about ppc <asm/string.h>

[HappyPhot]

Hi,

  Under linux kernel, the file /include/linux/string.h will include 
<asm/string.h>.
  But I didn't found "string.h" under "asm-ppc", my asm is link to asm-ppc
(CPU is ppc). This makes me compile some code failed.
  (kernel version 2.6.x)

  Anybody knows about this ? Why there is no string.h under "asm-ppc" 
directory.

thanks a lot,
/Phot