Re: [Xen-users] what does "initrd-2.6.32.9.img" contains

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Thu, May 13, 2010 at 11:52:55PM +0800, lei yang wrote:
>    On Thu, May 13, 2010 at 11:46 PM, Pasi Kärkkäinen <[1]pasik@xxxxxx> wrote:
> 
>      On Thu, May 13, 2010 at 11:32:17PM +0800, lei yang wrote:
>      >    On Thu, May 13, 2010 at 8:35 PM, Pasi Kärkkäinen
>      <[1][2]pasik@xxxxxx> wrote:
>      >
>      >      On Thu, May 13, 2010 at 04:40:33PM +0800, lei yang wrote:
>      >      >    Hi all
>      >      >
>      >      >    If I use nfsroot boot the xen dom0, I find it works well if
>      not use
>      >      >    initrd-2.6.32.9.img.
>      >      >
>      >      >    what does  "initrd-2.6.32.9.img" contains?
>      >      >
>      >
>      >      It's the "initial ramdisk" for Linux kernel. It contains (some)
>      driver
>      >      modules for the kernel,
>      >      and a script to load them and to mount the actual root filesystem
>      and
>      >      switch to it.
>      >
>      >      All the distros nowadays compile drivers as modules (ie. not
>      included in
>      >      the kernel itself),
>      >      and use the initrd image to load only the needed/required drivers
>      at
>      >      boot time.
>      >
>      >
>      >
>      >    Thanks Pasi, I have another question, why we need this initrd
>      ramdisk,
>      >    because we can put the kernel module in the dir "/lib" of rootfs,
>      if we
>      >    ignor the initrd, it should work
>      >
> 
>      Because you can't access the rootfs before you have the drivers loaded!!
>      initrd contains the drivers required to access the *rootfs*.
> 
> 
>    aha, Thanks, that's the good answer, today, I boot a dom0 without initrd
> 
>    gPXE> dhcp net0
>    DHCP (net0 00:15:17:b0:01:76).... ok
>    gPXE> kernel del/xen-4.0.0 module 17906/kernel  root=/dev/nfs rw
>    nfsroot=128.224.165.20:/export/17906/rootfs ip=dhcp console=ttyS0,115200
>    enforcing=0
>    gPXE> boot
> 
>    it boot well, maybe some drivers is not compiled "Y" not "M", I'm not sure
>    which kernel module is need before access rootfs
> 

If you're able to boot without initrd then your NIC and NFS drivers are
built-in instead of modules.

When booting from local disks you need to have the disk controller and 
filesystem
driver modules loaded from initrd, possibly also software-raid and lvm drivers.

-- Pasi

>    Thanks
>    Lei
> 
> 
> 
> 
>      -- Pasi
>      >    Lei
>      >
>      >
>      >
>      >      -- Pasi
>      >
>      >    --
>      >    "We learn from failure, not from success!"
>      >
>      > References
>      >
>      >    Visible links
>      >    1. mailto:[3]pasik@xxxxxx
> 
>    --
>    "We learn from failure, not from success!"
> 
> References
> 
>    Visible links
>    1. mailto:pasik@xxxxxx
>    2. mailto:pasik@xxxxxx
>    3. mailto:pasik@xxxxxx

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users