PROBLEM: Compatibility problem with C++, i386 & ia64 platform

PROBLEM: Compatibility problem with C++, i386 & ia64 platform

[Joakim Bentholm XQ (AS/EAB)]

1. Compatibility errors when including <asm/system.h> with g++ compiler on i386 and ia64 platforms.


If you want to use the memory barrier macros mb(), rmb() and wmb(), as defined in <asm/system.h>.

On i386 platform:
This will work if you use gcc, but not in g++, since the name of the parameter in the __cmpxchg(...) is new, which the C++ compiler will not accept. (new_val might have been a better choice ;-)

Function header
---
static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
				      unsigned long new, int size)
---


On Itanium 2 platform:
Compiling on Itanium 2 works if you add som typedefs and a define, which is normally defined when __KERNEL__ is enabled. 

Prepended rows to the include of system.h
---
#define __pa(x) x
typedef long s64;
typedef int s32;
typedef unsigned long u64;
typedef unsigned int u32;
#include <asm/system.h>
---


Maybe the system.h is not supposed to be included outside the kernel?
Is there a less crude way of getting hold of the macros?

Best Regards/JB

--
Joakim Bentholm
joakim.xq.bentholm@ericsson.com

Re: PROBLEM: Compatibility problem with C++, i386 & ia64 platform

[Sam Ravnborg]

[Snipped - about C++ compatibility]

The Linux kernel philosofy is not to support any type of C++.
And kernel provided header files are not supposed to be included
from userspace - use a sanitized version instead.

Developing modules in C++ is not supported.

	Sam

Re: PROBLEM: Compatibility problem with C++, i386 & ia64 platform

[Alan Cox]

On Maw, 2004-11-23 at 12:54, Joakim Bentholm XQ (AS/EAB) wrote:
> Maybe the system.h is not supposed to be included outside the kernel?
> Is there a less crude way of getting hold of the macros?

Nobody has really done serious C++ work with the base kernel. Getting
things like interrupt safe C++ memory and exception handling is not
exactly trivial
stuff. As such the kernel isn't really designed to be C++ friendly so
there are various uses of names like "new" in the kernel.

Developing kernel modules with C++ probably isn't ideal but I don't see
any problem in fixing the users of variables like "new" if you want to
do it and submit tested patches to akpm@osdl.org.

Alan