On Tue, 2005-11-22 at 06:46 +0200, MHD.Tayseer wrote:
[...]
> well .. the "unraliable guide to kernel hacking" sais that there are the
> following gnu extentions in the linux kernel:
>
> * Inline functions
Std C as such. But the kernel needs certain inline functions to be
always inlined (or reported as an error). And this is then also a
gcc-ism.
> * Statement expressions (ie. the ({ and }) constructs).
Are they always necessary or could it be solved with inline functions, functions,
do { ... } while(0) constructs?
> * Declaring attributes of a function / variable / type (__attribute__)
`#define __attribute__(x)` kills it. If killing is always a solution, is
another question (for functions, it is always a solution, for struct's
probably not).
> * Labeled elements
C99
> * typeof
gcc-ism
> * Zero length arrays
C99
> * Macro varargs
ANSI-C since ages
> * Arithmetic on void pointers
I believe C99, common since ages
> * Non-Constant initializers
I believe C99
> * Assembler Instructions (not outside arch/ and include/asm/)
Always AFICS compiler-specific.
> * Function names as strings (__FUNCTION__)
Std C sionce ages.
> * __builtin_constant_p()
gcc-ism - IOW Compiler-specific.
> is there more/less of those extensions now ? the document mentioned
> above is dated 2000 and i think life has changed so much inside the
> linux kernel since then...
Yes. Also the (newly at that time) C-99 standard is quite complete in
gcc-3.latest and gcc-4.*
> another question .. is there a known work around of those extensions to
> turn them into Ansi C?, or such an extensions are hard to be done under
Yes: Look at the code and what it should do, reformulate it, test it and
sent it as patch to lkml.
> ansi C .. i mean that it may be trivial to move a declaration or an
> expression two or three lines before .. is it trivial as text/syntax
Some probably yes.
> modifications or there are extensions that are based on a special gcc logic?
Also some of this type - see above.
> and if i wanna use cygwin .. i know that this question may now be asked
> here but can i call windows executable (the compiler in my case) from
> cygwin without recompiling/modifying it ?
In practice, you can only look which parts bite you and investigate if
it makes sense to fix them for your project or in general.
Bernd
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