Should Xen be a sub-arch or a build option?

[Robert Watson]

On Mon, 22 Oct 2007, Warner Losh wrote:

> If it were me, I'd look at having it be a build option, much like PAE is a 
> build option.  PAE has a bigger impact on the i386 world than xen, and it is 
> only an option.  PAE breaks kernel ABIs, while xen doesn't (as far as I 
> know).  PAE changes the size of things like vm_addr_t and bus_addr_t.  I 
> think this would fit best with our current world view and sensabilities.

I have to admit that I find the novelty and simplicity of "options XEN" pretty 
appealing -- I also had been thinking only in terms of a sub-arch and the 
associated paperwork.  I guess the real question is what we lose by doing this 
-- will ps(1), vmstat(8), kgdb(8), etc, all work transparently across i386 and 
i386+xen?

Robert N M Watson
Computer Laboratory
University of Cambridge