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From: Wei Huang <wei@redhat.com>
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Date: Tue, 2 Feb 2016 09:16:21 -0600
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Subject: Re: [Qemu-devel] [PATCH 2/2] ARM: PL061: Misc cleaning fields for
 PL061 device state
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To: Michael Tokarev <mjt@tls.msk.ru>, Peter Maydell <peter.maydell@linaro.org>
Cc: QEMU Trivial <qemu-trivial@nongnu.org>, Igor Mammedov <imammedo@redhat.com>, Shannon Zhao <shannon.zhao@linaro.org>, QEMU Developers <qemu-devel@nongnu.org>, Shannon Zhao <zhaoshenglong@huawei.com>



On 02/02/2016 01:03 AM, Michael Tokarev wrote:
> 01.02.2016 21:01, Peter Maydell wrote:
>> On 1 February 2016 at 17:20, Wei Huang <wei@redhat.com> wrote:
>>> This patch removes float_high field of PL061State, which doesn't seem
>>> to be used anywhere.
> []
>>> @@ -88,7 +87,6 @@ static const VMStateDescription vmstate_pl061 = {
>>>          VMSTATE_UINT32(slr, PL061State),
>>>          VMSTATE_UINT32(den, PL061State),
>>>          VMSTATE_UINT32(cr, PL061State),
>>> -        VMSTATE_UINT32(float_high, PL061State),
>>>          VMSTATE_UINT32_V(amsel, PL061State, 2),
>>>          VMSTATE_END_OF_LIST()
>>
>> This would be a migration compatibility break, so at a minimum
>> you need to bump the vmstate struct versions.
> 
> Is it worth the effort to remove this field if it causes
> compatibility break?  Maybe keep it around, it doesn't hurt?

It doesn't hurt. So either way is fine. I just happened to find it while
reviewing the code.

> At the very least, we may rename it to "unused_float_high",
> or something, to indicate it is a known-unused?

I don't think renaming solves any problem. Either we keep this variable
as it is or remove it.

> 
> Thanks,
> 
> /mjt
>