Re: [PATCH 3/3] arm64: configs: Add virtconfig

From: Masahiro Yamada <masahiroy@kernel.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Mark Brown <broonie@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	 Will Deacon <will@kernel.org>,
	Nathan Chancellor <nathan@kernel.org>,
	 Nick Desaulniers <ndesaulniers@google.com>,
	Nicolas Schier <nicolas@fjasle.eu>,
	soc@kernel.org,  Mark Rutland <mark.rutland@arm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	 linux-arm-kernel@lists.infradead.org,
	linux-kbuild@vger.kernel.org,  linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] arm64: configs: Add virtconfig
Date: Tue, 14 Feb 2023 01:18:12 +0900	[thread overview]
Message-ID: <CAK7LNARfKgQgZ5Q6Djqs+K4WfhjG2wV=RWNY_mb=5Lz-1+USNQ@mail.gmail.com> (raw)
In-Reply-To: <467e7a7f-1703-4f13-8604-6d582e4f9b3e@app.fastmail.com>

On Tue, Feb 14, 2023 at 12:16 AM Arnd Bergmann <arnd@arndb.de> wrote:
>
> On Sat, Feb 11, 2023, at 08:37, Masahiro Yamada wrote:
> > On Sat, Feb 11, 2023 at 4:54 AM Mark Brown <broonie@kernel.org> wrote:
> >>
> >> Provide a slimline configuration intended to be booted on virtual
> >> machines, with the goal of providing a light configuration which will
> >> boot on and enable features available in mach-virt.  This is defined in
> >> terms of the standard defconfig, with an additional virt.config fragment
> >> which disables options unneeded in a virtual configuration.
> >>
> >> As a first step we just disable all the ARCH_ configuration options,
> >> disabling the build of all the SoC specific drivers.  This results in a
> >> kernel that builds about 25% faster in my testing, if this approach
> >> works for people we can add further options.
> >>
> >> Signed-off-by: Mark Brown <broonie@kernel.org>
> >> ---
> >>  arch/arm64/Makefile            |  6 ++++++
> >>  arch/arm64/configs/virt.config | 39 +++++++++++++++++++++++++++++++++++++++
> >>  2 files changed, 45 insertions(+)
>
> I like this a lot, I think that is very helpful and we can always build on
> top of it later with other fragments.
>
> We could still combine this with another Kconfig option that
> just hides all the real SoC options, which would turn this fragment
> into a one-line file and avoid having to update it whenever platforms
> get added.
>
> > Yeah, I have a _local_ script to apply
> > a similar config fragragment.
> >
> > When I run QEMU, I disable unneeded CONFIG_ARCH_*,
> > and also disable unneeded sub-systems.
> >
> > Not only me, many people are doing similar in their local env,
> > I guess.
> >
> >
> > Of course, I will not upstream my set of CONFIG options
> > since it is just my preference.
> > After all, this depends on people in my opinion.
>
> Do you have an opinion on the other two patches? If those
> look good to you, maybe I can just merge all three through the
> soc/defconfig branch for 6.3.
>
>       Arnd

scripts/Makefile.defconf is not what I'd maintain.
Please do whatever you want to do.

-- 
Best Regards
Masahiro Yamada