linux-kernel - Re: [PATCH v3 1/7] arm64: add support for the AMU extension v1

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Message-ID: <20200212182708.GA25105@arm.com>
Date:   Wed, 12 Feb 2020 18:27:08 +0000
From:   Ionela Voinescu <ionela.voinescu@....com>
To:     Vladimir Murzin <vladimir.murzin@....com>
Cc:     Suzuki Kuruppassery Poulose <suzuki.poulose@....com>,
        mark.rutland@....com, maz@...nel.org, linux-doc@...r.kernel.org,
        peterz@...radead.org, catalin.marinas@....com,
        linux-pm@...r.kernel.org, rjw@...ysocki.net,
        linux-kernel@...r.kernel.org, mingo@...hat.com,
        viresh.kumar@...aro.org, linux-arm-kernel@...ts.infradead.org,
        sudeep.holla@....com, will@...nel.org, valentin.schneider@....com,
        lukasz.luba@....com
Subject: Re: [PATCH v3 1/7] arm64: add support for the AMU extension v1

On Wednesday 12 Feb 2020 at 16:24:42 (+0000), Vladimir Murzin wrote:
> Hi,
> 
> On 2/12/20 4:10 PM, Ionela Voinescu wrote:
> > Hi Suzuki,
> > 
> > On Wednesday 12 Feb 2020 at 11:30:44 (+0000), Suzuki Kuruppassery Poulose wrote:
> >>> +static int __init set_disable_amu(char *str)
> >>> +{
> >>> +	int value = 0;
> >>> +
> >>> +	disable_amu = get_option(&str, &value) ? !!value : true;
> >> minor nit: You could simply use strtobool(str) here, which accepts:
> >>
> >> disable_amu= [0/1/on/off/y/n]
> >>
> > Yes, this was intentional as I wanted "disable_amu" to be a valid option
> > as well, not only "disable_amu=<option>".
> > 
> > If you don't mind I'd like to keep it like this. Currently the use of
> > AMU is enabled by default, and the most common kernel parameter to
> > disable it would be "disable_amu". Allowing "disable_amu=0" is just in
> > case we change the default in the kernel to not support AMU and we'd
> > like platforms to be able to enable it. 
> > 
> 
> Sorry for jumping into thread, but can we avoid negatives into naming which
> accept values? If is always tricky to get expected effect when both are combined.
> 
> If value doesn't really mater than can it be just "noamu"?
> 
> If value does matter can it be (per Suzuki) amu=[0/1/on/off/y/n]?
> 
> Or can you postpone introduction of "just in case" option till that case happens?
>

No worries, thank you very much for the input. I'll change it to
amu=[0/1/on/off/y/n] for clarity.

Thank you,
Ionela.

> Cheers
> Vladimir