Re: [PATCH] local_irq_disable removal

Karim Yaghmour
2005-06-12T05:06:04Z

Daniel Walker wrote:
> My reasoning is that Linux doesn't run in ring 0 . That to me makes linux
> and ADEOS two different entities. That's my way of looking at it.
[snip]
> I haven't looked at the code, I would like to . I have read about
> the ADEOS implementation .

*WARNING*WARNING*WARNING*WARNING*WARNING*WARNING*WARNING*WARNING*

ok, now that I've got the attention of anyone reading this post,
here goes:

The paper entitled "Adaptive Domain Environment for Operating
Systems", which I published in February 2001 presents a design
*PLAN*. The actual implementation is based on this paper, but
differs *SIGNIFICANTLY* from it. Hence, read the paper to
understand how the ipipe works *ONLY*. All this stuff about
ring 0 / ring 1 was *NEVER* implemented.

To understand what's in the current *PATCH*, please read this
instead:
http://marc.theaimsgroup.com/?l=linux-kernel&m=102309348817485&w=2
Here's the relevant passage:
> The complete Adeos approach has been thoroughly documented in a whitepaper
> published more than a year ago entitled "Adaptive Domain Environment
> for Operating Systems" and available here: http://www.opersys.com/adeos
> The current implementation is slightly different. Mainly, we do not
> implement the functionality to move Linux out of ring 0. Although of
> interest, this approach is not very portable.
>
> Instead, our patch taps right into Linux's main source of control
> over the hardware, the interrupt dispatching code, and inserts an
> interrupt pipeline which can then serve all the nanokernel's clients,
> including Linux.

Again, Adeos does not play *ANY* ring tricks. It just hooks
onto the kernel's *EXISTING* cli/sti/int-delivery mechanisms
using a *PATCH*.

Hope this helps dissipate some misconceptions about what Adeos
is *TODAY*.

P.S.: Sorry Daniel, none of the above emphasis is directed
personally towards you. I just know from talking to quite a
few people that my original paper *CONTINUES* to *MISLEAD*
people about what Adeos currently is. So I just thought I'd
make it clear at this point for those interested.

Karim
--
Author, Speaker, Developer, Consultant
Pushing Embedded and Real-Time Linux Systems Beyond the Limits
http://www.opersys.com || karim@opersys.com || 1-866-677-4546