Re: RE: RE: [Xen-users] Why creating DomU failed (seems it is duetoLVM)

["Zhang Binbin" <binbinzh@xxxxxxx>]

Hi, Mats,

And more info:
After I modified init script in DomU's initrd, it can boot successfully.
it is that i modified:
        mount -o defaults --ro -t ext3 /dev/root /sysroot
to 
        mount -o defaults --ro -t ext3 /dev/sda1 /sysroot
it seems DomU loader just can't find out which is the root device.

I don't know why it works, so I checked the mails before, and still can't know 
why...

Best,
Binbin 

======= 2006-12-13 20:40:29 you wrote:=======

>> -----Original Message-----
>> From: Zhang Binbin [mailto:binbinzh@xxxxxxx] 
>> Sent: 13 December 2006 12:22
>> To: Petersson, Mats
>> Subject: Re: RE: [Xen-users] Why creating DomU failed (seems 
>> it is due toLVM)
>> 
>> I can't understand using the same kernel(i.e. 2.6.16-xen), 
>> why Dom0 boots up smoothly, but DomU can't, if it is a driver 
>> missing problem.
>
>No, and I don't think that's the post I was actually commenting on.
>Since you seem to have snipped the original post I was commenting on,
>the original context I was commenting on isn't in this post... 
>
>That sounds like some other problem - particularly since DomU doesn't
>actually touch any of the hardware directly (unless you specifically add
>pci_hide to Dom0 and assign the device using pci = ... In the
>configuration of DomU). 
>
>If your initrd is the same as that of Dom0, then it wouldn't have the
>frontend drivers that the para-virtual device is required to use (unless
>you're using a HVM domain, in which case you shouldn't just copy the
>original Xen installation, but use a standard non-xen kernel for the
>DomU). 
>
>Note that initrd should contain the drivers necessary to boot the
>system, and that's different for Dom0 and DomU, since DomU uses the
>para-virtual frontend/backend driver pair (where the backend driver is
>in Dom0 and translates the request from DomU into a reasonable system
>request for Dom0 to perform the right operation on the "device" that
>DomU uses). 
>
>--
>Mats
>
>
>> 
>> Thanks. 
>> 
>> >Creating an initrd file isn't rocket surgery in itself
>> >
>> >Making a system boot when you haven't got the right drivers can be a
>> >pain in the posterior... 
>> >
>> >If you know what drivers you need to make the system boot and you're
>> >changing your config file to make that work, you may just as 
>> well skip
>> >the part of making something a module - it doesn't ACTUALLY help
>> >anything to have a module instead of a built-in driver. 
>> >
>> >On the other hand, if you don't have a clue what driver you actually
>> >need, and you're adding drivers "wholesale", you probably 
>> don't want to
>> >bloat the kernel by adding all of your drivers as "builtin", 
>> even if it
>> >saves you a bit of hassle by not creating an initrd. 
>> >
>> >It's often a good idea to start by using a simple setup - LVM, RAID,
>> >SCSI all add extra complications and more drivers are needed. Some of
>> >which may not work in a particular permutation of Xen + Dom0! If you
>> >can't make the machine boot in a complex setup, you may want to try a
>> >simpler setup before you try reconfiguring the kernel. 
>> Obviously, if you
>> >use LVM, you'll need the relevant "lvm modules" either builtin (my
>> >recommendation) or as a module when you build the initrd. 
>> >
>> >Carefull inspection of "dmesg" and any other "boot output" 
>> will also be
>> >useful. "lspci" is a good hint. 
>> >
>> >Note also that if you build Xen on one machine, and install 
>> on another,
>> >you'll need to do "depmod" as well as "mkinitrd" - and if 
>> you're copying
>> >individual files, make sure you copy the modules to the right place
>> >under /lib/modules/ - it happens automagically if you copy the whole
>> >.../dist directory, but I sometimes try to cheat by copying 
>> individual
>> >files, and it's been known to "fail". 
>> >
>> >--
>> >Mats
>> >> 
>> >> -- 
>> >> Steven
>> >> 
>> >> 
>> >> _______________________________________________
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>> >> Xen-users@xxxxxxxxxxxxxxxxxxx
>> >> http://lists.xensource.com/xen-users
>> >> 
>> >> 
>> >> 
>> >
>> >
>> >
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>>                      
>> 
>> 
>> 
>> 
>> 
>> 
>> 

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