[CentOS] Re: Centos 4.4 ?

Sun Jul 30 09:46:49 UTC 2006
Karanbir Singh <mail-lists at karan.org>

Leonardo Vilela Pinheiro wrote:
> As an Enterprise operating system, CentOS provides software seamless 
> compatibility (if this can be called compatibility) inside the same 
> release (as Centos-4, or Centos-3, or Centos-2). Correct me if I´m wrong.

yes, this is correct. However, you might be more in 'sync' with reality 
by looking at this issue from a slightly different angle... the aim is 
that as packages move Release's through the lifecycle of a distro 
release ( eg. CentOS - 4 ) , the aim is not break either the ABI ( so 
your own apps function right ), the config file formats and expected 
behavior ( so your dont break config's ), and the filesystem layout ( so 
things continue to stay where they started off with ).

And this is maintained even when Packages move through their own release 
cycle ( eg. in C-4.4 mozilla has been replaced with the Seamonkey suite, 
but whatever you may have built against mozilla-nss and nspr will 
continue to work fine, with no need for a rebuild ).

> I know that if Intel (or whatever) releases a driver for CentOS 4.1, one 
> may think that it must be a new driver, possibly unstable. But let´s 

it will be unstable, but thats not the only thing, I would trust the 
distro vendor to have done a lot more stability testing with various 
install options and environments than Intel ( or any hardware vendor ) 
would have. In most cases the hardware vendor is only testing on 1 
architecture, and never on a continuous basis ( when was the last time 
intel had a driver for each kernel release from upstream ? ). However, 
its a mixed bag, both these people - h/w vendor and distro vendor - need 
to work together in the Linux scape, to make sure the user gets the best 
possible experience, support and functionality.( drifting OT ? )

> suppose a vendor gives me a driver which is new but completely stable 
> (just suppose, because this is just a conceptual question). Will this 
> driver be compatible with every (forward and/or backward) "sub-versions" 
> of CentOS 4 ? 

CentOS-4 is the distro, I would presume that the driver is kernel 
defendant mostly. Kernel updates, while they do happen at release cycle 
update, also take place between these release cycles. And to answer your 
question, yes - the Kernel's abi does not change. If it broke, report it 
as a bug.

If the driver has userland dep's - its upto the hardware vendor to 
ensure that the driver works for all release cycle's. There is 
absolutely nothing that the distro vendor can do in such cases. Having 
said that, I've not yet seen anything break in this manner.

What you also might want to keep in mind is that drivers within the 
distro kernel are updated and new drivers added in. So its possible, 
what while you needed an external Vendor driver to make some h/w 
function properly with 2.6.9-5.EL kernel, the driver was then included 
in the distro supplied, 2.6.9-11.EL.

Once you look at things from a slightly larger perspective, the 
kernel/driver issue falls into place.

HTH

-- 
Karanbir Singh : http://www.karan.org/ : 2522219 at icq