linux-kernel - Re: [tip: x86/build] x86/boot: Drop CRC-32 checksum and the build tool that generates it

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Message-ID: <2fddc2e9-8c97-48de-bcc3-29645d58f0f1@intel.com>
Date: Fri, 11 Apr 2025 12:52:50 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: linux-kernel@...r.kernel.org, linux-tip-commits@...r.kernel.org
Cc: Ard Biesheuvel <ardb@...nel.org>, Ingo Molnar <mingo@...nel.org>,
 "H. Peter Anvin" <hpa@...or.com>, Ian Campbell <ijc@...lion.org.uk>,
 Linus Torvalds <torvalds@...ux-foundation.org>, x86@...nel.org
Subject: Re: [tip: x86/build] x86/boot: Drop CRC-32 checksum and the build
 tool that generates it

On 4/11/25 12:33, Dave Hansen wrote:
...
> The only weird thing I'm doing is booting the kernel with qemu's -kernel
> argument.

I lied. I'm doing other weird things. I have a local script named
"truncate" that's not the same thing as /usr/bin/truncate. Guess what
this patch started doing:

>  quiet_cmd_image = BUILD   $@
> -silent_redirect_image = >/dev/null
> -cmd_image = $(obj)/tools/build $(obj)/setup.bin $(obj)/vmlinux.bin \
> -			       $(obj)/zoffset.h $@ $($(quiet)redirect_image)
> +      cmd_image = cp $< $@; truncate -s %4K $@; cat $(obj)/vmlinux.bin >>$@

				 ^ right there

I'm an idiot. That was a poorly named script and it cost me a kernel
bisect and poking at the patch for an hour. <sigh>

Sorry for the noise.