Re: [Xen-devel] pv-grub and grub.conf locations

[Steven Haigh <netwiz@xxxxxxxxx>]

On 7/11/2014 10:40 PM, Steven Haigh wrote:
> On 7/11/2014 10:19 PM, Stefano Stabellini wrote:
>> On Fri, 7 Nov 2014, Steven Haigh wrote:
>>> Hi Stefano,
>>>
>>> Sorry to hassle you directly - but I'm trying to figure out a use case
>>> of pv-grub to replace most pygrub configurations.
>>
>> No worries. I CC'ed xen-devel, because I think that this is an
>> interesting question that could be useful to other people too.
>>
>>
>>> I have two main locations where the grub config may live:
>>>     1) (hd0)/boot/grub/grub.conf or
>>>     2) (hd0,0)/boot/grub/grub.conf
>>>
>>> This depends if the DomU is created by something like the debian
>>> installer which refuses to install to a 'whole disk' - or say my EL6
>>> kickstart which installs to /dev/xvda as ext4 (which is easier to manage).
>>>
>>> From what I've been reading, there is no way to pass both of these to
>>> pv-grub and let it deal with whichever one exists.
>>>
>>> Interestingly, pygrub seems to search all paths to make this work - ie
>>> you only need to specify:
>>>     bootloader = 'pygrub'
>>>
>>> As I'm trying to generate generic config files, it makes life much
>>> harder to implement pv-grub as the loader (even though its preferred).
>>>
>>> Any thoughts on this?
>>
>> Unfortunately it doesn't look like there is a way to do that at the
>> moment. But I agree it would be useful and we might be able to make it
>> work for the next release (Xen 4.6).
>>
> 
> Well, from digging through the grub 0.97 documentation, it *may* be
> possible - however documentation on pv-grub seems to be very rare.
> 
> Interestingly, from the grub documentation:
> 13.3.11 find
> — Command: find filename
> 
>     Search for the file name filename in all mountable partitions and
> print the list of the devices which contain the file. The file name
> filename should be an absolute file name like /boot/grub/stage1.
> 
> Also:
> 13.3.6 configfile
> — Command: configfile file
> 
>     Load file as a configuration file.
> 
> It wouldn't be too hard to imagine a grub configuration script that
> could be loaded (somehow) into the 'extra' section of the DomU config
> that basically passes the output of 'find /boot/grub/grub.conf' to
> configfile $result and uses that to boot.
> 
> This may actually be possible already - but I haven't found any
> documentation that points to it or any configurations that have been
> published.
> 
> Any further feedback from anyone who has seen this may help out...

Interestingly, if this is a bug or not:

grubdom> debug
 Debug mode is turned on

grubdom> find /boot/grub/grub.conf

Error 15: File not found

grubdom>


-- 
Steven Haigh

Email: netwiz@xxxxxxxxx
Web: http://www.crc.id.au
Phone: (03) 9001 6090 - 0412 935 897

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