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Re: Deltarpm xz problem with PPC generated rpms?



On Mon, 2009-09-14 at 12:30 -0400, Bill Nottingham wrote:
> Andreas Schwab (schwab redhat com) said: 
> > > 2. xz generates different compressed files when run on different
> > > architectures
> > 
> > The problem is that the encoder uses different hash functions depending
> > on the endianess.  The hash functions are defined in
> > liblzma/lz/lz_encoder_hash.h, and are based on the values in
> > lzma_crc32_table[0].  This table is different between big end little
> > endian.
> 
> Not having looked at the algorithm... *why*? Is it really that big
> of a difference?

I've been talking to the xz developer on IRC, and he says it's really
not a huge difference.  He sounds amenable to changing big-endian
compression so it uses the little-endian CRC32 table.

He said you'd need a new single-dimension CRC32 table that would only be
used when doing the big-endian build.

To be honest, though, this is all way over my head.

Jonathan

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