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8.2.1 Process Creation

atreset of processor in 2 computer system, an OS is initialized first, and then a process, which can be called initial
ess. is created (initialization of OS means enabling the use of OS functions, which includes the function to
create the processes). Then the OS is started and that runs an initial process (starting the OS means calling the OS
functions. which iis ए न 8 the created processes before the OS start but after the OS initialization)
Processes can be pase Berechically. The initial process creates Subsequent processes. OS schedules the processes

and provides for context switching between the processes and threads (Sections 7.1 to 7.3) processes

Example 8.2

(8) Recall Example 7.4. It showed an RTOS function to create a process Task_Send_Card_Info by using

OS_Task_Create ( ) function in the main. Task_Send_Card_Info task creates two other tasks,

‎and Task_Read_Port_Input. The OS then controls the context switching between‏ موی وو

‎(b) Consider ‏ونس‎ 7.2 for a mobile phone device (Section 1.10.5).

‎An OS function first creates the Display_process. The di i :
, Display _Time_DateThread ۳٣ھ‎ € display process then creates the following threads:

‎. Display_BatteryThread

‎. Display_SignalThread

‎, Display_ProfileThread

‎. Display_MessageThread

‎. Display_Call StatusThread

‎. Display_MenuThread.

‏ہم ‎(ಎ‏ انما ھ ہ) ‎ಧಾ‏ یہد

‎Creation of a process means specifying the resources for the process and address spaces (memory blocks)
for the created process, stack, data and heap, and placing the process initial information at ೩ PCB. The process
manager allocates a PCB (or TCB in case task represents a process) when it creates the process and later
manages it. The other OS units can send the manager the queries for the process when required. PCB is a

‎process descriptor used by the process manager.

‎A PCB or TCB (Sections 7.1 and 7.3) describes the following.
Context: Processor status word, PC, SP and other CPU registers at the instant of the last instruction

‎run executed when the process was left and the processor switched to another process.

‎2, Process stack pointer. ⋅ ടച്‌
3, Current state: Is it created, activated or spawned? Is it running: Is it blocked? (spawn means create

‎and activate) ١

‎4. Addresses that are allocated and that are presently in use.

‎5. Pointer for the parent process in case there exists a hierarchy of the processes.

‎6. Pointer to a list of daughter processes (processes lower in the hierarchy).

‎7. Pointer to a list of resources, which are usable (consumed) only once. For example, input data, memory
buffer or pipe, mailbox message, semaphore (there ര producers and consumers of these resources).

‎8. Pointer to a list of resource type usable more than कणर = resource ९८०३ example is a memory block.
Another example is an IO port. Each resource type ೫1 1 have a count of these types. For example, the
number of memory blocks or number of 10 ports.