svn commit: r191276 - in head/sys: amd64/include arm/include i386/include ia64/include mips/include powerpc/include sparc64/include sun4v/include

[Robert Watson]

On Mon, 20 Apr 2009, Bruce Evans wrote:

>> +#ifndef CACHE_LINE_SHIFT
>> +#define	CACHE_LINE_SHIFT	6
>> +#endif
>> +#define	CACHE_LINE_SIZE		(1 << CACHE_LINE_SHIFT)
>
> This still has the bogus ifdef.  Overriding the definition is difficult to 
> do consistently even in a kernel with no modules, since CACHE_LINE_SIZE is 
> not a kernel option.  Overriding the definition makes negative sense since 
> the value is a maximum-maximum (possibly larger than strictly needed) so 
> that it can be constant.

OK, I've made this change.  My hope is that most applications don't resort to 
including sys/param.h and using CACHE_LINE_SIZE -- most will be able to query 
it at run-time using interfaces we don't yet have (such as sysconf(3) and some 
appropriate constant).  I also hope that most kernel consumers will be able to 
use a run-time tuned version (which we also don't yet have).

Robert N M Watson
Computer Laboratory
University of Cambridge