Changes between Version 61 and Version 62 of io_operations

Timestamp:

Jan 22, 2020, 4:35:21 PM (4 years ago)

Author:

alain

Comment:

--

io_operations

@@ -144 +144 @@
 '''2)''' The other (NB_TXT_CHANNELS - 1) terminals TXT[i] are used by user processes. The first INIT user process,  creates  (NB_TXT_CHANNELS -1) KSH user processes (one shell per user text terminal). All processes created by a KSH[i] process share the same TXT[i] terminal as the parent process, and belong to the same group of process. 
 
-'''3)''' In the present implementation, the INIT process and the the KSH[i] processes are never deleted : they do not call the exit() syscall, and cannot be killed.
+'''3)''' The INIT process is never deleted : it does not call the exit() syscall, and cannot be killed. The the KSH[i] processes should not be deleted : the KSH main thread does not call the exit() sys call. But the KSH process can be killed, and is - in principle - automatically recreated by the parent INIT process, when it is killed.
 
-'''4)''' Regarding the WRITE accesses, all processes attached to the same TXT_TX[i] terminal can atomically display character strings. There is no guaranty on the order, when these strings are issued by different processes, because these strings are simply sequentialized by the kernel thread associated to the shared TXT_TX[i] device.
+'''4)''' Regarding the WRITE accesses, all processes attached to the same TXT_TX[i] terminal can atomically display character strings. There is no guaranty on the order, when these strings are issued by different processes, because these strings are simply sequentialized by the server thread associated to the shared TXT_TX[i] device.
 
 '''5)''' Regarding the READ accesses, only one process in the group of process attached to the TXT[i] terminal (called  ''foreground'' process) is the owner of the TXT_RX[i] terminal, and can read characters . The other processes (called ''background'' processes) should not try to read characters. If a background process P try to read, it receives a SIGSTOP signal, and will keep blocked until the user uses the ''fg'' shell command to give P the ownership of the TXT_RX[i] terminal.