3480   const int page_size = Aix::page_size();

  3481   const int map_size = page_size;

  3482 

  3483   address map_address = (address) MAP_FAILED;

  3484   const int prot  = PROT_READ;

  3485   const int flags = MAP_PRIVATE|MAP_ANONYMOUS;

  3486 

  3487   // Use optimized addresses for the polling page,

  3488   // e.g. map it to a special 32-bit address.

  3489   if (OptimizePollingPageLocation) {

  3490     // architecture-specific list of address wishes:

  3491     address address_wishes[] = {

  3492       // AIX: addresses lower than 0x30000000 don't seem to work on AIX.

  3493       // PPC64: all address wishes are non-negative 32 bit values where

  3494       // the lower 16 bits are all zero. we can load these addresses

  3495       // with a single ppc_lis instruction.

  3496       (address) 0x30000000, (address) 0x31000000,

  3497       (address) 0x32000000, (address) 0x33000000,

  3498       (address) 0x40000000, (address) 0x41000000,

  3499       (address) 0x42000000, (address) 0x43000000,

  3500       (address) 0x50000000, (address) 0x51000000,

  3501       (address) 0x52000000, (address) 0x53000000,

  3502       (address) 0x60000000, (address) 0x61000000,

  3503       (address) 0x62000000, (address) 0x63000000

  3504     };

  3505     int address_wishes_length = sizeof(address_wishes)/sizeof(address);

  3506 

  3507     // iterate over the list of address wishes:

  3508     for (int i=0; i<address_wishes_length; i++) {

  3509       // Try to map with current address wish.

  3510       // AIX: AIX needs MAP_FIXED if we provide an address and mmap will

  3511       // fail if the address is already mapped.

  3512       map_address = (address) ::mmap(address_wishes[i] - (ssize_t)page_size,

  3513                                      map_size, prot,

  3514                                      flags | MAP_FIXED,

  3515                                      -1, 0);

  3516       trcVerbose("SafePoint Polling  Page address: %p (wish) => %p",

  3517                    address_wishes[i], map_address + (ssize_t)page_size);

  3518 

  3519       if (map_address + (ssize_t)page_size == address_wishes[i]) {

  3520         // Map succeeded and map_address is at wished address, exit loop.

  3521         break;

  3522       }

  3523 

  3524       if (map_address != (address) MAP_FAILED) {

  3525         // Map succeeded, but polling_page is not at wished address, unmap and continue.

  3526         ::munmap(map_address, map_size);

  3527         map_address = (address) MAP_FAILED;

  3528       }

  3529       // Map failed, continue loop.

  3530     }

  3531   } // end OptimizePollingPageLocation

  3532 

  3533   if (map_address == (address) MAP_FAILED) {

  3534     map_address = (address) ::mmap(NULL, map_size, prot, flags, -1, 0);

  3535   }

  3536   guarantee(map_address != MAP_FAILED, "os::init_2: failed to allocate polling page");

  3537   os::set_polling_page(map_address);

  3538 

  3539   if (!UseMembar) {

  3540     address mem_serialize_page = (address) ::mmap(NULL, Aix::page_size(), PROT_READ | PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);

  3541     guarantee(mem_serialize_page != NULL, "mmap Failed for memory serialize page");

  3542     os::set_memory_serialize_page(mem_serialize_page);

  3543 

  3544     trcVerbose("Memory Serialize  Page address: %p - %p, size %IX (%IB)",

  3545         mem_serialize_page, mem_serialize_page + Aix::page_size(),

  3546         Aix::page_size(), Aix::page_size());

  3547   }

  3548