linux-kernel - Re: [PATCH RFC bootconfig] Allow forcing unconditional bootconfig processing

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Message-ID: <20230224163307.GN2948950@paulmck-ThinkPad-P17-Gen-1>
Date:   Fri, 24 Feb 2023 08:33:07 -0800
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        corbet@....net, akpm@...ux-foundation.org, ndesaulniers@...gle.com,
        vbabka@...e.cz, hannes@...xchg.org, joel@...lfernandes.org,
        quic_neeraju@...cinc.com, urezki@...il.com
Subject: Re: [PATCH RFC bootconfig] Allow forcing unconditional bootconfig
 processing

On Sat, Feb 25, 2023 at 01:13:06AM +0900, Masami Hiramatsu wrote:
> Hi Geert,
> 
> On Fri, 24 Feb 2023 09:31:50 +0100
> Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> 
> > Hi Paul,
> > 
> > On Sat, Jan 7, 2023 at 5:33 PM Paul E. McKenney <paulmck@...nel.org> wrote:
> > > On Sun, Jan 08, 2023 at 12:22:15AM +0900, Masami Hiramatsu wrote:
> > > > BTW, maybe CONFIG_BOOT_CONFIG_EMBED is better to select this.
> > > > (or at least recommend to enable this)
> > >
> > > Like this?
> > >
> > >                                                         Thanx, Paul
> > >
> > > ------------------------------------------------------------------------
> > >
> > > commit d09a1505c51a70da38b34ac38062977299aef742
> > > Author: Paul E. McKenney <paulmck@...nel.org>
> > > Date:   Sat Jan 7 08:09:22 2023 -0800
> > >
> > >     bootconfig: Default BOOT_CONFIG_FORCE to y if BOOT_CONFIG_EMBED
> > >
> > >     When a kernel is built with CONFIG_BOOT_CONFIG_EMBED=y, the intention
> > >     will normally be to unconditionally provide the specified kernel-boot
> > >     arguments to the kernel, as opposed to requiring a separately provided
> > >     bootconfig parameter.  Therefore, make the BOOT_CONFIG_FORCE Kconfig
> > >     option default to y in kernels built with CONFIG_BOOT_CONFIG_EMBED=y.
> > >
> > >     The old semantics may be obtained by manually overriding this default.
> > >
> > >     Suggested-by: Masami Hiramatsu <mhiramat@...nel.org>
> > >     Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
> > >
> > > diff --git a/init/Kconfig b/init/Kconfig
> > > index 0fb19fa0edba9..97a0f14d9020d 100644
> > > --- a/init/Kconfig
> > > +++ b/init/Kconfig
> > > @@ -1379,6 +1379,7 @@ config BOOT_CONFIG
> > >  config BOOT_CONFIG_FORCE
> > >         bool "Force unconditional bootconfig processing"
> > >         depends on BOOT_CONFIG
> > > +       default y if BOOT_CONFIG_EMBED
> > >         help
> > >           With this Kconfig option set, BOOT_CONFIG processing is carried
> > >           out even when the "bootconfig" kernel-boot parameter is omitted.
> > 
> > Thanks for your patch, which is now commit 6ded8a28ed80e4cc
> > ("bootconfig: Default BOOT_CONFIG_FORCE to y if BOOT_CONFIG_EMBED").
> > 
> > After this change, an all{mod,yes}config kernel has:
> > 
> >     CONFIG_BOOT_CONFIG_FORCE=y
> >     CONFIG_BOOT_CONFIG_EMBED=y
> >     CONFIG_BOOT_CONFIG_EMBED_FILE=""
> > 
> > Will this actually work? I haven't tried booting such a kernel yet.
> 
> Yeah, good question. It is same as when you boot the kernel with 'bootconfig'
> but do not add the bootconfig file to initrd. You may see below message
> on boot log, but kernel boots normally. :)
> 
>  'bootconfig' found on command line, but no bootconfig found
> 
> (Maybe it is better to fix the message, because if BOOT_CONFIG_FORCE=y, this
> will be shown without 'bootconfig' on command line.)

I just tried it again, and for me it just silently ignores the bootconfig
setup.  Which is what I recall happening when I tried it when creating
the patch.

Here is the .config file pieces of interest:

CONFIG_BOOT_CONFIG=y
CONFIG_BOOT_CONFIG_FORCE=y
CONFIG_BOOT_CONFIG_EMBED=y
CONFIG_BOOT_CONFIG_EMBED_FILE=""

Anyone else seeing something different?

							Thanx, Paul

> Thank you!
> 
> > 
> > Gr{oetje,eeting}s,
> > 
> >                         Geert
> > 
> > -- 
> > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
> > 
> > In personal conversations with technical people, I call myself a hacker. But
> > when I'm talking to journalists I just say "programmer" or something like that.
> >                                 -- Linus Torvalds
> 
> 
> -- 
> Masami Hiramatsu (Google) <mhiramat@...nel.org>