On Fri, Jun 22, 2012 at 2:49 PM, AFT <aftnix@xxxxxxxxx> wrote: > > Hi, > > My source is from 2.6 git tree. In LDD3 its said that a logical address > is mapped to physical address and vice versa by the macros __va() and > __pa(). > > In my source tree they are defined as follows: > > <include/asm-generic/page.h> > > #define __va(x) ((void *)((unsigned long) (x))) > #define __pa(x) ((unsigned long) (x)) > > > I'm not actually understanding how these "cute" looking casting is > performing "address mapping". I thought address mapping involves more > complex operations. See the comments at the beginning of the file you quoted: /* * Generic page.h implementation, for NOMMU architectures. * This provides the dummy definitions for the memory management. */ For arch-specific code try looking, for instance, at arch/x86/include/asm/page.h . Hope this helps, Vlad _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
