Messages in this thread | | | From | Rob Landley <> | Subject | Re: [PATCH] skip initramfs check | Date | Mon, 21 Nov 2005 09:04:46 -0600 |
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On Monday 21 November 2005 00:23, Marcelo Tosatti wrote: > Hi Rob, > > Query: is the problem that a big initramfs image is being unpacked more > > than once, or is unpacking an empty initramfs image (134 bytes) causing a > > significant delay? > > The problem is a big non-initramfs RAMDISK image (used for root mountpoint > on this particular embedded platform), that is decompressed more than once: > > - during the initramfs check, which fails because it is not initramfs. > - during the real RAMDISK decompression to memory. > > > I'm fairly certain that back in 1990 I could unzip 134 bytes on my 33 mhz > > 386 running dos in a fraction of a second. What's the use case here? > > So the issue is not the empty initramfs image (which BTW could probably > be made unecessary?), but a 10Mb RAMDISK image being decompressed by a > 48Mhz PPC, which takes quite a few seconds. > > Need to rework the patch to use a __setup option as Andrew suggested.
It sounds to me like is the initial check (which is just giving a thumbs up/thumbs down "is this an initramfs", correct?) only needs to decompress the first page or so of data to make this determination. A quick glance at the code seems to imply it's just checking the header and the first entry, so 4k should be plenty for that.
Some variant of lib/zlib_inflate... Ouch, bit of a mess there. Hey Matt: you know this area. Is it feasible to do some kind of:
deflate_init(whatever) deflate_next_x_bytes(source *, dest *, length)
To grab a the first X bytes from the initramfs image?
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