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Date:   Fri, 4 Aug 2023 10:36:17 -0700
From:   "Paul E. McKenney" <paulmck@kernel.org>
To:     Alexey Dobriyan <adobriyan@gmail.com>
Cc:     akpm@linux-foundation.org, mhiramat@kernel.org, arnd@kernel.org,
        ndesaulniers@google.com, sfr@canb.auug.org.au,
        linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
        kernel-team@meta.com
Subject: Re: [PATCH RFC bootconfig] 1/2] fs/proc: Add /proc/cmdline_load for
 boot loader arguments
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On Fri, Aug 04, 2023 at 08:23:20PM +0300, Alexey Dobriyan wrote:
> On Thu, Jul 27, 2023 at 08:37:00PM -0700, Paul E. McKenney wrote:
> > In kernels built with CONFIG_BOOT_CONFIG_FORCE=y, /proc/cmdline will
> > show all kernel boot parameters, both those supplied by the boot loader
> > and those embedded in the kernel image.  This works well for those who
> > just want to see all of the kernel boot parameters, but is not helpful to
> > those who need to see only those parameters supplied by the boot loader.
> > This is especially important when these parameters are presented to the
> > boot loader by automation that might gather them from diverse sources.
> > 
> > Therefore, provide a /proc/cmdline_load file that shows only those kernel
> > boot parameters supplied by the boot loader.
> 
> > +static int cmdline_load_proc_show(struct seq_file *m, void *v)
> > +{
> > +	seq_puts(m, boot_command_line);
> > +	seq_putc(m, '\n');
> > +	return 0;
> > +}
> > +
> >  static int __init proc_cmdline_init(void)
> >  {
> >  	struct proc_dir_entry *pde;
> > @@ -19,6 +27,11 @@ static int __init proc_cmdline_init(void)
> >  	pde = proc_create_single("cmdline", 0, NULL, cmdline_proc_show);
> >  	pde_make_permanent(pde);
> >  	pde->size = saved_command_line_len + 1;
> > +	if (IS_ENABLED(CONFIG_BOOT_CONFIG_FORCE)) {
> > +		pde = proc_create_single("cmdline_load", 0, NULL, cmdline_load_proc_show);
> > +		pde_make_permanent(pde);
> > +		pde->size = strnlen(boot_command_line, COMMAND_LINE_SIZE) + 1;
> > +	}
> 
> Please add it as separate fs/proc/cmdline_load.c file so that name of
> the file matches name of the /proc file.

Thank you, will do!

> The name "cmdline_load" is kind of non-descriptive. Mentioning "bootloader"
> somewhere should improve things.

If we can all quickly come to agreement on a name, I can of course easily
change it.

/proc/cmdline_bootloader?  Better than /proc/cmdline_from_bootloader,
I suppose.  /proc/cmdline_bootldr?  /proc/bootloader by analogy with
/proc/bootconfig?  Something else?

							Thanx, Paul