Re: [Xen-devel] GRUB2 missing multiboot2 patches?Re: Only 1 CPU was detected

[Michael Young <m.a.young@xxxxxxxxxxxx>]

On Thu, 28 Sep 2017, Hongjiang Zhang wrote:

> > -----Original Message-----
> > From: Stefan Bader [mailto:stefan.bader@xxxxxxxxxxxxx]
> > Sent: Friday, September 29, 2017 4:49 AM
> > To: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>; Hongjiang Zhang
> > <honzhan@xxxxxxxxxxxxx>
> > Cc: Juergen Gross <jgross@xxxxxxxx>; xen-devel@xxxxxxxxxxxxxxxxxxxx
> > Subject: Re: GRUB2 missing multiboot2 patches?Re: [Xen-devel] Only 1 CPU
> > was detected
> >
> > On 28.09.2017 16:03, Konrad Rzeszutek Wilk wrote:
> > > On Thu, Sep 28, 2017 at 02:45:38PM +0000, Hongjiang Zhang wrote:
> > > > > > (XEN) ACPI Error (tbxfroot-0218): A valid RSDP was not found
> > > > > > [20070126]
> > > > > Uuh, that is rather bad, I guess.
> > > I am going to assume this is due to not having:
> > >
> > > b4d709b6e Use grub-file to figure out whether multiboot2 should be
> > > used for Xen.gz a8e0f1adf Fix util/grub.d/20_linux_xen.in: Add
> > > xen_boot command support for aarch64
> > >
> > > In the grub that he is using (Ubuntu?)
> > >
> > > In other words he is using 'multiboot' instead of 'multiboot2'
> > If this is Ubuntu, my expectation is that this would require Xen 4.9 (which is
> > part of 17.10 but not yet released) and work on grub2 (which I  will very
> > unlikely have the time for). Debian has not yet moved to Xen 4.9, so I would
> > doubt that it would work there either.
> If Xen 4.9 does not work either, shall I try CentOS 7.13 instead? Or which 
> Linux distribution is recommended?
I think Fedora 27 (currently in beta) is almost there (for x86_64 anyway). 
It does have xen 4.9, but some manual steps are needed to get grub2 
working using multiboot2. These are
* edit the grub.cfg file to use multiboot2 and module2 rather than 
multiboot and module
* install the grub2-efi-x64-modules package and copy multiboot2.mod and 
relocator.mod from /usr/lib/grub/x86_64-efi to
/boot/efi/EFI/fedora/x86_64-efi/ (which you probably need to create)
* add insmod multiboot2 to the relevant section in the grub.cfg file with 
the other insmod lines.
Also watch out for useless sections in the grub.cfg file for a xen config 
file rather than for xen itself.
I recently got xen working doing the above including running a domU guest, 
but gdm didn't start and I haven't had a chance to work out if that is 
related or not.
        Michael Young

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