Re: XIP (Rev. 2)

[David Young <dyoung%pobox.com@localhost>]

On Tue, Nov 09, 2010 at 09:24:06PM +0200, Antti Kantee wrote:
> On Tue Nov 09 2010 at 12:47:11 -0600, David Young wrote:
> > On Tue, Nov 09, 2010 at 04:31:22PM +0200, Antti Kantee wrote:
> > > A big problem with the XIP thread is that it is simply not palatable.
> > > It takes a lot of commitment just to read the thread, not to mention
> > > putting out a sensible review comments like e.g. Chuq and Matt have done.
> > > The issue is complex and the code involved is even more so.  However,
> > > that is no excuse for a confusing presentation.  It seems like hardly
> > > anyone can follow what is going on, and usually that signals that the
> > > audience is not the root of the problem.
> > 
> > If the conversation's leading participants adopt the rule that they may
> > not introduce a new term ("pager ops") or symbol ("pgo_fault") to the
> > discussion until a manual page describes it, then we will gain some
> > useful kernel-internals documentation, and the conversation will be more
> > accessible. :-)
> 
> Those concepts are carefully documented, if nowhere else, at least in
> the uvm dissertation.

A dissertation is just the kind of documentation that I am *not* looking
for.  It's not written to answer practical questions about using UVM.

> Basically a pager is involved in moving things
> between memory and whatever the va is backed with (swap, a file system,
> "ubc", ...).

"What is a pager?" is a textbook concept that I don't expect for uvm(9)
to cover.  I do expect for uvm(9) to answer a question such as, "how do
I create a new virtual-memory range and install my own fault handler for
it?", "what are the arguments and return codes for pgo_get, pgo_put, and
pgo_fault?", "what are the public members of vm_page, if any?", or "what
are the public members of a uvm_object, if any?"

Dave

-- 
David Young             OJC Technologies
dyoung%ojctech.com@localhost      Urbana, IL * (217) 278-3933