From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alex =?utf-8?Q?Benn=C3=A9e?= <alex.bennee@linaro.org>
Subject: Re: [PATCH v4 03/12] KVM: arm64: guest debug, define API headers
Date: Fri, 15 May 2015 16:43:01 +0100
Message-ID: <871tihlud6.fsf@linaro.org>
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Cc: Mark Rutland <mark.rutland@arm.com>,
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To: Peter Maydell <peter.maydell@linaro.org>
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Peter Maydell <peter.maydell@linaro.org> writes:

> On 15 May 2015 at 16:14, Alex Benn=C3=A9e <alex.bennee@linaro.org> wr=
ote:
>>
>> Mark Rutland <mark.rutland@arm.com> writes:
>>
>>> On Fri, May 15, 2015 at 03:27:06PM +0100, Alex Benn=C3=A9e wrote:
>>>> +/*
>>>> + * See v8 ARM ARM D7.3: Debug Registers
>>>> + *
>>>> + * The control registers are architecturally defined as 32 bits b=
ut are
>>>> + * stored as 64 bit values alongside the value registers. This is=
 done
>>>
>>> Stale comment? They're stored as __u32 below.
>>
>> Gah yes it is.
>>
>>> It's possible that the registers could grow in future as happened i=
n the
>>> case of CLIDR_EL1, so it might be worth treating system registers
>>> generally as u64 values.
>>
>> Really? I mean the existing debug *control* registers have reserved =
bits
>> 24-31 so there is space for expansion.
>
> Other places in the userspace ABI which deal with sysregs (notably
> ONE_REG) consistently define them all as 64-bit (which makes sense
> anyway since the ISA only provides 64-bit accessors to them).
> "Architecturally 32 bits" only means "top 32 bits reserved".

=46air enough, I can switch it back. The main reason I had them as all =
64
bit before was because of the mapping onto the sys_regs context. If
everyone is happy bloating the ABI a little I'm OK with that. It will
make the hyp.S macro a little less ugly for one.

>
> -- PMM

--=20
Alex Benn=C3=A9e