CentOS - Jan 2018 - Xen hypervisor on CentOS 7.4 with modern UEFI server not booting from grub

I checked and secure boot is turned off.

Jonathan brings it exactly to the point: we have to face UEFI because
legacy mode is fading out, if I enable legacy mode I can't even boot
anymore through the network (PXE) as these newer network cards can
only boot PXE with UEFI.

In the mean time I have installed Ubuntu 17.10 with Xen and I was
lucky to see that this combination works with UEFI even Xen.


On Wed, Jan 31, 2018 at 2:12 PM, Johnny Hughes <johnny at centos.org>
wrote:
> On 01/30/2018 04:23 PM, John Naggets wrote:
>> Hi,
>>
>> I installed CentOS 7.4 on a modern Lenovo ThinkSystem SR630 server
>> which uses UEFI. So far so good CentOS 7.4 works fine so then I went
>> on to install the Xen hypervisor by following the instructions from
>> the wiki (https://wiki.centos.org/HowTos/Xen/Xen4QuickStart).
>>
>> Unfortunately when I reboot after having installed the xen package the
>> system does not boot into "CentOS Linux, with Xen hypervisor"
from the
>> grub menu prompt. I get the following error:
>>
>> Loading Xen 4.6.6-8.el7 ...
>> error: can't find command `multiboot'.
>> Loading Linux 4.9.75-29.el7.x86_64 ...
>> error: can't find command `module'.
>> Loading initial ramdisk ...
>> error: can't find command `module'.
>>
>> Press any key to continue...
>>
>> The problem which I encounter here is exactly the same issue as
>> described for Fedora in the RedHat bugs:
>> https://bugzilla.redhat.com/show_bug.cgi?id=1286317 with the exception
>> that for me it's CentOS 7.4 and that the workarounds as described
in
>> that bug do not work.
>>
>> Does anyone know how I can make my CentOS boot with the Xen hypervisor
>> using UEFI?
>>
>> Thank you very much for your help.
>>
>
> Usually not an issue with UEFI .. but with Secure Boot
>
> You need to make sure Secure Boot is off.  It is sometimes called Legacy
> Booting turned on, etc.
>
>
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Once upon a time, John Naggets <hostingnuggets at gmail.com>
said:
> Jonathan brings it exactly to the point: we have to face UEFI because
> legacy mode is fading out, if I enable legacy mode I can't even boot
> anymore through the network (PXE) as these newer network cards can
> only boot PXE with UEFI.
UEFI PXE is different than BIOS PXE and needs to download different
software from the TFTP server.  I use syslinux for BIOS PXE, but it
doesn't seem to work with UEFI PXE so I use grub2 (I use the secure boot
shim from Fedora to support as many setups as practical).  You can have
both available at the same time (takes a DHCP tweak).

Just like the early days of BIOS PXE however, UEFI PXE clients don't
always seem to do the right thing.  I have an Intel NUC (7th gen), and
it always fails with UEFI PXE.

-- 
Chris Adams <linux at cmadams.net>

Hi Chris,

For completeness just wanted to mention that it is the first time I
see in newer servers that it is not possible to PXE boot from the
network using legacy mode (BIOS). It seems like the NICs are missing
the required piece of code for that as all 4 NICs of that server fail
to boot legacy PXE with the following message:

!PXE structure was not found in UNDI driver code segment.

Best,
J.

On Wed, Jan 31, 2018 at 9:06 PM, Chris Adams <linux at cmadams.net>
wrote:
> Once upon a time, John Naggets <hostingnuggets at gmail.com> said:
>> Jonathan brings it exactly to the point: we have to face UEFI because
>> legacy mode is fading out, if I enable legacy mode I can't even
boot
>> anymore through the network (PXE) as these newer network cards can
>> only boot PXE with UEFI.
>
> UEFI PXE is different than BIOS PXE and needs to download different
> software from the TFTP server.  I use syslinux for BIOS PXE, but it
> doesn't seem to work with UEFI PXE so I use grub2 (I use the secure
boot
> shim from Fedora to support as many setups as practical).  You can have
> both available at the same time (takes a DHCP tweak).
>
> Just like the early days of BIOS PXE however, UEFI PXE clients don't
> always seem to do the right thing.  I have an Intel NUC (7th gen), and
> it always fails with UEFI PXE.
>
> --
> Chris Adams <linux at cmadams.net>
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