Date: Sat, 30 Jan 1999 10:43:49 -0800 From: Mike Smith <mike@smith.net.au> To: Warner Losh <imp@village.org> Cc: small@FreeBSD.ORG Subject: Re: compressed executables in low memory environements Message-ID: <199901301843.KAA00963@dingo.cdrom.com> In-Reply-To: Your message of "Sat, 30 Jan 1999 01:52:22 MST." <199901300852.BAA75275@harmony.village.org>
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> > Has any thought (or work) been given to being able to run compressed > executables basically in place? Right now the gzip device in FreeBSD > does almost this, but requires the entire program to be decompressed > before running. What I had in mind would be something that would use > fixed length blocks (not optimal for compression, but not bad either) > so that they could be "paged" into uncompress memory easily? Yeah, Terry and I discussed this a while back. You need a couple of things for it to perform well: - A compression algorithm that compresses page-sized blocks of the original file and allows you to recover individual pages out of order. - A new object format that includes an index giving the offsets of the compressed data representing each of these pages. (You could do this with ELF.) You don't want to assume that you will be able to meet any particular compression quota; that forces you to pessimise your expectations. It's quite doable, subject to finding the right compression algorithm. -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-small" in the body of the message
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