Control: tags -1 + moreinfo Hi Christoph,
> Just noted by coincidence, that even though I have set: > COMPRESS=zstd > and zstd is installed and even runs (seen in e.g. top utility) when running > update-initramfs -u > the files are in the end nevertheless plain cpio: > file /boot/initrd.img-5.10.0-7-amd64 > /boot/initrd.img-5.10.0-7-amd64: ASCII cpio archive (SVR4 with no CRC) I can see the same behaviour on my amd64 machine, but on my arm64 system 'file' identifies the initramfs images as zstd archives: /boot/initrd.img-5.10.0-6-arm64: Zstandard compressed data (v0.8+), Dictionary ID: None According to the last lines of /usr/sbin/mkinitramfs, there seems to be a non-compressed cpio at the top of your amd64's initrd.img which is followed by the zstd-compressed one. To validate my argumentation, please set 'COMPRESS=gzip' in '/etc/initramfs-tools/initramfs.conf', run 'update-initramfs -u' again and compare the sizes of the (probably) zstd-compressed one with the gzip-compressed one. On my amd64 machine, it looks like this: $ file initrd-*/* initrd-gzip-compressed/initrd.img-5.10.0-6-amd64: ASCII cpio archive (SVR4 with no CRC) initrd-zstd-compressed/initrd.img-5.10.0-6-amd64: ASCII cpio archive (SVR4 with no CRC) $ ls -hs initrd-*/* 36M initrd-gzip-compressed/initrd.img-5.10.0-6-amd64 28M initrd-zstd-compressed/initrd.img-5.10.0-6-amd64 . Kind regards, Nicolas PS: Does anyone know, how to extract the second (aka compressed) cpio archive from the combined initrd.img?
