From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
To: paulmck@kernel.org
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
corbet@lwn.net, akpm@linux-foundation.org,
ndesaulniers@google.com, vbabka@suse.cz, hannes@cmpxchg.org,
joel@joelfernandes.org, quic_neeraju@quicinc.com,
urezki@gmail.com
Subject: Re: [PATCH RFC bootconfig] Allow forcing unconditional bootconfig processing
Date: Sat, 25 Feb 2023 09:58:11 +0900 [thread overview]
Message-ID: <20230225095811.926a8ebaee4ca2d1fb9d9e45@kernel.org> (raw)
In-Reply-To: <20230224163307.GN2948950@paulmck-ThinkPad-P17-Gen-1>
On Fri, 24 Feb 2023 08:33:07 -0800
"Paul E. McKenney" <paulmck@kernel.org> wrote:
> 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?
Hmm, from the code, I think you'll see that message in early console log.
In init/main.c:
----
#ifdef CONFIG_BOOT_CONFIG
/* Is bootconfig on command line? */
static bool bootconfig_found = IS_ENABLED(CONFIG_BOOT_CONFIG_FORCE);
static size_t initargs_offs;
#else
----
And
----
static void __init setup_boot_config(void)
{
...
strscpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
err = parse_args("bootconfig", tmp_cmdline, NULL, 0, 0, 0, NULL,
bootconfig_params);
if (IS_ERR(err) || !bootconfig_found)
return;
/* parse_args() stops at the next param of '--' and returns an address */
if (err)
initargs_offs = err - tmp_cmdline;
if (!data) {
pr_err("'bootconfig' found on command line, but no bootconfig found\n");
return;
}
----
Thus, if CONFIG_BOOT_CONFIG_FORCE=y, the process passes the below check
if (IS_ERR(err) || !bootconfig_found)
return;
But since we have an empty 'data', the error should be printed.
Thank you,
>
> 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>
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
next prev parent reply other threads:[~2023-02-25 0:58 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-05 0:58 [PATCH RFC bootconfig] Allow forcing unconditional bootconfig processing Paul E. McKenney
2023-01-07 15:22 ` Masami Hiramatsu
2023-01-07 16:22 ` Paul E. McKenney
2023-01-08 6:04 ` Masami Hiramatsu
2023-01-09 4:25 ` Paul E. McKenney
2023-01-09 23:56 ` Masami Hiramatsu
2023-01-10 0:07 ` Paul E. McKenney
2023-01-10 0:54 ` Masami Hiramatsu
2023-01-10 1:09 ` Paul E. McKenney
2023-01-10 14:17 ` Masami Hiramatsu
2023-01-10 15:02 ` Paul E. McKenney
2023-01-26 19:26 ` Paul E. McKenney
2023-01-27 5:57 ` Masami Hiramatsu
2023-01-31 18:50 ` Paul E. McKenney
2023-02-24 8:31 ` Geert Uytterhoeven
2023-02-24 16:13 ` Masami Hiramatsu
2023-02-24 16:33 ` Paul E. McKenney
2023-02-25 0:58 ` Masami Hiramatsu [this message]
2023-02-25 1:19 ` Paul E. McKenney
2023-02-26 23:16 ` Masami Hiramatsu
2023-02-27 16:56 ` Paul E. McKenney
2023-02-27 23:29 ` Masami Hiramatsu
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