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Re: [RFC] split floppy support off biosdisk

From: Bean
Subject: Re: [RFC] split floppy support off biosdisk
Date: Tue, 17 Jun 2008 22:52:26 +0800

On Tue, Jun 17, 2008 at 10:39 PM, Javier Martín <address@hidden> wrote:
> El mar, 17-06-2008 a las 11:06 +0800, Bean escribió:
>> AFAIK, lzma decompresser don't need intermediate buffers, it operates
>> directly on the input and output buffer, for example, the lzmadecoder
>> in coreboot:
> I think you didn't see the intermediate buffer because it is hidden in
> the Probs field passed through the decoderstate struct. I've googled my
> way through the net to find what the hell "probs" mean, and I still
> don't understand ten contiguous lines of the LZMA code. What I could
> find is that
> provides the decoder with about 32KiB of "scratchpad" memory and will
> reject decompressing files which "require" (as somehow indicated by the
> first 5 bytes of the LZMA stream) more than that. I don't know if that
> space is used for dictionaries, trees, forests or a Matrix full of
> virtual monkeys hitting keys at random until the decompressed stream is
> achieved, but its size seems to impose constraints at the time of
> compression (probably a maximum -n level) that merit investigation.
> PS: have you tested the performance of other compression algorithms like
> gzip-deflate (much simpler) or bzip2 (near LZMA for small files but with
> less memory requisites)?


I think memory is not a problem here, as grub2 can use upper memory:

src = raw data
dest = 0x100000
buf = dest + kernel_size


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