Why does this hook function runs at boot time?

Hi,

I read hook function on TI wiki. I don't understand why it said:

 * This function is called at boot time.

Here is the link:

processors.wiki.ti.com/.../BIOS_FAQs

Could you explain it to me? Thanks,

Task.addHookSet({
    registerFxn: '&myRegisterFxn',
    createFxn: '&myCreateFxn',
    deleteFxn: '&myDeleteFxn',
    switchFxn: '&mySwitchFxn'
});
And these sample implementations to your .c file:

#include <xdc/std.h>
 
#include <xdc/runtime/Memory.h>
#include <xdc/runtime/Error.h>
#include <xdc/runtime/System.h>
 
#include <ti/sysbios/knl/Task.h>
 
/*
 * Task Hook Functions
 */
#define TLSSIZE 32
 
Int hookId;
 
/*
 * ======== myRegisterFxn ========
 * This function is called at boot time.
 */
Void myRegisterFxn(Int id)
{
     hookId = id;
}
 
/*
 * ======== myCreateFxn ========
 */
Void myCreateFxn(Task_Handle task, Error_Block *eb)
{
    Ptr tls;
     System_printf("myCreateFxn: task = 0x%x\n", task);
     Error_init(eb);
     tls = Memory_alloc(NULL, TLSSIZE, 0, eb);
 
     Task_setHookContext(task, hookId, tls);
}