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diff --git a/user/migration/v4_11-to-v5.rst b/user/migration/v4_11-to-v5.rst new file mode 100644 index 0000000..2dc97ec --- /dev/null +++ b/user/migration/v4_11-to-v5.rst @@ -0,0 +1,174 @@ +.. SPDX-License-Identifier: CC-BY-SA-4.0 + +.. Copyright (C) 2020 Chris Johns +.. Copyright (C) 2020 embedded brains GmbH & Co. KG + +.. _Migration_4_11_to_5: + +RTEMS 4.11 to RTEMS 5 +===================== + +This section provides helpful information when migrating from RTEMS 4.11 to +RTEMS 5. + +Application Configuration Options +--------------------------------- + +The evaluation of application configuration options in ``<rtems/confdefs.h>`` +was reworked during the RTEMS 5 development cycle. All options which let the +user define data structures were removed, this includes + +* ``CONFIGURE_HAS_OWN_CONFIGURATION_TABLE``, + +* ``CONFIGURE_HAS_OWN_BDBUF_TABLE``, + +* ``CONFIGURE_HAS_OWN_DEVICE_DRIVER_TABLE``, + +* ``CONFIGURE_HAS_OWN_FILESYSTEM_TABLE``, + +* ``CONFIGURE_HAS_OWN_INIT_TABLE``, + +* ``CONFIGURE_HAS_OWN_MOUNT_TABLE``, + +* ``CONFIGURE_HAS_OWN_MULTIPROCESSING_TABLE``, and + +* ``CONFIGURE_POSIX_HAS_OWN_INIT_THREAD_TABLE``. + +The configuration of SMP schedulers changed. For example, +:c:func:`RTEMS_SCHEDULER_EDF_SMP` has now only one parameter. Please read +section `Clustered Scheduler Configuration` in the `RTEMS Classic API Guide`. + +A number of configurations options have moved or are obsolete as a result of +internal changes in RTEMS. Some of these will produce a warning indicating the +new configuration settings you need to define. If you need to run an application +on RTEMS 4.11 and RTEMS 5 the following code example shows how to conditionally +define the settings. The example is: + +.. code-block:: c + + #include <rtems.h> + + #if __RTEMS_MAJOR__ < 5 + #define CONFIGURE_MAXIMUM_FIFOS 10 + #define CONFIGURE_MAXIMUM_PIPES 10 + #else + #define CONFIGURE_IMFS_ENABLE_MKFIFO + #endif + + #define MAX_FILE_DESCRIPTORS 200 + #if __RTEMS_MAJOR__ < 5 + #define CONFIGURE_LIBIO_MAXIMUM_FILE_DESCRIPTORS MAX_FILE_DESCRIPTORS + #else + #define CONFIGURE_MAXIMUM_FILE_DESCRIPTORS MAX_FILE_DESCRIPTORS + #endif + +Clock Manager +------------- + +The directive :c:func:`rtems_clock_get` was removed. See section +`Transition Advice for the Removed rtems_clock_get()` in the +`RTEMS Classic API Guide` for alternatives. + +File Descriptors +---------------- + +In RTEMS 5.1, the list of free file descriptors has a LIFO ordering in contrast +to previous versions where it was a FIFO. This means if an application +regularly opens and closes files (or sockets) it sees the whole range of file +descriptors. The reason for this change was to increase the time before file +descriptors are reused to more likely catch a file descriptor use after close. + +This change may surface application issues. If the configured file descriptor +maximum (``CONFIGURE_MAXIMUM_FILE_DESCRIPTORS``) is greater than the +``FD_SETSIZE`` defined by Newlib to 64, then calls to ``select()`` are undefined +behaviour and may corrupt the thread stack. In particular, ``FD_SET()`` may +result in an out of bounds access. It is possible to define a custom +``FD_SETSIZE``. The application must ensure that the custom ``FD_SETSIZE`` is +defined before ``<sys/select.h>`` is included in all modules used by the +application, for example via a global compiler command line define. This +applies also to all third-party libraries used by the application. + +Networking +---------- + +The following code samples provides a simple way to initialise and start +networking with the BSD Library's (``libbsd``) networking stack. The simplest +method to configure the networking stack is to provide a :file:`/etc/rc,conf` +file on your target. If your target has no non-volatile media for a file system +create the :file:`rc.conf` file each time your application starts. + +The :file:`rc.conf` support in ``libbsd`` provides a number of needed support +settings. We recommend you search for FreeBSD and ``rc.conf`` to view the +available online documentation that FreeBSD provides. + +In this example the network interface is ``cgem0``, replace with your +interface name. + +.. code-block:: c + + static const char* rc_conf = + "# /etc/rc.conf\n" \ + "hostname=\"rtems5-libbsd\"\n" \ + "ifconfig_cgem0=\"inet 10.1.2.3 netmask 255.255.255.0 rxcsum txcsum\"\n" \ + "ifconfig_cgem0_alias0=\"ether 00:80:81:82:83:84\"\n" \ + "defaultrouter=\"10.1.2.1\"\n" \ + "telnetd_enable=\"YES\"\n"; + + void start_network(void) + { + FILE *rc; + int r; + + /* + * Initialise libbsd. + */ + rtems_bsd_initialize(); + + /* + * Create the /etc/rc,conf, assume /etc exists. + */ + rc = fopen("/etc/rc.conf", "w"); + if (rc_conf == NULL) { + printf("error: cannot create /etc/rc.conf\n"); + exit(1); + } + + fprintf(rc, rc_conf); + fclose(rc); + + /* + * Arguments are timeout and trace + */ + r = rtems_bsd_run_etc_rc_conf(30, false); + if (r < 0) { + printf("error: loading /etc/rc.conf failed: %s\n",strerror(errno)); + exit(1); + } + } + +Shell Environment +----------------- + +To address resource leaks in the RTEMS shell, the management of shell +environments changed. This change may break existing code. Here is an example +how a broken Telnet shell can be fixed: + +.. code-block:: c + + static void + telnet_shell( char *name, void *arg ) + { + rtems_shell_env_t env; + + /* Previous WRONG approach: memset( &env, 0, sizeof( env) ); */ + + /* Correct way to initialize the shell environment */ + rtems_shell_dup_current_env( &env ); + + env.devname = name; + env.taskname = "TLNT"; + env.login_check = NULL; + env.forever = false; + + rtems_shell_main_loop( &env ); + } |