Non-PAE Dom0 kernel for running Ethos

[W. Michael Petullo]

I am trying trying to run a research OS named Ethos as a DomU
paravirtualized guest. Ethos does not yet support 64-bit or PAE, so I
need to build a non-PAE Dom0 kernel. I am having trouble doing this. Here
is what I tried:

1. Edit Michael Young's kernel.spec as follows:

# kernel-PAE is only built on i686.
%ifarch i686
%define with_pae 0
%define with_up 1
%else
%define with_pae 0
%endif

2. Build an RPM using "rpmbuild -ba --target i686 --with xen --without
debuginfo kernel.spec."

When try to boot my Dom0 kernel, Xen complains:

(XEN) elf_xen_note_check: ERROR: Will only load images build for the
generic loader or Linux images

Do I need to recompile Xen to go non-PAE?

See also https://bugzilla.redhat.com/show_bug.cgi?id=543190, unable to
build custom i686 non-pae kernel.

[M A Young]

On Sat, 27 Mar 2010, W. Michael Petullo wrote:
> Do I need to recompile Xen to go non-PAE?

It may not be that simple, because I am not convinced that xen supports 
non-PAE any more so you might need an older version, and that won't be 
compatible with recent pv_ops kernels.

Michael Young

[Pasi Kärkkäinen]

On Sat, Mar 27, 2010 at 08:53:02PM -0500, W. Michael Petullo wrote:
> I am trying trying to run a research OS named Ethos as a DomU
> paravirtualized guest. Ethos does not yet support 64-bit or PAE, so I
> need to build a non-PAE Dom0 kernel. I am having trouble doing this. Here
> is what I tried:
> Edit Michael Young's kernel.spec as follows:
>
> # kernel-PAE is only built on i686.
> %ifarch i686
> %define with_pae 0
> %define with_up 1
> %else
> %define with_pae 0
> %endif
> Build an RPM using "rpmbuild -ba --target i686 --with xen --without
>
> debuginfo kernel.spec."
>
> When try to boot my Dom0 kernel, Xen complains:
>
> (XEN) elf_xen_note_check: ERROR: Will only load images build for the
> generic loader or Linux images
>
> Do I need to recompile Xen to go non-PAE?
>
> See also https://bugzilla.redhat.com/show_bug.cgi?id=543190, unable to
> build custom i686 non-pae kernel.

Xen doesn't support non-PAE PV guests anymore.
I think Xen 3.2 was the last release to support non-PAE 32bit Paravirt guests.

Xen 3.4 and 4.0 definitely require 32bit PV guests to be PAE.

Xen HVM guests can be non-PAE.

-- Pasi