On Sun, Apr 03, 2005 at 04:01:19PM +0400, Artem B. Bityuckiy wrote: > > >For instance for JFFS2 it's absolutely incorrect since it breaks > >compatibility. Incidentally, JFFS should create a new compression > >type that doesn't include the zlib header so that we don't need the > >head-skipping speed hack. > > Anyway, in JFFS2 we may do that "hack" before calling pcompress(), so it > isn't big problem.
It still makes sense to use a negative window bits for JFFS since it means that you don't have to calculate the adler checksum in the first place AND you don't have to store the zlib header/trailer on disk. BTW, that hack can only be applied when there is no preset dictionary. Although the Linux implementation of JFFS probably never used a preset dictionary, it is theoretically possible that someone out there may have generated a JFFS image which contains a compressed stream that has a preset dictionary. In that case if you don't set the window bits to a postive value it won't work at all. > >Yes, I'd love to see a patch that makes windowBits configurable in > >crypto/deflate.c. > > I wonder, do we really want this? Yes since the the window bits determines the compression quality and the amount of memory used. This is going to differ depending on the application. > Imagine we have 100 different compressors, and each is differently > configurable. It may make cryptoAPI messy. May be it is better to stand > that user must use deflate (and the other 99 compressors) directly if he > wants something not standard/compliant? Each crypto/deflate user gets their own private zlib instance. Where is the problem? Cheers, -- Visit Openswan at http://www.openswan.org/ Email: Herbert Xu ~{PmV>HI~} <[EMAIL PROTECTED]> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
