Re: L4Ka::Pistachio code style

On Fri Nov 24, 2006 at 20:53:03 +0530, arnuld wrote:
>i have browsed the source code of L4Ka::Pistachio 0.4 (L4P). most of
>the source code in "kernel/src/" is written in this style:
>
>1.)  "x->y(z)"   : a struct pointer
>2.) pointers instead of refrences  :   at most places.
>
>it is C++ written in C style rather than the C++ design advocated by
>Stroustrup and other respected members of the C++ community . why
>L4Ka::Pistachio adopted this style & why it does not use "Standard
>Library, Class mechanism & Templates" at most places instead of that
>low-level C style. [1]

Because we don't want the overhead of virtual functions, and want to have
a precise understanding of the data structure layout and the code generated.

>i dont know C but i have done some C++ where i did some optimization
>of 2 programmes, one using "string" class & other using "malloc/free"
>& "string" class was as fast as "malloc/free" & i know Templates are
>"compile-time" mechanism, hence not they do not produce any run-time
>overhead.

They can create large code which significantly impacts on the cache.

>[1] i am not trying to start a flame-war. i only want to know the
>issues, whether technical or others, behind this decision. i am pretty
>much interested in microkernel based OSs & have read several papers &
>articles on HURD, L4 & Coyotos, Haskell, BitC, MINIX & Common Lisp. i
>was intersted in doing some contributions to a copyleft OS. 

L4 is not distributed under a copyleft license.

Benno