Hello, On Monday 16 September 2013 07:40:08 Saptarshi Sen wrote: > I want to use a ram disk as a block device for my kernel.( i am > measuring file io on ram ) > > I am trying to boot a kernel from using /dev/ram0. However I am getting > "No root Device found" > > qemu-system-x86_64 -m 8G -hda disk.img -kernel vmlinuz-3.10.0-rc6 > -initrd initramfs-3.10.0-rc6.img -append "root=/dev/ram0 selinux=0 > enforcing=0 rw" -vnc :0
Perhaps you're mixing "Initial*RamFS*" and "Initial*RootDisk*"? Your filename "initramfs" indicates you're going for the former, but your "root=/dev/ram0" is required fror InitRD. InitRamFS is a (compressed) CPIO archive, which is extracted to a dynamically growing "tmpfs" by the kernel. InitRD is a (compressed) ext2/3/4/jfs/xfs/whatever filesystem, which is backed by a fixed portion of you RAM; you probably need to explicitly specify a "ramdisk_size=250000" parameter to be large enougth to contain the uncompressed file-system. If the size is too small, you will have a corrupt FS where you also get the error you mention above. Sincerely Philipp -- Philipp Hahn Open Source Software Engineer h...@univention.de Univention GmbH be open. fon: +49 421 22 232- 0 Mary-Somerville-Str.1 D-28359 Bremen fax: +49 421 22 232-99 http://www.univention.de/ Director:Peter H. Ganten HRB 20755 Amtsgericht Bremen UID:DE 220 051 310