linux-kernel - Re: [PATCH 04/17] x86/boot: Remove the 'bugger off' message

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Message-ID: <583bf766-5351-24b6-dbd6-fc5db6a7b2f8@zytor.com>
Date:   Sat, 19 Aug 2023 18:02:40 -0700
From:   "H. Peter Anvin" <hpa@...or.com>
To:     Ard Biesheuvel <ardb@...nel.org>, linux-efi@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Evgeniy Baskov <baskov@...ras.ru>,
        Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Jones <pjones@...hat.com>,
        Matthew Garrett <mjg59@...f.ucam.org>,
        Gerd Hoffmann <kraxel@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Marvin Häuser <mhaeuser@...teo.de>
Subject: Re: [PATCH 04/17] x86/boot: Remove the 'bugger off' message

On 8/18/23 06:44, Ard Biesheuvel wrote:
> Ancient (pre-2003) x86 kernels could boot from a floppy disk straight from
> the BIOS, using a small real mode boot stub at the start of the image
> where the BIOS would expect the boot record (or boot block) to appear.
> 
> Due to its limitations (kernel size < 1 MiB, no support for IDE, USB or
> El Torito floppy emulation), this support was dropped, and a Linux aware
> bootloader is now always required to boot the kernel from a legacy BIOS.
> 
> To smoothen this transition, the boot stub was not removed entirely, but
> replaced with one that just prints an error message telling the user to
> install a bootloader.
> 
> As it is unlikely that anyone doing direct floppy boot with such an
> ancient kernel is going to upgrade to v6.5+ and expect that this boot
> method still works, printing this message is kind of pointless, and so
> it should be possible to remove the logic that emits it.
> 
> Let's free up this space so it can be used to expand the PE header in a
> subsequent patch.
> 
> Signed-off-by: Ard Biesheuvel <ardb@...nel.org
>

Good riddance.

Acked-by: H. Peter Anvin (Intel) <hpa@...or.com>