Re: pvgrub2 and old grub menu.lst

[Andrey Borzenkov]

On Wed, Apr 2, 2014 at 12:43 PM, Michael Chang <address@hidden> wrote:
> On Tue, Apr 01, 2014 at 08:06:44PM +0400, Andrey Borzenkov wrote:
>> В Tue, 1 Apr 2014 15:46:22 +0800
>> Michael Chang <address@hidden> пишет:
>>
>> > While trying to boot xen pv guest with old grub config (menu.lst),
>> > the pvgrub2 loads it's menu successfully, but when you attemp to boot
>> > the kernel it failed with the following message.
>> >
>> >   error: couldn't load file /boot/vmlinuz-3.0.76-0.11-xen.
>> >   error: you need to load the kernel first.
>> >
>> >   Press any key to continue..."
>> >
>> > The kernel is there and boots fine with pygrub.
>> >
>> > After some investigation, it boils down to the menu.lst has explicitly
>> > set it's root device to (hd0,1) and therefore the root device is not
>> > recognized by pvgrub2.
>> >
>> > title Xen -- SUSE Linux Enterprise Server 11 SP3 - 3.0.76-0.11
>> >   root (hd0,1)
>> >   kernel /boot/vmlinuz-3.0.76-0.11-xen root=/dev/xvda2 resume=/dev/xvda1
>> > splash=silent showopts initrd /boot/initrd-3.0.76-0.11.xen
>> >
>> > I'd like to know whether old grub configuration is considered or planned
>> > to work with pvgrub2 ? And is it a viable suggestion to have (hdX,Y) a
>> > valid xen disk name because it's quite common in some existing configs ?
>> >
>>
>> I believe this technically should work; but this needs someone who
>> knows how Xen disks is mapped to hd number in legacy grub.
>>
>> It would be something like (completely untested)
>
> Thank you for the patch. I applied it and tried to test it. The
> virtdisks[i].handle never matched with num as it's id of the disk (on
> my system it is 51712).
>

As I said, completely untested :)

> Please pardon my ignorant, can num be the index to the virtdisks array
> to get the mapped xen disk ?
>

pv-grub additionally sorts by handle:
http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=stubdom/grub/mini-os.c;h=9d4bcc76d5f3e9907889948ee0dcea32e19c185b;hb=HEAD#l73

So to actually map pv-grub hdX we need to do the same.