linux-kernel - Re: [PATCH v3] Decompressors: Add boot-time XZ support

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Message-Id: <201012110023.16771.lasse.collin@tukaani.org>
Date:	Sat, 11 Dec 2010 00:23:16 +0200
From:	Lasse Collin <lasse.collin@...aani.org>
To:	pavel@...linux.ru
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] Decompressors: Add boot-time XZ support

On 2010-12-10 Pavel Vasilyev wrote:
> On 10.12.2010 21:50, Lasse Collin wrote:
> > From: Lasse Collin <lasse.collin@...aani.org>
> 
> [--- ням ---]
> 
> > +config KERNEL_XZ
> > +	bool "XZ"
> > +	depends on HAVE_KERNEL_XZ
> > +	help
> > +	  XZ uses the LZMA2 algorithm and instruction set specific
> > +	  BCJ filters which can improve compression ratio of executable
> > +	  code. The size of the kernel is about 30% smaller with XZ in
> > +	  comparison to gzip. On architectures for which there is a BCJ
> > +	  filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
> > +	  will create a few percent smaller kernel than plain LZMA.
> > +
> > +	  The speed is about the same as with LZMA: The decompression
> > +	  speed of XZ is better than that of bzip2 but worse than gzip
> > +	  and LZO. Compression is slow.
> > +
> > 
> >  config KERNEL_LZO
> >  
> >  	bool "LZO"
> >  	depends on HAVE_KERNEL_LZO
> 
> Not worked without this:
> 
> --- кусь ---
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index e330da2..d27a9c7 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -52,6 +52,7 @@ config X86
>         select HAVE_KERNEL_BZIP2
>         select HAVE_KERNEL_LZMA
>         select HAVE_KERNEL_LZO
> +       select HAVE_KERNEL_XZ
>         select HAVE_HW_BREAKPOINT
>         select HAVE_MIXED_BREAKPOINTS_REGS
>         select PERF_EVENTS
> 
> --- кусь ---
> 
> .... and for other archs needed.

Support for XZ-compressed kernel on x86 is in a separate patch:

    http://lkml.org/lkml/2010/12/2/236

I hope other people will do similar patches for other archs later.

-- 
Lasse Collin  |  IRC: Larhzu @ IRCnet & Freenode
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