How to extract modern Ubuntu initramfs
Just to remember, there is an explanation here, from which the following directive can be taken:
(cpio -id; zcat | cpio -id) < /path/to/initrd.img
Similar Posts
Painful upgrade from Edgy x86_64 to Feisty x86_64
ByEtzionIf it works, don’t touch it. This is one of my mottoes. I have broken this rule just yesterday when I decided that I was too lazy to install Pidgin from source, and decided I wanted it to be installed directly from deb. Unfortunately, there was no pidgin deb for Edgy. None that I was…
Oreon (Centreon) issue with php pear
ByEtzionIt appears in some cases, for some pieces of software (anyone said “open source and poorly documented?”) that every installation has its own quirks and issues. It seems that following the same pattern is not always enough. It can be caused by the day you have selected to download and use the external component which…
RedHat / Centos Kickstart tweaks
ByEtzionKickstart is a great method of hands-free installation of RHEL/Centos (and other derived systems). Its power is in its easy interface and rather powerful %post scripting directives. Its weakness is in its lack of flexibility where it comes to package selection and various custom actions. On some cases, companies use web interface (usually home-made) which…
New version of Cacti, and using spine
ByEtzionA while ago, a newer version of Cacti became available through Dag’s RPM repository. An upgrade went without any special events, and was nothing to write home about. A failure in one of my customer’s Cacti system lead me to test the system using “spine” – the “cactid” new generation. I felt as if it…
RedHat 4 working cluster (on VMware) config
ByEtzionI have been struggling with RH Cluster 4 with VMware fencing device. This was also a good experiance with qdiskd, the Disk Quorum directive and utilization. I have several conclusions out of this experience. First, the configuration, as is: <?xml version=”1.0″?> <cluster alias=”alpha_cluster” config_version=”17″ name=”alpha_cluster”> <quorumd interval=”1″ label=”Qdisk1″ min_score=”3″ tko=”10″ votes=”3″> <heuristic interval=”2″ program=”ping vm-server…
RHEL4 tends to change network interfaces names
ByEtzionRHEL4 tends to change the names of network cards when there are more than one. If you had a NIC called eth0 during install time, it doesn’t mean that it will maintain that name after the first reboot. It could switch names with its friend, and be called now eth1, while the previous eth1 name…
5 Comments
Leave a Reply Cancel reply
This site uses Akismet to reduce spam. Learn how your comment data is processed.
I am working on Lubuntu 22.04, and either the lubuntu team creates the ramdisk differently, or the command is now out of date.
This works for me:
(cpio -id; cpio -id; zstdcat | cpio -id) < /path/to/initrd.img The ramdisk I am working with now has 2x uncompressed CPIO archives, prepending a "Z Standard" compressed main ramdisk.
They can modify it, however – how? Can you run the command ‘file’ on the initrd file? Or ‘lsinitrd’? It will give you a lot of details and insights.
In any case, on Ubuntu 22.0.4 my command works, and there is no reason to assume that this mechanism has changed. Just to be clear – your command failed on my test with the following output:
cpio: Malformed number
and
cpio: premature end of archive
Hi etzion, while I was initially confused by your response, I think I understand where the difference comes from. With my initrd I have 3 CPIO archives, the first 2 being microcode for AMD and Intel CPUs respectively – they each have their own CPIO archive. Then the third archive is the main initial ramdisk, encrypted Z standard encryption.
My ramdisk comes from the Lubuntu ISO. It is the ramdisk used to load the live environment. I assume the ramdisk you are using is for Ubuntu, installed on your computer? It would make sense to me that they would drop one of the first two microcode ramdisks, depending on what is applicable to the machine’s processor.
Thanks for your response, by the way you have some great info on your website. Thanks for what you do!
I understand. You were using the special LiveCD initrd. On systems which are on-disk, the initrd is created per the hardware configuration and layout of the system. Your note is good and important – and it exposes a structure including both microcodes as the same time, for both types of CPUs. When the system is installed on disk, it will integrate only the CPIO image for the relevant microcode. Makes a lot of sense.
I really appreciate the feedback. I have been collecting and sharing (and using it as an extended memory) for a long while. Some of it is still relevant even today 🙂
Thanks!