Messages in this thread | | | Date | Wed, 3 May 2006 18:38:14 +0200 (MEST) | From | Jan Engelhardt <> | Subject | Re: [RFC] Advanced XIP File System |
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> What is it?: > - Borrows much from CRAMFS with Linear XIP patches
Apropos borrowing: borrow the compression from Squashfs.
> I've heard people say, "XIP is stupid. Why on earth would I use > expensive slow flash instead of cheap fast RAM?" > [...] If I > take libfoo.so which is about 2MiB and throw it in JFFS2, it > compresses to about 1MiB in flash. If I store libfoo.so as an XIP > file (uncompressed) in XIP CRAMFS or AXFS it takes up 2MiB of flash. That is > 1MiB extra flash for XIP. But the JFFS2 version would need > 2MiB of RAM to store that library when used while the XIP system uses > 0MiB. That means XIP uses +1MiB of flash and -2MiB of RAM for > libfoo.so. So for any extra flash used for XIP, it can save twice > that amount of RAM. The end result can be lower cost systems on the > small end. The secret is to choose what to make XIP and what to > compress on flash.
If 2 MB of RAM are cheaper [as you say] than 1 MB of Flash, where's the advantage when XIP uses more flash?
Jan Engelhardt -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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