linux-kernel - Re: [PATCH RESEND] x86/boot: Add option to append to the cmdline

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Message-ID: <aN7hqiQg1cDIMIG9@goliath>
Date: Thu, 2 Oct 2025 20:33:46 +0000
From: "Daniel Walker (danielwa)" <danielwa@...co.com>
To: Brian Mak <makb@...iper.net>
CC: Dave Hansen <dave.hansen@...el.com>, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Dave Hansen
	<dave.hansen@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>, Andrew
 Morton <akpm@...ux-foundation.org>, "x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RESEND] x86/boot: Add option to append to the cmdline

On Thu, Oct 02, 2025 at 05:30:10PM +0000, Brian Mak wrote:
> On Oct 1, 2025, at 5:13 PM, Dave Hansen <dave.hansen@...el.com> wrote:
> 
> > On 10/1/25 16:04, Brian Mak wrote:
> >> To solve this limitation, we add CONFIG_CMDLINE_EXTEND, which is already
> >> available on several other architectures, to make the built-in command
> >> line append to the bootloader-provided command line.
> > 
> > I'd really rather not have another copy-and-paste of another
> > architecture's Kconfig bits into x86.
> > 
> > At the _very_ least, we'd get a boolean ARCH_HAS_CMDLIND_EXTEND which
> > would then expose an arch-independent CMDLINE_EXTEND option. Literally
> > duplicating Kconfig options just isn't scalable.
> 
> Hi Dave,
> 
> Thanks for your comments!
> 
> Sure, I'll introduce an arch-independent (ARCH_HAS_)CMDLINE_EXTEND option
> in v2.
> 
> > I also cringe every time I see code like this get added to arch/x86 that
> > really doesn't have anything to do with x86 and really only gets dumped
> > in to arch/ because there's never been a proper refactoring of all the
> > copy-and-pasted code.
> > 
> > In the end, refactoring Kconfig is dirt simple. Refactoring
> > builtin_cmdline[] into arch-independent code would be a lot harder.
> 
> In the past, there have been efforts to add arch-independent cmdline
> processing [1] (CC: Daniel Walker). These efforts have been stalled for a
> long time now though.


We use my change at Cisco in production, but I don't submit it often enough.

Daniel