citing
other commits is to just use the first 7 characters of the commit id,
but to include the 1 line description. So:
...commit 2bd9543 "ppc: booke206: use MAV=2.0 TSIZE definition, fix
4G pages" to reflect...
> In http://lists.nongnu.org/archive/html/qemu-ppc/2016-06/msg00533.html,
> Scott Wood suggested this "root cause" explanation:
>
> SW> The patch that changed MAS1_TSIZE_SHIFT from 8 to 7 was around the
> SW> same time as the patch that added this code, which is probably why
> SW> adjusting it got missed. Commit 2bd9543cd3 did update the
> SW> equivalent code in ppce500_mpc8544ds.c, which now resides in
> SW> hw/ppc/e500.c and has been changed to not assume a power-of-2
> SW> size. The ppce500_spin version should be eliminated.
>
--
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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