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Re: [Xen-devel] Proposal to allow setting up shared memory areas between VMs from xl config file

Hi there,

Thanks for your comments. They are all very insightful.

Having read through the discussions so far, I can draw the
following conclusions:

0. The syntax and semantics of the new config option should be more clearlly
    defined. And this actually depends on the following:

1. If we're going to make this project arch-neutral, then the manifestation
    of the frame numbers should also be arch-neutral;

2. Attributes such as readability, writability (and maybe even
    cacheability and shareability) should be able to be specified in the
    config files

3. We should allow users to specify the mfn of the shared pages as well. (but
    I think maybe we could just specify a memory zone (if we're dealing
    with NUMA) instead of a specific physical address).

4. (maybe in the future) Set up a notification channel between domains
    who are communicating through shared memory regions. The
   channel could be built upon PPI or SGI.

5. Clearify the ownership of shared pages, and thus the creation order.
    I thinks I've already clearify this in my proposal -- we just
treat the first domain
    created with the shared memory range as the owner.
    But specifying  this in the config file also makes sense. Then we'll have to
    enforced that the owner is created prior to all the "clients".

After talking to stefano, I'll try to first come out with a tiny but
working prototype
and do some evaluations on it. I'll not fully deny the possibility of using
the grants api as the final implementation choice.

This list might be incomplete. Please tell me if I missed or misunderstand any
important information.


Zhongze Liu

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