Re: [INFO] Kernel strict versioning
From: Franco \"Sensei\"
Date: Thu Apr 14 2005 - 11:56:57 EST
David Lang wrote:
some config changes are additions, some redefine things.
you are mistakeing the .config file for a symbol table.
No I'm not confusing. As long as the .config has an influence on the
makefiles I get different symbols names.
for example if you compile a kernel with SMP=y you get different code
then if you compile with SMP=n
if you have the same kernel version on identical machines, but with the
SMP option different on the two different machines you cannot use the
same module binary on both of them.
Of course, but It's cleare that machines with SMP are different from a
simple mono-cpu.
It's not an issue talking about smp vs. not-smp. Let's talk about a
machine: it's useless arguing about Cray while I'm talking about a
simple environment.
Every kernel has always the distinction about smp. So it's not a big
problem.
you would have an ABI for that kernel image, compiled with those
options, and with that compiler. if you change any of those things then
your modules won't work (you have a different ABI
Of course, as I stated, it's a distro's care to use the same gcc and
same switches....
what you are missing is that nobody has any interest in supporting a
kernel ABI, even within a single kernel version. there are just too many
advantages to changeing fundamantal things in the kernel depending on
the config options.
An advantage is the total freedom about the code. Ok, I know. But as
long as the kernel grows, in size and in its use, something more should
be considered. ABI is a step forward companies and people like me in
handling linux easily. API and data structure stability should be
something in mind, since breaking compatibility from 2.6.8 to 2.6.8.1
causes big troubles to anyone who's mantaining many machines. And if you
are in big environments, you probably use modules which are not in
vanilla, and will never be, like OpenAFS.
Finding a bug in the kernel source and patching it, must be a careful
step, because if I have to mantain 100 machines, and I know that
applying the patch will result in a broken kernel modules, I'm not happy
with it. I must go manually on each machine, apply the patch, recompile
the modules... Makes me think about NOT applying the patch.
I don't know why the default location for the modules, but again you are
assuming that you CAN have a single vmlinuz-2.6 kernel file for all
machines of a given arch.
you can't.
I think we can. Freedom in developing source code is not necessarily
stealing bricks from someone's feet :)
there are just too many config options that change the internals of the
kernel (locking, function call formats, CPU type optmizations, etc) for
you to just have one.
Source compatibility is there. Now, you're talking about issues which
are not your buisness: a binary distribution must take care of how the
kernel it's compiled. As long as it uses the same gcc and switches, it's ok.
Practically, if suse has kernel-2.6.A and kernel-modules-2.6.A it knows
how they're compiled, and they work everywhere. Of course, it has also
kernel-2.6.A-SMP and its modules.
When 2.6.B is released, using ABI will just result in another
compilation, creating the kernel with additions and patches, and
distributing them. Modules .A should work on .B, like I do with OpenAFS,
Every kernel update shouldn't break the magic :)
but 2.6.11.7 is not nessasarily binary compatable with 2.6.11.7, let
alone something drasticly different (say 2.6.11.6)
Sure, because it's not designed to be so.
I just see advantages on ABI, and I think it's not bad talking about it...
--
Sensei <mailto:senseiwa@xxxxxx> <pgp:8998A2DB>
<icqnum:241572242>
<yahoo!:sensei_sen>
<msn-id:sensei_sen@xxxxxxxxxxx>
Attachment:
signature.asc
Description: OpenPGP digital signature