Re: [PATCH RFC bootconfig] Allow forcing unconditional bootconfig processing

Paul E. McKenney
2023-02-24T16:33:11Z

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@linux-m68k.org> wrote:
>
> > Hi Paul,
> >
> > On Sat, Jan 7, 2023 at 5:33 PM Paul E. McKenney <paulmck@kernel.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@kernel.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@kernel.org>
> > > Signed-off-by: Paul E. McKenney <paulmck@kernel.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@linux-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@kernel.org>