linux-kernel - Re: Uncompressed kernel doesn't build on x86

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Message-ID: <20131114183842.2c4b10aa@IRBT4585>
Date:	Thu, 14 Nov 2013 18:38:42 -0500
From:	Pavel Roskin <proski@....org>
To:	Austin S Hemmelgarn <ahferroin7@...il.com>
Cc:	Christian Ruppert <christian.ruppert@...lis.com>,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Vineet Gupta <Vineet.Gupta1@...opsys.com>,
	Noam Camus <noamc@...hip.com>
Subject: Re: Uncompressed kernel doesn't build on x86_64

On Thu, 14 Nov 2013 09:13:44 -0500
Austin S Hemmelgarn <ahferroin7@...il.com> wrote:

> On 2013-11-14 03:32, Christian Ruppert wrote:
> > 2. A patch to enable uncompressed x86 kernels. As stated above, I
> > don't think this makes a lot of sense in itself but it might serve
> > as an example for people working on other platforms with
> > self-extracting kernels and the nozip not-decompression algorithm
> > might be useful on those platforms as well. I only had a single
> > x86-64 machine available to test this, however, so some more
> > testing might be required.
> 
> I disagree with the argument that an uncompressed x86 kernel doesn't
> make sense, If you have a very fast boot device, then it is fully
> conceivable that an uncompressed kernel could boot faster than a
> compressed one.  I have seen a very large number of systems where the
> LZO compression boots at least twice as fast as gzip or bz2 (because
> the disks are fast enough that a few megabytes of size difference
> make much less of an impact than a slow decompressor).

I concur, the uncompressed kernel certainly makes sense in some cases.

If the kernel runs in an emulator, decompression could be slow.

If the kernel runs in a virtual machine, the kernel would need to be
decompressed separately for every virtual machine.  Reading from the
disk would be done only once if several virtual machines are started in
a short period of time.

-- 
Regards,
Pavel Roskin
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