linux-kernel - Re: [PATCH] m68k: Add target for lz4 compressed vmlinux

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Message-ID: <5dd0a031-dd7b-4078-b1a8-6b760248390b@t-8ch.de>
Date: Sat, 9 Aug 2025 09:50:31 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Daniel Palmer <daniel@...f.com>
Cc: geert@...ux-m68k.org, linux-m68k@...ts.linux-m68k.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] m68k: Add target for lz4 compressed vmlinux

On 2025-08-09 10:55:29+0900, Daniel Palmer wrote:
> Traditionally gzip (/bzip?) has been the compressed image format
> but its a pain to decompress because its very hard to load and
> decompress it in chunks which you need to do if you don't
> have enough memory to load the whole kernel image and decompress
> it somewhere else.
> 
> With lz4 you can set a block size, read it from the header,
> and then you only need memory for a single block and the
> decompressed kernel.
> 
> I use lz4 compressed images on 68000 with 8MB of ram
> and MVME147 with 16MB. I want to use lz4 in my fork of EMILE
> to boot m68k macs because streaming decompress of gzip is painful.
> 
> Signed-off-by: Daniel Palmer <daniel@...f.com>
> ---
>  arch/m68k/Makefile | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/arch/m68k/Makefile b/arch/m68k/Makefile
> index 0abcf994ce55..a56e853037c0 100644
> --- a/arch/m68k/Makefile
> +++ b/arch/m68k/Makefile
> @@ -124,6 +124,17 @@ else
>  	$(KBZIP2) -1c vmlinux >vmlinux.bz2
>  endif
>  
> +vmlinux.lz4: vmlinux
> +
> +ifndef CONFIG_KGDB
> +	cp vmlinux vmlinux.tmp
> +	$(STRIP) vmlinux.tmp
> +	$(LZ4) -z9f vmlinux.tmp vmlinux.lz4
> +	rm vmlinux.tmp
> +else
> +	$(LZ4) -z9f vmlinux vmlinux.lz4
> +endif

Splitting the vmlinux.tmp creation into a dedicated target would make
all the compressor targets simpler. It will need a bit more disk space,
but there are a bunch of vmlinux copies already in any case.

> +
>  CLEAN_FILES += vmlinux.gz vmlinux.bz2

CLEAN_FILES also needs to be updated.

>  archheaders:
> -- 
> 2.50.0
>