Re: [25% OT] C library integral part of OS/kernel???

From: Mark McIntyre (markmcintyre_at_spamcop.net)
Date: 03/08/05 

Date: Tue, 08 Mar 2005 11:56:16 +0000

On Tue, 08 Mar 2005 11:49:08 +0530, in comp.lang.c , Ravi Uday
<raviuday@gmail.com> wrote:

>Dan Pop wrote:
>> In <ln1xaswcp0.fsf@nuthaus.mib.org> Keith Thompson <kst-u@mib.org> writes:
>>
>>>My guess is that there's only one implementation of the strlen()
>>>function, and that it's callable either from the kernel or from user
>>
>> Your guess is typically wrong: a kernel is a freestanding program
>> and it doesn't rely on any external library,
>>
> So, when an executable gets built, then there are two copies of C
>library functions

Maybe, maybe not. Dan's guess is probably as wrong as Keiths, and both are
just as possibly right. Indeed if you read what Keith said, its not even
incompatible with Dan's comment.

For example the kernel may provide a service to allow userland apps to call
its version of the C library functions. Or the two may both use an
physically external library and there may be one shared copy in memory, or
two separate copies one in userspace and one in kernelspace, or there may
be two or more physical copies of the library on disk - consider that you
probably have executables built with microsoft, gnu and borland C, each
providing their own library, possibly more than one, if different versions
of the compiler were used. 

-- 
Mark McIntyre
CLC FAQ <http://www.eskimo.com/~scs/C-faq/top.html>
CLC readme: <http://www.ungerhu.com/jxh/clc.welcome.txt>
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