UPX + linuxbios....

Eric W Biederman ebiederman at lnxi.com
Fri Sep 27 02:14:01 CEST 2002

Not long ago, I worked my way through the upx code, and figured
out what I needed to do to use it in another project.  And started
using that as the decompressor for etherboot.

Today I have gone through and replaced the copy from rom to ram
in crt0.base with a decompression step.  This allows me to compress
all of the C code when it is stored in the rom chip, and only
decompress it as it is copied to RAM.  The upx decompressor
is roughly 180 bytes.  And I get a compression ratio of about 2:1

When I start compiling in a lot of debug messages, or the intel
microcode updates this compressor gives me a lot more room
to work with.   I reduced my footprint on the E7500 port by 20KB :)

This interacts badly with my implementation of the cache as ram trick but 
that code wasn't stable enough to really trust. :(

And in theory since I am moving less data off of the rom chip things
should go even faster. 


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