Message-ID: <425EF2A3.1070007@tin.it>
Date: Thu, 14 Apr 2005 17:45:55 -0500
From: "Franco \"Sensei\"" <senseiwa@tin.it>
Reply-To: Sensei <senseiwa@tin.it>
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To: Horst von Brand <vonbrand@inf.utfsm.cl>
CC: David Lang <dlang@digitalinsight.com>, Krzysztof Halasa <khc@pm.waw.pl>,
       Adrian Bunk <bunk@stusta.de>, linux-kernel@vger.kernel.org
Subject: Re: [INFO] Kernel strict versioning
References: <200504142034.j3EKYqmS005113@laptop11.inf.utfsm.cl>
In-Reply-To: <200504142034.j3EKYqmS005113@laptop11.inf.utfsm.cl>
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Horst von Brand wrote:
>>No I'm not confusing. As long as the .config has an influence on the 
>>makefiles I get different symbols names.
> 
> Nope.

I don't understand. The .config drives the kernel build, I don't get XFS 
functions and names if I don't compile it. I have different symbol 
names... At least, that's what I understand... and that's what 
happens... Never the same names on different kernels.

> And kernels compiled with one compiler are different than those compiled
> with another. And if you have preemption they are different. Don't forget
> about clasic i386 vs i486 vs ... vs i686 (spinlocks generate different
> code!). Then let's consider memory split: 2/2, 3/1, 3.5/0.5, ... Now throw
> in assorted debugging options. On some architectures you have several
> possible (reasonable!) page sizes.

Yes, ok.

> Define "simple environment". Even Red Hat (they are /very/ interested in a
> single kernel image, as it cuts down testing and bug tracking etc!) ships
> half a dozen different kernels, tailored for different configurations. And
> you'll find external modules (like for NTFS) compiled separately for each
> of them.

Yes, but as long as you keep with the same configuration, no problem 
should arise in changing the kernel version.

> Or having /your/ standard kernel on all 100 machines, compile once and copy
> around. No need for /me/ to run your exact same configuration.

I probably expressed myself badly. I don't mean anyone having the same 
configuration... why on earth should it be?

>>Source compatibility is there.
> 
> Sort of.

I hope! :)

> And A doesn't have some options I'd like, and others you loathe.

That's why you recompile, but why should you throw your other modules 
not included in the kernel release?

>>             creating the kernel with additions and patches, and 
>>distributing them. Modules .A should work on .B,
> 
> Iff nothing changes. That isn't usually the case.

That's weird... why should things really change so drastically if the 
external interface still remains the same? It's probably a matter of 
abstraction...

> The problem is that giving that guarantee costs developer time and
> flexibility. The gain (given that source for recompilation is freely
> available) is so minuscule that the consensus is that it just isn't worth
> any extra hassle /at all/.

Ok.

> And the decision to design thusly is completely conscicious, it is not a
> random "it just turned out this way by mistake".
> 
>>I just see advantages on ABI, and I think it's not bad talking about it...
> 
> I see many disadvantages to ABI, and it wouldn't be bad to look at them too.

I'd really like to know... I'm naive? Yes :) Of course, other than 
``more work'', but technical disadvantages...

-- 
Sensei <mailto:senseiwa@tin.it> <pgp:8998A2DB>
        <icqnum:241572242>
        <yahoo!:sensei_sen>
        <msn-id:sensei_sen@hotmail.com>

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