Re: [PATCH v2] stubdom: remove caml-stubdom

[Edwin Torok <edwin.torok@xxxxxxxxx>]

> On 22 Nov 2023, at 10:06, Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx> wrote:
> 
> On 22/11/2023 7:21 am, Juergen Gross wrote:
>> diff --git a/CHANGELOG.md b/CHANGELOG.md
>> index c341c9d0bf..bbb3cd5beb 100644
>> --- a/CHANGELOG.md
>> +++ b/CHANGELOG.md
>> @@ -14,6 +14,8 @@ The format is based on [Keep a 
>> Changelog](https://keepachangelog.com/en/1.0.0/)
>>      for IPIs and Physical addressing mode for external interrupts.
>> 
>> ### Removed
>> +- caml-stubdom has been removed. It didn't build since 2014, so nobody seems
>> +  to care.
> 
> May I suggest some different phrasing.
> 
> "caml-stubdom.  It hasn't built since 2014, was pinned to Ocaml 4.02,
> and has been superseded by the MirageOS/SOLO5 projects."
> 
> Also, one last ping to anyone Ocaml folks for any comment whatsoever.
> 

I'm fine with removing it, seems to predate the Lwt based Mirage, and the way 
to cross-compile OCaml to unikernels is completely different now.

I think the latest way to use Mirage under Xen is to use Solo5 (which has Xen 
support and gives you a PVH domain).
https://mirage.io/blog/announcing-mirage-39-release
"The Xen backend has been re-written from scratch to be based on Solo5, and now 
supports PVHv2 on Xen 4.10 or higher, and QubesOS 4.0."

The mirage version of xenstore is here (a functor that can be instantiated on 
both Unix and Unikernel implementations and doesn't depend on Irmin): 
https://github.com/mirage/ocaml-xenstore
And I think the Unikernel instantiation of the Xenstore Server functor is here 
https://github.com/djs55/ocaml-xenstore-xen/blob/master/xen/src/server_xen.ml, 
but probably needs to be updated to work with newer versions of Mirage. I 
haven't got around to trying it out yet.

I never tried to use the unikernel build inside the Xen tree, it seems to be 
completely undocumented so I wouldn't know where to start.

The new way is shown here, and dune has some builtin support to make this 
easier: https://mirage.io/blog/2022-03-30.cross-compilation

Best regards,
--Edwin