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Subject: [Qemu-devel] Re: [PATCH] Add tar container format
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To: Alexander Graf <agraf@suse.de>
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-devel@nongnu.org, Christoph Hellwig <hch@lst.de>


> Bzip2 is supposed to be chunkable, but I haven't found anyone who did
> this yet and my knowledge in compression is pretty small.

Bzip2 proceeds in chunks of approximately 100-900 KB size.  However, the 
size is taken after an initial RLE compression pass.  So bzip2 is only 
chunkable if you remove the initial RLE compression---this means hacking 
the bzip2 executable (see ADD_CHAR_TO_BLOCK and add_pair_to_block) in 
bzip2's bzlib.c.

Using GIO may have been a good idea a few years ago, but it seems a bit 
overengineered given that the block layer of qemu works well and it is 
pretty complex.

Paolo