From: Philipp Hahn <hahn@univention.de>
To: qemu-devel@nongnu.org
Cc: Saptarshi Sen <saptarshi.mrg@gmail.com>
Subject: Re: [Qemu-devel] Qemu Boot failure with /dev/ram0
Date: Fri, 11 Oct 2013 09:11:56 +0200 [thread overview]
Message-ID: <201310110911.56498.hahn@univention.de> (raw)
In-Reply-To: <CAG5Np+p15dGMco0tw5Gkv_cJAULApbxkbqW-RBCxc=LwQ14jSQ@mail.gmail.com>
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 hahn@univention.de
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prev parent reply other threads:[~2013-10-11 7:12 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-16 5:40 [Qemu-devel] Qemu Boot failure with /dev/ram0 Saptarshi Sen
2013-10-11 7:11 ` Philipp Hahn [this message]
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