Re: error: not xen image / you need to load the kernel first

[Andy Smith <andy@xxxxxxxxxxxxxx>]

Hi,

On Mon, Aug 21, 2023 at 12:52:55PM +0100, George Dunlap wrote:
> On Thu, Aug 17, 2023 at 9:12 PM CamZie <camzie@xxxxxxxxxxxxxx> wrote:
> > We get the following error message everytime we boot the newest kernel:
> >
> >        error: not xen image.
> >        error: you need to load the kernel first.
> 
> Where are you seeing this error message?  I don't see either of those
> strings anywhere in the xen.git tree.

That error is coming from the Xen PV support in grub ("pvgrub"). It
doesn't support any of the advanced kernel compression formats like
LZ4 or ZSTD, so distributions like Ubuntu which went to LZ4 and
later ZSTD are not bootable using pvgrub.

So this is a (Xen PV support in) grub issue, not a Xen upstream
issue.

It's been quite a few years now and it doesn't look like anyone is
interested in adding support to pvgrub for these kernel compression
methods.

If possible OP should switch to PVH mode; pvhgrub seems to be done a
different (better?) way which makes use of other parts of grub for
loading kernels, so it supports whatever grub upstream supports.
LZ4 and ZSTD kernels are no problem there.

OP already discovered that extracting an uncompressed kernel out of
the domU kernel image does work, so that is the sort of thing that
will need to be done to boot these kernels if OP wants to continue
booting with pvgrub.

Cheers,
Andy

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