Fedora Ring 0 definition

[Brendan Conoboy]

On 09/02/2015 02:14 PM, Simo Sorce wrote:
> On Wed, 2015-09-02 at 13:57 -0700, Brendan Conoboy wrote:
>> On 09/02/2015 12:47 PM, Simo Sorce wrote:
>>> On Wed, 2015-09-02 at 15:31 -0400, Matthew Miller wrote:
>>>> On Wed, Sep 02, 2015 at 11:59:55AM -0700, Brendan Conoboy wrote:
>>>>> Re-sending this with a better title so people might read it ;-)
>>>>
>>>> Yes, thanks -- I admit to having skimmed over it in my mail-catchup
>>>> attempt.
>>>>
>>>>>> especially how the rings interact.  As a side note, everyone agreed
>>>>>> the word "rings" breaks down the further you get away from the center,
>>>>>> but nobody has come up with something better yet (Venns? Blobs?
>>>>>> Zones?).
>>>>
>>>> If people aren't gonna want to rename Rawhide to Bikeshed, then maybe
>>>> *this* could be called that. :)
>>>>
>>>>>> Right now the Fedora distribution is 1 ring, let's call it ring 1. The
>>>>>> distribution contains an operating system and numerous applications
>>>>>> that run on that operating system.  When we talk about defining ring 0
>>>>>> we're really talking about distinguishing between the operating system
>>>>>> and the applications that run on top of it.
>>>>
>>>> Speaking of bikesheds... we've traditionally defined the Fedora
>>>> operating system as *the whole thing*, so now calling a subset of that
>>>> the OS gives plenty of room for quibbling. I'm hoping to forestall that
>>>> by saying that regardless of that, we all know what you mean here. That
>>>> may be optimistic.
>>>>
>>>>
>>>>>> We want to go from this:
>>>>>> Ring 1: The Fedora Distribution
>>>>>> To this:
>>>>>>
>>>>>> The Fedora Distribution:
>>>>>> Ring 0: The Linux Operating System
>>>>>> Ring 1: The Applications and Stacks
>>>>>>
>>>>>> It seems quite modest, but working through the details on what this
>>>>>> means is hard.  What is an operating system in the Linux context? Ring
>>>>>> 0 will likely have the strictest set of policies of all the rings, so
>>>>>> we want to keep it as small as possible, but it is more than a minimal
>>>>>> install.  These are the traits of rings in general and ring 0 in
>>>>>> particular as I see it:
>>>>>>
>>>>>> 1. Ring 0 is a repository of rpm packages built in koji.
>>>>>>
>>>>>> 2. Ring 0 contains, but is not limited to, the minimal install of
>>>>>> packages to go from Power On to a login prompt.
>>>>
>>>> In my conception, the "is limited to" set was Ring 0, and the thing you
>>>> are calling Ring 0 was Ring 1, and then Envs and Stacks was Ring 2. I
>>>> can live with ajusting things; just noting. For the rest of this
>>>> message I will use your levels.
>>>>
>>>>>> 3. Ring 0 passes repoclosure on its own (Packages listed as hard
>>>>>> "Requires" in a ring 0 spec file are themselves are implicitly ring 0).
>>>>
>>>> *nod*
>>>>
>>>>>> 4. Ring 0 is not self hosting.  Packages listed in "BuildRequires" do
>>>>>> not need to be members of Ring 1.  This isn't ideal, but it's a
>>>>>> practical consideration.
>>>>
>>>> When you say Ring 1 here, you mean Ring 0, right?
>>>>
>>>>
>>>>>> 5. Ring membership is at the source package level, not the binary
>>>>>> package.  If one source package's binary/noarch sub-package is in ring
>>>>>> 0, all sub-packages are in ring 0.
>>>>
>>>> Hmmmm. Are we sure about that? That means that one can't, for example,
>>>> subpackage an optional feature with huge dependencies (or cascading
>>>> explosion of dependencies) to keep them from being pulled into Ring 0.
>>>>
>>>> If this is the case, are we open to having *separate* Ring 1 packages
>>>> built from the same source but with different options?
>>>
>>> This is what I replied to the original mail too, nobody answered ...
>>
>> I answered- did you miss it?
>
> Apparently never got it, I've had some annoying SPAM false positives
> recently that involved fedora lists posts (I also missed a chunk of
> flock mailing :-/)

Yeah, I found a big chunk of flock email in my spam folder as well 
*after* the event. Sigh.

Here's a pointer to the message:

http://www.spinics.net/lists/fedora-devel/msg213539.html

A quick cut&pate from that reply:

[blc]
 >> 5. Ring membership is at the source package level, not the binary
 >> package.  If one source package's binary/noarch sub-package is in ring
 >> 0, all sub-packages are in ring 0.
 > [simo]
 > Can you elaborate more on this point (5) ?
 >
 > I can totally see how a package may be critical and therefore 
deserve to
 > be in ring 0 and yet have optional features in terms of subpackages 
that
 > are not necessarily ring 0.
 > For example some library that offers optionally bindings for somewhat
 > rarely used languages (say ocaml). The subpackages for those bindings
 > shouldn't necessarily be ring 0.
 >
 > Or did I misunderstand the point ?

[blc]
Let's take gcc for example.  The gcc package produces numerous 
subpackages including various compilers and libraries.  One of those 
libraries, libgcc, is linked into nearly every dynamically linked ELF 
executable on your system (Run ldd to confirm), including /sbin/init. 
  Since we really want /sbin/init to function we need to include 
libgcc in ring 0.  Since ring membership is at a source level rather 
than a sub-package level, gcc is ring 0.  There are other good 
arguments for the executable-generating tools living in ring 0, but 
this one illustrates the point.

Ring policies might include things like how long the package is 
supported, what build system can generate it, what release cycle it is 
on, what the packaging guidelines are, what the updates rebase policy 
is, and so forth.  These types of policies apply to source rpms as a 
whole.  You can't apply one to gcc-c++ and another to libgcc.

I think the question you are posing might be, in the context of gcc, 
might be: Does gcc-g++ need to appear in the same repository as 
libgcc? IE, can we decouple what we build from what is presented to 
users?  If the threshold for must-include is repoclosure then no, we 
don't need to include gcc-c++, we only need to include libgcc and make 
gcc-c++ available elsewhere.  In talking to Langdon about this, he had 
the idea of "ring 0" and "ring 0 prime" where prime is ring 0 plus 
something.  We weren't sure what the something might be, but perhaps 
it could be the optional sub-packages.



-- 
Brendan Conoboy / Red Hat, Inc. / blc at redhat.com