OK, so in RTAI this code from src/shm.c:53
static inline void *_rt_shm_alloc(unsigned long name, int size, int suprt)
{
void *adr;
//suprt = USE_GFP_ATOMIC; // to force some testing
if (!(adr = rt_get_adr_cnt(name)) && size > 0 && suprt >= 0 &&
RT_SHM_OP_PERM()) {
size = ((size - 1) & PAGE_MASK) + PAGE_SIZE;
if (adr = (suprt ? rkmalloc(&size, SUPRT[suprt]) : rvmalloc(size))) {
if (!rt_register(name, adr, suprt ? -size : size, 0)) {
if (suprt) {
rkfree(adr, size);
} else {
rvfree(adr, size);
}
return 0;
}
memset(ALIGN2PAGE(adr), 0, size);
}
}
rt_printk("adr = %lx , ALIGN2PAGE(adr) = %lx\n", adr, ALIGN2PAGE(adr));
return ALIGN2PAGE(adr);
}
Prints:
[58253.421443] *adr = ffffc90000409000 , ALIGN2PAGE(adr) = ffffc90000409000*
And this, from LinuxCNC src/rtapi/rtapi_ulapi.c:101
int rtapi_init(const char *modname)
{
int n, module_id;
module_data *module;
/* say hello */
rtapi_print_msg(RTAPI_MSG_INFO, "RTAPI: initing module %s\n", modname);
/* get shared memory block from OS and save its address */
errno = 0;
if(!rtapi_data){
rtapi_print("!rtapi_data, initing\n");
//rtapi_data = rtai_malloc(RTAPI_KEY, sizeof(rtapi_data_t));
rtapi_data = (rtapi_data_t*)rt_shm_alloc(RTAPI_KEY,
sizeof(rtapi_data_t), USE_GFP_ATOMIC);
rtapi_print("rtapi_data = %p\n", rtapi_data);
}
if (rtapi_data == NULL || rtapi_data == MAP_FAILED) {
rtapi_print_msg(RTAPI_MSG_ERR,
"RTAPI: ERROR: could not open shared memory (%s)\n",
(rtapi_data == MAP_FAILED ? "map failed" : strerror(errno)));
check_memlock_limit("could not open shared memory");
rtapi_data = 0;
return -ENOMEM;
}
nummods++;
prints:
!rtapi_data, initing
rtapi_data = 0xffffffffffffffff
RTAPI: ERROR: could not open shared memory (map failed)
HAL: ERROR: could not initialize RTAPI
So, somehow and somewhere the adr ( ffffc90000409000 ) is being returned to
rtapi_data as 0xffffffffffffffff
(the commented-out rtai_malloc is original LinuxCNC, I was trying to
takeout a layer of macros. Reverting that makes no difference, nor does
changing USE_GFP_ATOMIC to USE_VMALLOC which is the default)
https://www.rtai.org/userfiles/documentation/magma/html/api/group__shm.html#ga24
--
atp
"A motorcycle is a bicycle with a pandemonium attachment and is designed
for the especial use of mechanical geniuses, daredevils and lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912
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