could someone tell me how names of platform specific cpp predefines are
chosen?

basically, going through some of the xfree source (from their cvs), they
have some source that reads:

#ifdef _LP64
# if defined(__sparcv9)
#  define       _MACH64_NAME            "sparcv9"

i understand that _LP64 comes from the sysv ABI (right?), but where did
__sparcv9 come from?  netbsd has __sparc_v9__.  i'm curious if i should
change the x source or ask toolchain-masters about adding __sparcv9.

guelah [27] gcc -dM -E - < /dev/null
#define __arch64__ 1 
#define __sparc64__ 1 
#define __NetBSD__ 1 
#define __SIZE_TYPE__ long unsigned int 
#define __GNUC_MINOR__ 95 
#define __PTRDIFF_TYPE__ long int 
#define __sparc_v9__ 1 
#define __GNUC__ 2 
#define __sparc__ 1 
#define __ELF__ 1 
#define _LP64 1 

thanks.