Re: mirage support for dynamically loaded modules

[Anil Madhavapeddy <anil@xxxxxxxxxx>]

On 8 Sep 2013, at 20:25, Andrew Lekar <sam.and.tetris@xxxxxxxxx> wrote:

> Hello everyone.
> 
> Is it possible to support dynamically load ocaml modules in mirage? So that I 
> do not rebuild entire mirage kernel but make it once and add additional 
> drivers later. What are the steps required to make it possible? I guess to 
> make it work I should implement filesystem support, bytecode interpreter or 
> ocaml compiler in mirage.

Hi Andrew,

It depends which backend you're thinking of.  In Xen, we have some patches to 
further make the address space immutable post-boot (by dropping the ability to 
alter the guest page tables or switch CR3).  In that case, you can't do dynamic 
loading by design.

However, without this patch, and with a suitable filesystem, network or vchan 
source for the dynamic module, you could do dynamic loading.  The real question 
is why you'd want that at all, given it's easier to recompile a Mirage instance 
and redeploy it rather than go through all the trouble of dynamic loading.  In 
many ways, that's the whole point of the Xen backend ;-)

-anil