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Re: [Qemu-devel] Subject: [PATCH] target-ppc: Add global timer group A t
From: |
David Gibson |
Subject: |
Re: [Qemu-devel] Subject: [PATCH] target-ppc: Add global timer group A to open-pic. |
Date: |
Wed, 26 Apr 2017 12:51:34 +1000 |
User-agent: |
Mutt/1.8.0 (2017-02-23) |
On Sun, Apr 23, 2017 at 07:37:55PM -0500, address@hidden wrote:
> David Gibson <address@hidden> wrote on 04/23/2017 06:17:22
> PM:
>
> > From: David Gibson <address@hidden>
> > To: Aaron Larson <address@hidden>
> > Cc: address@hidden, address@hidden, address@hidden
> > Date: 04/23/2017 06:54 PM
> > Subject: Re: Subject: [PATCH] target-ppc: Add global timer group A to
> open-pic.
> >
> > On Fri, Apr 21, 2017 at 02:58:23PM -0700, Aaron Larson wrote:
> > > Add global timer group A to open-pic. This patch is still somewhat
> > > dubious because I'm not sure how to determine what QEMU wants for the
> > > timer frequency. Suggestions solicited.
> >
> > This commit message really needs some more context. What's a "global
> > time group A" a and why do we want it?
>
> The open-pic spec includes two sets/groups of timers, groups A and B,
> 4 timers in each group. Previously in QEMU the timer group A
> registers were implemented but they did not "count" or generate any
> interrupts. The patch makes the timers to do both (count and generate
> interrupts).
Ok, sounds good, but this is exactly the sort of thing that needs to
go in the commit message.
> About a year ago I mentioned that we had implemented this and offered
> to submit a patch, which seemed to be acceptable. Sadly, when I
> reviewed the implementation it had several egregious errors that I
> didn't know how to fix until recently.
Ok. Now that you mention that, it rings a vague bell.
> Quite frankly I didn't expect the patch to be accepted in its current
> form for the reason mentioned in the above commit log and was hoping
> for some guidance. If this is no longer a desirable patch, I can
> certainly continue to maintain it locally for our use.
That's fine - but I need context of what the patch is attempting to
do, and why that's desirable in order to properly review it.
--
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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