Pkg xen devel - Feb 2022 - Bug#1006418: Add stub domain support

Package: src:xen
Version: 4.14.3+32-g9de3671772-1~deb11u1
Severity: wishlist

There are numerous references to "stub domains" in the information
about
Xen.  Given the benefits, it would be nice to have the functionality.

Notably qemu and xenstored are stated to be functional in stub domains.
I'm under the impression having xenstored in a stub allows domain 0 to
do a restart/kexec.  Having qemu in a stub adds protection for domain 0.

Initial experimentation indicated the default Xen build setup tries to
download the stubdom source during build.  This could be a challenge.


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Hello Everyone,

Just my 2c's: maybe instead of trying to enable the somewhat outdated 
Mini-OS based stubdomains: 
https://wiki.xenproject.org/wiki/Device_Model_Stub_Domains we should 
rather try to implement support for Linux based stubdomains: 
https://wiki.xenproject.org/wiki/Linux_stub_domains. As IMHO this could 
be done as a special flavor of the linux kernel + a custom initramfs, I 
add the debian-kernel mailing list.

Please share your thoughts.

Thank you and best regards,

Geza

Not a proper In-Reply-To since that message ended up /somewhere/ and I'm
thus going back to the bug DB for this reply.


I guess I'm neutral-ish on Linux versus Mini-OS for doing stub domains
for Debian on Xen.  I suspect development on Xen's Mini-OS isn't all
that
active.  On the flip side due to its limited requirements, Mini-OS might
not need much updating.

My major concern is can current Linux kernels be made small enough for
this to be worthwhile?  I've done some small Debian domains and they
really want a minimum of 192MB of memory, which seems a bit large.

Really the big issue seems to be someone simply needs to play with this
a *lot* in order to figure the thing out.  The information which is out
there isn't easy to understand.

I suspect the simplest may be to examine Qubes OS as they have figured
the thing out.


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