building grub-2.05 with Xen support in C8 versus Buster, looking at gntdev.h

[Pry Mar <pryorm09@xxxxxxxxx>]

Hello xen-users,

http://git.savannah.gnu.org/cgit/grub.git/

I'm doing a build of latest grub-2.05 with the goal of making the
pvgrub2 images for x86_64-xen and i386-xen_pvh. These can be used to
boot domU VM in a variety of ways: from root symlinks, grub legacy
configs, or grub2 configs especially for pv and pvh types.

Pvgrub2 images from Buster:
grub-i386-qemu.bin
grub-i386-xen.bin
grub-i386-xen_pvh.bin
grub-x86_64-xen.bin

The images made in C8 worked as desired and gave useful output. The
Buster images failed silently. The C8 had build had hardening
undefined, so I tried that in Buster with no help.

What got success with Buster was noticing that the xen devel headers
were not the same with C8.

// headers in Buster
pbdeps$ sudo ls -al /usr/include/xen/
total 36
drwxr-xr-x  2 root root  4096 Jun  8 13:55 .
drwxr-xr-x 33 root root  4096 Jun  8 13:56 ..
-rw-r--r--  1 root root  3553 Apr 29 02:38 evtchn.h
-rw-r--r--  1 root root  2619 Apr 29 02:38 gntalloc.h
-rw-r--r--  1 root root 10647 Apr 29 02:38 gntdev.h
-rw-r--r--  1 root root  4206 Apr 29 02:38 privcmd.h

//headers in C8
(all same)
-rw-r--r--  1 root root 7322 Feb  4 18:09 gntdev.h

Owners of gntdev.h
// gntdev.h owner on C8
mockbuild@c80pv:~$ sudo rpm -qf /usr/include/xen/gntdev.h
kernel-headers-4.18.0-147.5.1.el8_1.x86_64

// owner on Buster
/pbdeps$ sudo dpkg -S /usr/include/xen/gntdev.h
linux-libc-dev:amd64: /usr/include/xen/gntdev.h

Since 2 years ago I was told that the Xen headers were already
installed with the OS and there is no need to install any supporting
xen-devel package.

Swapping in the C8 gntdev.h was a desperate move, but it got the job done.
What else could I do to avoid a bad gntdev.h in Buster?

cheers,