Re: [Xen-users] Booting pv-ready distro installer.iso as Xen PV DomU drops to grub prompt?

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Thu, 2015-04-09 at 18:01 -0700, lyndat3@xxxxxxxxxxxxx wrote:
> 
> On Thu, Apr 9, 2015, at 04:59 PM, Mark Pryor wrote:
> > You have a hybrid config. To go pv do:
> > to boot into a pv install, use these ./boot/x86_64/{initrd-xen,vmlinuz-xen}
> > 
> > as kernel / ramdisk in the test.cfg. So copy the pair locally off the ISO.
> 
> IICU, for booting with pvgrub2 -- which is what I'm working towards -- that's 
> incorrect IIUC.
> 
> This
> 
> kernel = "/usr/lib/grub2/x86_64-xen/grub.xen"

Where did you get this binary from?

Are you following
https://blog.xenproject.org/2015/01/07/using-grub-2-as-a-bootloader-for-xen-pv-guests/
 or something else?

> is supposed to be sufficient.

For an already installed guest, yes, although it depends somewhat on the
distro supporting pvgrub2 if you want to chainload as opposed to using
the dom0 supplied grub binary only.

But, I think you are trying to start the installer itself using pvgrub,
is that right?

My short term "I just want something working" suggestion would be to try
adapting
http://wiki.xen.org/wiki/Debian_Guest_Installation_Using_Debian_Installer#CD-ROM_installation
 for SuSE (basically switch the paths to bootloaders_args to suite) and do the 
install that way using pygrub and then switch to pvgrub2 once things are 
installed.

[...]
>       error: file `/boot/x86_64/grub2-efi/x86_64-xen/echo.mod' not found.
>       error: can't find command `linuxefi'.
>       error: file `/boot/x86_64/grub2-efi/x86_64-xen/echo.mod' not found.
>       error: can't find command `initrdefi'.
> 
> In the iso
> 
>       find /mnt/iso | egrep -i "linuxefi|initrdefi|echo.mod"
> 
> there's none of those.

My (completely wild) guess is that those will be found in an EFI System
Partition stored elsewhere in the ISO image (in an el torito boot sector
or something).

However even if they were present they will be for the native version of
grub baked into the ISO and not the pvgrub2 which you've provided
externally, so you would want to ensure that you included those modules
into the grub image (i.e. list them when running grub-mkimage).

I'm also not entirely sure if the linuxefi/initrdefi commands will
support launching a PV kernel, since they likely expect an EFI image.
During the install I would expect the distro to notice that you aren't
running EFI and for the installed system to end up with the non-EFI
stanzas in grub.cfg. Or maybe linuxefi is smart enough to fallback to
the other method if the given file isn't an EFI PE image, that would be
rather useful.

> (1) How do I get the DomU config to recognize the configfile without
> forcing a visit to the grub prompt?

Passing it on the guest command line might work (it did with pvgrub1,
not sure about 2).

If not then the path needs to be baked into the grub binary you are
using, i.e. by passing appropriate parameters to grub-mkimage when you
make your grub.xen.


> (2) Not sure what to do about the missing linuxefi/initrdefi/echo.mod ...
> 
> LT
> 
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