Re: [PATCH 1/3] change clone_flags type to u64

[Andi Kleen <andi@firstfloor.org>]

> I guess that was a development rationale. 

But what rationale? It just doesn't make much sense to me.

> Most of the namespaces are in 
> use in the container projects like openvz, vserver and probably others 
> and we needed a way to activate the code.

You could just have added it to feature groups over time.

> 
> Not perfect I agree.
>  
> > With your current strategy are you sure that even 64bit will
> > be enough in the end? For me it rather looks like you'll
> > go through those quickly too as more and more of the kernel
> > is namespaced.
> 
> well, we're reaching the end. I hope ! devpts is in progress and
> mq is just waiting for a clone flag.

Are you sure?

>  
> > Also I think the user interface is very unfriendly. How
> > is a non kernel hacker supposed to make sense of these 
> > myriads of flags? You'll be creating another 
> > CreateProcess123_extra_args_extended() 
> > in the end I fear.
> 
> well, the clone interface is a not friendly interface anyway. glibc wraps 
> it

But only for the stack setup which is just a minor detail. 

The basic clone() flags interface used to be pretty sane and usable 
before it could overloaded with so many tiny features.

I especially worry on how user land should keep track of changing kernel
here. If you add new feature flag for lots of kernel features it is
reasonable to expect that in the future there will be often new features.

Does this mean user land needs to be updated all the time? Will this
end up like another udev? 

> We will need a user library, like we have a libphtread or a libaio, to

That doesn't make sense. The basic kernel syscalls should be usable,
not require some magic library that would likely need intimate 
knowledge of specific kernel versions to do any good.

> but we still need a way to extend the clone flags because none are left.

Can we just take out some again that were added in the .25 cycle and
readd them once there is a properly thought out interface?  That would
leave at least one.

-Andi