Changes between Version 2 and Version 3 of txt_device_api

Timestamp:

Jan 22, 2020, 12:10:40 AM (4 years ago)

Author:

alain

Comment:

--

txt_device_api

@@ -11 +11 @@
 The "user" API, contains the functions used  the user-level system calls, and by the kernel itself. It defines three operation types :  '''TXT_READ''', '''TXT_WRITE''', and '''TXT_SYNC_WRITE'''. This API is detailed in section C below.
 
-* The '''asynchronous''' TXT_READ and TXT_WRITE operations are not directly executed by the client thread. The requests are registered in the waiting queue rooted in the TXT chdev descriptor. These requests are actually handled by a dedicated server thread running in the cluster containing the chdev descriptor, that call the ''txt_driver_cmd()'' function.
-A TXT_WRITE operation (TX direction) moves N characters from a kernel buffer to the TXT terminal. A TXT_READ operation moves one single character from the TXT terminal to a kernel buffer. 
+* The '''asynchronous''' TXT_READ and TXT_WRITE operations are not directly executed by the client thread. The requests are registered in the waiting queue rooted in the TXT chdev descriptor. These requests are actually handled by a dedicated server thread running in the cluster containing the chdev descriptor, that call the ''txt_driver_cmd()'' function. A TXT_WRITE operation (TX direction) moves N characters from a kernel buffer to the TXT terminal. A TXT_READ operation moves one single character from the TXT terminal to a kernel buffer. 
 
 * The '''synchronous''' SYNC_WRITE operation is used by the kernel to display debug messages on the TXT0. It does not use the waiting queue, and it does not use the server thread. The client thread calls directly the ''txt_driver_aux()'' function, without using the the txt_command_t structure to communicate with the driver.