Don't archive as lzma if you don't want lzma, remove the "--format=lzma" parameter. hth Lucian -- Sent from the Delta quadrant using Borg technology! Nux! www.nux.ro ----- Original Message ----- > From: "Mircea Husz" <mirceahusz at yahoo.com> > To: "CentOS mailing list" <centos at centos.org> > Sent: Wednesday, 31 January, 2018 16:51:20 > Subject: [CentOS] How is initrd.img packed and compressed? > Hi, > > In order to work around a known upstream bug I needed to add a udev > rule to pxeboot initrd.img on CentOS 7. > > The process is straightforward: > 1 - extract the pxeboot initrd.img to a new directory > 2 - add the udev rule needed to fix the bug > 3 - pack and compress it back in initrd.img format > > The resulting updated image works, it fixes the upstream bug and life > is good. But although it works, it's not > the same format as the original initrd.img that ships with the distro. > I would like to know the proper incantation > used to package initrd.img > > Now for the specifics. The original image: http://mirror.steadfast.net/ > centos/7.4.1708/os/x86_64/isolinux/initrd.img > is extracted: /usr/lib/dracut/skipcpio initrd.img | xzcat | cpio -i -d > and after adding the needed udev rule, it gets packed and compressed as > follows: > > find . 2>/dev/null | cpio --quiet -c -o | xz -9 > --format=lzma >"~/patched-initrd.img" > > Now for the difference. FIrst the original distro image: > # file initrd.img > initrd.img: xz compressed data > > # file patched-initrd.img > patched-initrd.img: LZMA compressed data, streamed > Without the --format=lzma flag it fails to boot. > > Does anyone know how this is done properly ? > > Thanks, > -Mike > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos