Re: [PATCH v13 01/20] ARM64: Move PMU register related defines to asm/perf_event.h

From: Shannon Zhao <zhaoshenglong@huawei.com>
To: Marc Zyngier <marc.zyngier@arm.com>, Will Deacon <will.deacon@arm.com>
Cc: <kvmarm@lists.cs.columbia.edu>, <christoffer.dall@linaro.org>,
	<linux-arm-kernel@lists.infradead.org>, <kvm@vger.kernel.org>,
	<wei@redhat.com>, <cov@codeaurora.org>, <shannon.zhao@linaro.org>,
	<peter.huangpeng@huawei.com>, <hangaohuai@huawei.com>
Subject: Re: [PATCH v13 01/20] ARM64: Move PMU register related defines to asm/perf_event.h
Date: Tue, 1 Mar 2016 02:50:13 +0800	[thread overview]
Message-ID: <56D492E5.4040709@huawei.com> (raw)
In-Reply-To: <56D4428B.5000505@arm.com>


On 2016/2/29 21:07, Marc Zyngier wrote:
> Shannon,
> 
> On 25/02/16 02:02, Shannon Zhao wrote:
>>
>>
>> On 2016/2/25 1:52, Will Deacon wrote:
>>> On Wed, Feb 24, 2016 at 01:08:21PM +0800, Shannon Zhao wrote:
>>>> From: Shannon Zhao <shannon.zhao@linaro.org>
>>>>
>>>> To use the ARMv8 PMU related register defines from the KVM code, we move
>>>> the relevant definitions to asm/perf_event.h header file and rename them
>>>> with prefix ARMV8_PMU_.
>>>>
>>>> Signed-off-by: Anup Patel <anup.patel@linaro.org>
>>>> Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
>>>> Acked-by: Marc Zyngier <marc.zyngier@arm.com>
>>>> Reviewed-by: Andrew Jones <drjones@redhat.com>
>>>> ---
>>>>  arch/arm64/include/asm/perf_event.h | 35 +++++++++++++++++++
>>>>  arch/arm64/kernel/perf_event.c      | 68 ++++++++++---------------------------
>>>>  2 files changed, 52 insertions(+), 51 deletions(-)
>>>
>>> Looks fine to me, but we're going to get some truly horrible conflicts
>>> in -next.
>>>
>>> I'm open to suggestions on the best way to handle this, but one way
>>> would be:
>>>
>>>   1. Duplicate all the #defines privately in KVM (queue via kvm tree)
>> This way seems not proper I think.
>>
>>>   2. Rebase this patch onto my perf/updates branch [1] (queue via me)
>> While to this series, it really relies on the perf_event.h to compile
>> and test, so maybe for KVM-ARM and KVM maintainers it's not proper.
>>
>>>   3. Patch at -rc1 dropping the #defines from (1) and moving to the new
>>>      perf_event.h stuff
>>>
>> I vote for this way. Since the patch in [1] is small and nothing else
>> relies on them, I think it would be simple to rebase them onto this series.
>>
>>> Thoughts?
>>>
>> Anyway, there are only 3 lines which have conflicts. I'm not sure
>> whether we could handle this when we merge them.
> 
> I think you're missing the point:
> 
> - We want both the arm64 perf and KVM trees to be easy to merge
> - The conflicts are not that simple to resolve
> - We want these conflicts to be solved before it hits Linus' tree
> 
Ah, sorry. I realized this later.

> With that in mind, here's what I'm suggesting we merge as a first patch:
> 
> https://git.kernel.org/cgit/linux/kernel/git/kvmarm/kvmarm.git/commit/?h=queue&id=2029b4b02691ec6ebba3d281068e783353d7e108
> 
> Once this and the perf/updates branch are merged, we can add one last
> patch reverting this hack and actually doing the renaming work (Will has
> posted a resolution for most of the new things).
> 
> Thoughts?
> 
It's fine I think. (It's first time to me to face this kind of problem.
:)). Thanks for your help.

-- 
Shannon