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    SubjectRe: Initramfs from existing vmlinuz
    >>> On 2008/12/24 at 01:37 PM, "Martin Schlemmer" <>
    >>>> On 2008/12/24 at 01:34 AM, Willy Tarreau <> wrote:
    >> On Wed, Dec 24, 2008 at 12:28:53AM +0200, Martin Schlemmer wrote:


    >>> I had a bit of an accident, and wondered if somebody already had to try to
    >> extract the initramfs image from an existing vmlinuz?
    >>> I did try google, but either my search terms was not right, or nobody
    >> really touched on the subject before, because all the results mostly dealt
    >> with an external image.
    >>> Any advice will be appreciated.
    >> yes, it happens to me from time to time.
    >> You first have to extract and uncompress the ELF image from vmlinuz. For
    >> this, look for the gzip signature 1F 8B 08 in your vmlinuz, and feed all
    >> data starting from this point to zcat. Either you do the same on the
    >> resulting file -and you may find several compressed images- or you simply
    >> pass it through "objdump -h". It will show you a .init.ramfs section. Use
    >> the fourth field as the file offset, and dump from that position. You'll
    >> find your initramfs, likely starting with 1F 8B 08 since it's supposed
    >> to be compressed with gzip.
    >> You need an hex editor, dd, zcat and objdump for this. It's not much
    >> complicated once you have the tools, but it might require a few attempts
    >> before finding the right image (I tend to find config.gz before initramfs).
    > Appreciated, I should be able to go from here now - just getting the starting
    > point is sometimes the main issue.

    Simple Perl script to do above in case anybody might find it useful in the future.


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