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
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