diff options
Diffstat (limited to 'schulung_tools/notes/initrd.txt')
| -rw-r--r-- | schulung_tools/notes/initrd.txt | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/schulung_tools/notes/initrd.txt b/schulung_tools/notes/initrd.txt new file mode 100644 index 0000000..e88b20b --- /dev/null +++ b/schulung_tools/notes/initrd.txt @@ -0,0 +1,41 @@ +# +# For both initrd variants it is assumed the root filesystem files are +# located at /home/devel/rootfs ... +# + + +# To create the archive-based initial ramdisk: + +cd /home/devel/rootfs +find . | cpio -o -H newc | gzip -9c > ../initrd.cpio.gz + + +# To create the image-based initial ramdisk: + +dd if=/dev/zero of=initrd.img bs=4M count=1 +/sbin/mkfs.ext2 initrd.img +sudo mount -o loop initrd.img /mnt +sudo cp -a /home/devel/rootfs/. /mnt/ +sudo umount /mnt +gzip -9 initrd.img + + +# +# The image-based initial ramdisk is the old way of doing things. It +# really has no advantages. But it does have disadvantages: +# +# - the size if limited by the image +# - the size is limited by the kernel configurations +# (CONFIG_BLK_DEV_RAM, CONFIG_BLK_DEV_RAM_SIZE) +# - the kernel root= parameter must be set to /dev/ram0 +# - the real root filesystem must unmount it after pivot_root +# (which means the real root filesystem has knowledge of an initrd) +# +# The archive-based initial ramdisk has the following differences/advantages: +# +# - very simple to create (no root rights required!) +# - uses exactly as much RAM as needed (grows dynamically) +# - does not require any special boot arguments +# - does not need to be "cleaned up" after switch_root +# (the real root filesystem has no knowledge that an initrd existed) +# |