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Date:	Thu, 01 Nov 2007 18:59:24 -0700
From:	"H. Peter Anvin" <hpa AT zytor DOT com>
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Subject:	Re: Why "upx --brute" might be a bad idea...
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Robert Riebisch wrote:
> Hi!
> 
> Please read this thread at
> <http://www.bttr-software.de/forum/forum_entry.php?id=1220>, how UPXed
> binaries cause compile slowdowns.
> 

"upx --brute" and "upx --ultra-brute" runs a bunch of algorithms, and 
picks the smallest one, which may or may not be LZMA.  I don't know how 
they affect decompression speed, and it would be interesting to find out.

In particular, the NASM build robot 
(ftp://ftp.zytor.com/pub/nasm/snapshots/) appear to generate marginally 
smaller binaries with --[ultra-]brute than with --lzma --best, and I'm 
wondering where the difference comes from.  It would also be nice to 
know what algorithm it ends up using so I can tell it to use the same 
one every time, instead of trying them all every time taking time (a 
whopping minute every night ;)

	-hpa

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