Runtime Altivec detection

Albert Cahalan albert at
Sun Mar 9 15:01:47 EST 2003

For those of you needing to get at ELF note info
to determine CPU features and other things, here
is the code procps-3.1.x has been using. You'll
need the appropriate ID code; here I use AT_CLKTCK
to determine USER_HZ. Pass the ID code into this
function, and you get back the ELF note value.

#ifndef AT_CLKTCK
#define AT_CLKTCK       17    // frequency of times()

#define ERROR_CODE 42  // choose something better!

extern char** environ;

// for ELF executables, notes are pushed before environment and args
static unsigned long find_elf_note(unsigned long findme){
  unsigned long *ep = (unsigned long *)environ;
    if(ep[0]==findme) return ep[1];
  return ERROR_CODE;

// Usage:
// Hertz = find_elf_note(AT_CLKTCK);


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