linux-kernel - Re: Smarter Kconfig help

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Message-ID: <20190306125022.ikqy66lf25yifxwc@shell.armlinux.org.uk>
Date:   Wed, 6 Mar 2019 12:50:22 +0000
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Mark Rutland <mark.rutland@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Lucas Stach <l.stach@...gutronix.de>,
        Peng Hao <peng.hao2@....com.cn>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: Smarter Kconfig help

Hi Mark,

On Wed, Mar 06, 2019 at 09:35:21AM +0000, Mark Rutland wrote:
> On Tue, Mar 05, 2019 at 05:31:12PM +0000, Russell King - ARM Linux admin wrote:
> > Guys,
> 
> Hi Russell,
> 
> > We need to be smarter when writing Kconfig help.  I'm just going
> > through updating my build trees with the results of 5.0 development,
> > and a number of the help texts are next to useless.  For example,
> > 
> > PVPANIC - is this something that should be enabled for a host or
> > guest kernel?  Answer: you have to read the driver code to find out.
> 
> When I looked at the help text:
> 
>     This driver provides support for the pvpanic device.  pvpanic is
>     a paravirtualized device provided by QEMU; it lets a virtual machine
>     (guest) communicate panic events to the host.
> 
> ... it seemed clear to me that this was for a guest, given the text says
> QEMU provides the device. I guess you read that as meaning QEMU asks the
> host kernel to provide the device to the guest?

Yes - that's exactly where the confusion was.  It could be something
like a tap network device to allow a guest access to a facility on the
host, or it could be something that the guest kernel uses to communicate
with its host environment.

> Do you have a suggestion for how to word that unambiguously?

It used to be normal to include a sugestion in the help text that
guided when an option should be enabled.  So, adding something like:

    "Say Y here if you are building a kernel for a virtual machine."

would make it clear.  This used to be standard throughout the kernel,
but it seems in recent years, this has been omitted.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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