>> Please, stop top-posting.  It makes it almost impossible to follow the
>> discussion when responding to your text.

Sorry.

>> I'm a little confused about what you think running the kernel in user
>> mode as a client of another kernel will achieve.  You don't think that it
>> will somehow make executables compiled for one processor run on another,
>> do you?  That would involve binary translation of the entire compiled
>> executables -- no user-mode operating system I am aware of does anything
>> like that.

I do not want to run one platform kernel as a client of another
kernel. I want to know the feasibility of creating a platform
independent user mode NetBSD; that is:

Creating the "user mode NetBSD" running on top of a platform isolation
layer [implemented on the host NetBSD]. That thing would be useful to
have the same user-mode-kernel compilable on all the NetBSD supported
platforms. In that way, with no further effort, any NetBSD platform
will have its "user mode NetBSD" running on top of it (e.g. x86 user
mode NetBSD running on top of x86 NetBSD; amd64 user mode NetBSD
runnign on top of amd64 NetBSD, and so...)

On User Mode Linux, I have read that the kernel requests done by the
guest OS are trapped by some hooks installed on the host machine,
those hooks are x86 specifics; that is why I ask for the feasibility
of a kernel isolation .