Carrier Grade Linux/Gaps Alpha1

[Joe.MacDonald@xxxxxxxxxxxxx (MacDonald, Joe)]

Hey Greg,

On Mon, 2008-05-26 at 21:01 -0700, Greg KH wrote:

> On Sat, May 24, 2008 at 08:59:00PM +0200, Guillaume FORTAINE wrote:
> > Misters,
> > 
> > FYI :
> > 
> > http://www.linux-foundation.org/en/Carrier_Grade_Linux/Gaps_Alpha1

A little background for anyone unfamiliar with this particular page,
first.

After the CGL 4.0 spec was complete we'd [where 'we' means 'the version
4.0 editors and CGL tech board'] been expecting to take all the gaps and
put them into a database of some kind that would be used to generate
future versions of the documents.  The wiki page we're looking at now
was a second cut at putting together a format that would allow us to
collaboratively edit the requirements, but we're leaning away from that
now and back in favour of a full database.  We're hoping to discuss the
details of it at our next face-to-face meeting in Helsinki next week.


> {sigh}
> 
> Let's just pick one random "gap" right from the beginning:
>   	AVL.8.3 Parallel Driver Initialization During Startup
> 
> 	Priority: P3

And in case anyone on the list isn't clear what the priority levels are
for the CGL requirements, here's a quick cut at how we evaluated and
assigned them.

P1:  Widely adopted, commonly used, portable across multiple
architectures implementations that are either in mainline kernel, are
well-maintained patch sets (eg. features found in an external tree that
are unlikely to make it into mainline but many of the distribution
vendors integrate anyway) or active and well-maintained projects (eg.
remote collection of system logs).

P2 (other tech editors jump in here because I know I always get this one
wrong):  Commonly used and bundled with distributions but either of
limited application (eg. architecture-dependent features, requirements
tied to specific bootloaders, etc.) or not actively maintained.

P3: Items that have been identified as important to SCOPE from a carrier
grade operating system which have no current implementation available in
the community.

Obviously the P3 requirements are going to be the most contentious.  :-)


> 	Description: CGL specifies that, if multiple drivers are
> 	compiled into the Linux Kernel, the initialization or probing
> 	routines of those drivers execute in parallel. CGL further
> 	specifies that, if multiple drivers are to be loaded as modules,
> 	the driver modules are loaded in parallel. CGL further specifies
> 	that in either of these two cases, a driver is only initialized
> 	once its dependent drivers have initialized.
> 
> That's an interesting requirement.  What is supposed to be achieved by
> this?  Why is it a requirement?  What is supposed to happen if this is
> implemented?
> 
> Hint, it was implemented, went into a kernel.org kernel, and then later
> removed, does anyone want to tell me why you all want it back in?

By the time I joined the CGL WG this was already a requirement, so I
don't know the history behind it, but this is exactly the kind of
discussion we'd been hoping to have with everyone so we can properly
evaluate these sorts of requirements and have a constructive discussion
with SCOPE about them at our regular meetings.  The focus of the CGL
meeting next week is to review gaps like these, clean them up as best we
can, then hopefully get just this kind of feedback from people like
yourself.  We hadn't published the wiki link widely yet, though, because
the WG hasn't finished the editing process and we don't yet have our
database in place and we're very mindful that we don't want to waste
your time with items we can remove (or at least clarify) ourselves.

I don't remember when this was in and then removed from the kernel but I
can guess for reasons why it would've been.  Can you tell us, though,
the actual reasons?  Hard evidence for why this was a bad idea will
definitely make our lives (as in the folks who create the CGL spec and
who interact with SCOPE on a regular basis) easier.


Thanks.



Joe MacDonald, Member of Technical Staff, Wind River
direct 613.270.5750  mobile 613.291.7421  fax 613.592.2283   
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.linux-foundation.org/pipermail/lf_carrier/attachments/20080527/7f26b83b/attachment.htm 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: This is a digitally signed message part
Url : http://lists.linux-foundation.org/pipermail/lf_carrier/attachments/20080527/7f26b83b/attachment.pgp