initrd images created from kickstart

Update: initrd files are now 'xz' archives.



I wondered whether a kickstart of a RHEL/CentOS distro would provide a customised initrd image for the hardware it was being installed on. To check this, I compared the initrd from a server with a particular (Marvell) SAS disk controller with another server without that controller.

initrd images are gzipped cpio files, so to compare the two, I copied each initrd to another location, so as not to interfere with needed boot files, moved each to a filename with a '.gz' extension, then gunzipped them and ran 'cpio -t < initrd_file_name' to list the files. The SAS disk controller kernel module was present in the initrd from the host that had that particular hardware, but not on the other host which didn't. It wasn't present in the kernel image (vmlinuz) on either, though it was present in config as a loadable module, so would have to be in the initrd, since it needs a filesystem to load from, presumably:

CONFIG_SCSI_MVSAS=m