Re: [Qemu-ppc] Subject: [PATCH] target-ppc: Add global timer group A to open-pic.

[alarson]

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).

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.

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.\

Aaron.