Question On Initrd.img File From Images/pxeboot

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What format is the images/pxeboot/initrd.img file on the DVD ?

Its not gzip its not straight cpio What is it? I wish to change it.
I’m finding information on changing the gzip version of initrd but not the PXE one. If I do “file initrd.img” it just says data.


4 thoughts on - Question On Initrd.img File From Images/pxeboot

  • I ran into this also. It’s compressed using xz. You will probably need to be on an rhel6/CentOS6 system to manage the image.

  • Just grab the xz package.

    I roll initrds (for a custom pxe boot setup) on a CentOS 5.8 host. I’ve rerolled the initrd for 6.2 some time ago and you’ve reminded me to take care of 6.3 today.

    Name : xz Arch : x86_64
    Version : 4.999.9
    Release : 0.3.beta.20091007git.el5
    Size : 473 k Repo : installed Summary : LZMA compression utilities URL :
    License : LGPLv2+
    Description: XZ Utils are an attempt to make LZMA compression easy to use on free (as in
    : freedom) operating systems. This is achieved by providing tools and libraries
    : which are similar to use than the equivalents of the most popular existing
    : compression algorithms.
    : LZMA is a general purpose compression algorithm designed by Igor Pavlov as
    : part of 7-Zip. It provides high compression ratio while keeping the
    : decompression speed fast.


  • If you’re updating your CentOS 5.X installation regularly at all, xz and xz-libs should be automatically downloaded as a dependency for something, can’t quite remember what. Most of our 5.X machines have pulled it when updates are run weekly.