Re: compiling modules with gcc 3.2

[Jakub Jelinek <jakub@redhat.com>]

On Fri, Apr 25, 2003 at 03:46:15AM -0700, devnetfs wrote:
> --- Arjan van de Ven <arjanv@redhat.com> wrote:
> 
> Thanks for the quick reply :)
> 
> > > Either way why is this so? AFAIK gcc 3.2 has abi incompatiblities
> > > w.r.t. C++ and not C (which the kernel+modules are written in).
> > 
> > there are some cornercase C ABI changes but nobody except DAC960 will
> > ever hit those. 
> 
> what are these? i am just curious about the change as i dont
> see them (probably did not search hard) documented/listed on
> gcc site. C++ ABI changes have some mention on some sites, but 
> NOT on C ABI. 

If I remember well, long long bitfields, oversided bitfields, etc.

> so does this mean that: these workarounds now fixed in gcc 3.X?
> and its just that the workaround employed in kernel source (for 
> gcc 2.X) is different than the way gcc 3.X fixes them and hence 
> objects generated from gcc 3.X and 2.X (w.r.t kernel sources+modules)
> dont mix well?

There are couple of places in kernel which do things like:

#if (__GNUC__ > 2)
  typedef struct { } spinlock_t;
  #define SPIN_LOCK_UNLOCKED (spinlock_t) { }
#else
  typedef struct { int gcc_is_buggy; } spinlock_t;
  #define SPIN_LOCK_UNLOCKED (spinlock_t) { 0 }
#endif

Obviously you cannot mix modules/kernels using any structure like that.

	Jakub