1# Process 2 3## NAME 4 5process - Process abstraction 6 7## SYNOPSIS 8 9A zircon process is an instance of a program in the traditional 10sense: a set of instructions which will be executed by one or more 11threads, along with a collection of resources. 12 13## DESCRIPTION 14 15The process object is a container of the following resources: 16 17+ [Handles](../handles.md) 18+ [Virtual Memory Address Regions](vm_address_region.md) 19+ [Threads](thread.md) 20 21In general, it is associated with code which it is executing until it is 22forcefully terminated or the program exits. 23 24Processes are owned by [jobs](job.md) and allow an application that is 25composed by more than one process to be treated as a single entity, from the 26perspective of resource and permission limits, as well as lifetime control. 27 28### Lifetime 29A process is created via `zx_process_create()` and its execution begins with 30`zx_process_start()`. 31 32The process stops execution when: 33+ the last thread is terminated or exits 34+ the process calls ``zx_process_exit()`` 35+ the parent job terminates the process 36+ the parent job is destroyed 37 38The call to `zx_process_start()` cannot be issued twice. New threads cannot 39be added to a process that was started and then its last thread has exited. 40 41## SYSCALLS 42 43+ [process_create](../syscalls/process_create.md) - create a new process within a job 44+ [process_read_memory](../syscalls/process_read_memory.md) - read from a process's address space 45+ [process_start](../syscalls/process_start.md) - cause a new process to start executing 46+ [process_write_memory](../syscalls/process_write_memory.md) - write to a process's address space 47+ [process_exit](../syscalls/process_exit.md) - exit the current process 48 49<br> 50 51+ [job_create](../syscalls/job_create.md) - create a new job within a parent job 52 53<br> 54 55+ [vmar_map](../syscalls/vmar_map.md) - Map memory into an address space range 56+ [vmar_protect](../syscalls/vmar_protect.md) - Change permissions on an address space range 57+ [vmar_unmap](../syscalls/vmar_unmap.md) - Unmap memory from an address space range 58