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d53bfb9201
Integrate zlib DFLTCC deflate compression to single volume dasd dumper using the existing s390 extended dump format. Compression takes place only if DFLTCC facility is available, otherwise dump is written uncompressed as before. First megabyte of memory is always written uncompressed and afterwards this area is used for zlib workspace and for the compression output buffer. The compression takes place in chunks of data of equal size (currently 1MB) and the offset of each compressed chunk is stored in the dump segment header. Since existing dump segment headers of 1 page size are used, we need to limit the maximum size of compressed dump segments. Chunk is written uncompressed in case of compression error or if deflate compression only makes it bigger. Thus every chunk of data is compressed separately and can be decompressed independently. The main reason for that is to enable zgetdump to make fast read seeks. Otherwise, zgetdump would need to decompress a big dump segment in the worst case to extract a single piece of data. Put compression related functions and structures to eckd2dump_zlib.c and eckd2dump_zlib.h Update zipl man page with the general information of zlib compression support. Signed-off-by: Mikhail Zaslonko <zaslonko@linux.ibm.com> Reviewed-by: Alexander Egorenkov <egorenar@linux.ibm.com> Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>