source: rtems-libbsd/libbsd.txt @ c3a8e6b

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1RTEMS BSD Library Guide
2=======================
3:toc:
4:icons:
5:numbered:
6:website: http://www.rtems.org/
7
8RTEMS uses FreeBSD 9.2 as the source of its TCP/IP and USB stacks.
9This is a guide which captures information on the
10process of merging code from FreeBSD, building this library,
11RTEMS specific support files, and general guidelines on what
12modifications to the FreeBSD source are permitted.
13
14Goals of this effort are
15
16* update TCP/IP and provide USB in RTEMS,
17* ease updating to future FreeBSD versions,
18* ease tracking changes in FreeBSD code,
19* minimize manual changes in FreeBSD code, and
20* define stable kernel/device driver API which is implemented
21by both RTEMS and FreeBSD. This is the foundation of the port.
22
23We will work to push our changes upstream to the FreeBSD Project
24and minimize changes required at each update point.
25
26*******************************************************************************
27This is a work in progress and is very likely to be incomplete.
28Please help by adding to it.
29*******************************************************************************
30
31== Getting Started
32
33=== Tool Chain ===
34
35You need a tool chain for RTEMS based on at least
36
37* Binutils 2.24, and
38* Newlib 2.1.0.
39
40The Binutils version is required to ease the handling of linker command files.
41The Newlib version is required since some standard files like `<sys/types.h>`
42must be compatible enough for the files provided by the FreeBSD sources, e.g.
43`<sys/socket.h>`.
44
45=== Installation Overview ===
46
47. You must configure your BSP with the +--disable-networking+ option to disable
48the old network stack.  Make sure no header files of the old network stack are
49installed.
50. Clone the Git repository +git clone git://git.rtems.org/rtems-libbsd.git+.
51. Change into the RTEMS BSD library root directory.
52. Edit the `config.inc` Makefile configuration file and adjust it to your environment.
53. Run +make clean+.
54. Run +make install+.
55
56=== Board Support Package Requirements ===
57
58The RTEMS version must be at least 4.11.  The Board Support Package (BSP)
59should support the
60http://www.rtems.org/onlinedocs/doxygen/cpukit/html/group\__rtems\__interrupt__extension.html[Interrupt Manager Extension]
61// The first underscores have to be masked to stop asciidoc interpreting them
62to make use of generic FreeBSD based drivers.
63
64The linker command file of the BSP must contain the following section
65definitions:
66
67-------------------------------------------------------------------------------
68.rtemsroset : {
69        KEEP (*(SORT(.rtemsroset.*)))
70}
71
72.rtemsrwset : {
73        KEEP (*(SORT(.rtemsrwset.*)))
74}
75-------------------------------------------------------------------------------
76
77The first output section can be placed in read-only memory.  The second output
78section must be placed in read-write memory.  The output section name is not
79relevant.  The output sections may also contain other input sections.
80
81=== Board Support Package Configuration and Build ===
82
83You need to configure RTEMS for the desired BSP and install it.  The BSP should
84be configured with a disabled network stack.  The BSD library containing the
85new network stack is a separate package.  Using a BSP installation containing
86the old network stack may lead to confusion and unpredictable results.
87
88The following script is used to build the `arm/realview_pbx_a9_qemu` BSP for
89our internal testing purposes:
90
91-------------------------------------------------------------------------------
92#!/bin/sh
93
94cd ${HOME}/sandbox
95rm -rf b-realview_pbx_a9_qemu
96mkdir b-realview_pbx_a9_qemu
97cd b-realview_pbx_a9_qemu
98${HOME}/git-rtems/configure \
99        --prefix=${HOME}/sandbox/install \
100        --target=arm-rtems4.11 \
101        --enable-rtemsbsp=realview_pbx_a9_qemu \
102        --disable-networking && \
103        make && \
104        make install
105-------------------------------------------------------------------------------
106
107The `arm/realview_pbx_a9_qemu` BSP running on the Qemu simulator has some
108benefits for development and test of the BSD library
109
110* it offers a NULL pointer read and write protection,
111* Qemu is a fast simulator,
112* Qemu provides support for GDB watchpoints,
113* Qemu provides support for virtual Ethernet networks, e.g. TUN and bridge
114devices (you can run multiple test instances on one virtual network).
115
116=== BSD Library Configuration and Build ===
117
118There are currently 2 build systems supported. The first is based on the RTEMS
119Makefile support in RTEMS and installed with the BSP and the second is a stand
120alone environment based on the Waf build system. The Makefile build system will
121be removed when RTEMS moves away from its existing build system and Waf will
122be the preferred build environment.
123
124To build with Waf please refer to the README.waf file.
125
126===== Makefile Building =====
127
128In the BSD library source directory edit the file `config.inc`.  Continuing on
129the above, the `config.inc` used to match the above is:
130
131-------------------------------------------------------------------------------
132# Mandatory: Select your BSP and installation prefix
133TARGET = arm-rtems4.11
134BSP = realview_pbx_a9_qemu
135PREFIX = $(HOME)/sandbox/install
136
137# Optional: Separate installation base directory
138INSTALL_BASE = $(PREFIX)/$(TARGET)/$(BSP)
139
140# Optional: Network test configuration
141TEST_RUNNER = $(BSP)
142NET_CFG_SELF_IP = 10.0.0.2
143NET_CFG_NETMASK = 255.255.0.0
144NET_CFG_PEER_IP = 10.0.0.1
145NET_CFG_GATEWAY_IP = 10.0.0.1
146NET_TAP_INTERFACE = tap0
147-------------------------------------------------------------------------------
148
149Now you can build the BSD library and run the tests:
150
151-------------------------------------------------------------------------------
152make clean
153make
154make run_tests
155-------------------------------------------------------------------------------
156
157You can only run the tests directly in case a test runner is available.  The
158following tests run without an external network.  It is strongly advised to run
159them.
160
161* commands01
162* init01
163* loopback01
164* rwlock01
165* selectpollkqueue01
166* sleep01
167* swi01
168* syscalls01
169* thread01
170* timeout01
171* unix01
172
173To install the BSD library use this:
174
175-------------------------------------------------------------------------------
176make install
177-------------------------------------------------------------------------------
178
179=== BSD Library Initialization ===
180
181Use the following code to initialize the BSD library:
182
183-------------------------------------------------------------------------------
184#include <assert.h>
185#include <sysexits.h>
186
187#include <machine/rtems-bsd-commands.h>
188#include <rtems/bsd/bsd.h>
189
190static void
191network_ifconfig_lo0(void)
192{
193        int exit_code;
194        char *lo0[] = {
195                "ifconfig",
196                "lo0",
197                "inet",
198                "127.0.0.1",
199                "netmask",
200                "255.255.255.0",
201                NULL
202        };
203        char *lo0_inet6[] = {
204                "ifconfig",
205                "lo0",
206                "inet6",
207                "::1",
208                "prefixlen",
209                "128",
210                NULL
211        };
212
213        exit_code = rtems_bsd_command_ifconfig(RTEMS_BSD_ARGC(lo0), lo0);
214        assert(exit_code == EX_OK);
215
216        exit_code = rtems_bsd_command_ifconfig(RTEMS_BSD_ARGC(lo0_inet6), lo0_inet6);
217        assert(exit_code == EX_OK);
218}
219
220void
221network_init(void)
222{
223        rtems_status_code sc;
224
225        sc = rtems_bsd_initialize();
226        assert(sc == RTEMS_SUCCESSFUL);
227
228        network_ifconfig_lo0();
229}
230-------------------------------------------------------------------------------
231
232This performs the basic network stack initialization with a loopback interface.
233Further initialization must be done using the standard BSD network
234configuration commands
235http://www.freebsd.org/cgi/man.cgi?query=ifconfig&apropos=0&sektion=8&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[IFCONFIG(8)]
236using `rtems_bsd_command_ifconfig()` and
237http://www.freebsd.org/cgi/man.cgi?query=route&apropos=0&sektion=8&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[ROUTE(8)]
238using `rtems_bsd_command_route()`.  For an example please have a look at
239`testsuite/include/rtems/bsd/test/default-network-init.h`.
240
241=== Task Priorities and Stack Size ===
242
243The default task priority is 96 for the interrupt server task (name "IRQS"), 98
244for the timer server task (name "TIME") and 100 for all other tasks.  The
245application may provide their own implementation of the
246`rtems_bsd_get_task_priority()` function (for example in the module which calls
247`rtems_bsd_initialize()`) if different values are desired.
248
249The task stack size is determined by the `rtems_bsd_get_task_stack_size()`
250function which may be provided by the application in case the default is not
251appropriate.
252
253=== Size for Allocator Domains ===
254
255The size for an allocator domain can be specified via the
256`rtems_bsd_get_allocator_domain_size()` function.  The application may provide
257their own implementation of the `rtems_bsd_get_allocator_domain_size()`
258function (for example in the module which calls `rtems_bsd_initialize()`) if
259different values are desired.  The default size is 8MiB for all domains.
260
261== Network Stack Features
262
263http://roy.marples.name/projects/dhcpcd/index[DHCPCD(8)]:: DHCP client
264
265https://developer.apple.com/library/mac/documentation/Networking/Reference/DNSServiceDiscovery_CRef/Reference/reference.html[dns_sd.h]:: DNS Service Discovery
266
267http://www.opensource.apple.com/source/mDNSResponder/mDNSResponder-320.10/mDNSCore/mDNSEmbeddedAPI.h[mDNS]:: Multi-Cast DNS
268
269http://www.freebsd.org/cgi/man.cgi?query=unix&sektion=4&apropos=0&manpath=FreeBSD+9.2-RELEASE[UNIX(4)]:: UNIX-domain protocol family
270
271http://www.freebsd.org/cgi/man.cgi?query=inet&sektion=4&apropos=0&manpath=FreeBSD+9.2-RELEASE[INET(4)]:: Internet protocol family
272
273http://www.freebsd.org/cgi/man.cgi?query=inet6&apropos=0&sektion=4&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[INET6(4)]:: Internet protocol version 6 family
274
275http://www.freebsd.org/cgi/man.cgi?query=tcp&apropos=0&sektion=4&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[TCP(4)]:: Internet Transmission Control Protocol
276
277http://www.freebsd.org/cgi/man.cgi?query=udp&apropos=0&sektion=4&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[UDP(4)]:: Internet User Datagram Protocol
278
279http://www.freebsd.org/cgi/man.cgi?query=route&sektion=4&apropos=0&manpath=FreeBSD+9.2-RELEASE[ROUTE(4)]:: Kernel packet forwarding database
280
281http://www.freebsd.org/cgi/man.cgi?query=bpf&apropos=0&sektion=4&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[BPF(4)]:: Berkeley Packet Filter
282
283http://www.freebsd.org/cgi/man.cgi?query=socket&apropos=0&sektion=2&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[SOCKET(2)]:: Create an endpoint for communication
284
285http://www.freebsd.org/cgi/man.cgi?query=kqueue&apropos=0&sektion=2&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[KQUEUE(2)]:: Kernel event notification mechanism
286
287http://www.freebsd.org/cgi/man.cgi?query=select&apropos=0&sektion=2&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[SELECT(2)]:: Synchronous I/O multiplexing
288
289http://www.freebsd.org/cgi/man.cgi?query=poll&apropos=0&sektion=2&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[POLL(2)]:: Synchronous I/O multiplexing
290
291http://www.freebsd.org/cgi/man.cgi?query=route&apropos=0&sektion=8&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[ROUTE(8)]:: Manually manipulate the routing tables
292
293http://www.freebsd.org/cgi/man.cgi?query=ifconfig&apropos=0&sektion=8&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[IFCONFIG(8)]:: Configure network interface parameters
294
295http://www.freebsd.org/cgi/man.cgi?query=netstat&apropos=0&sektion=1&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[NETSTAT(1)]:: Show network status
296
297http://www.freebsd.org/cgi/man.cgi?query=ping&apropos=0&sektion=8&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[PING(8)]:: Send ICMP ECHO_REQUEST packets to network hosts
298
299http://www.freebsd.org/cgi/man.cgi?query=ping6&apropos=0&sektion=8&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[PING6(8)]:: Send ICMPv6 ECHO_REQUEST packets to network hosts
300
301http://www.freebsd.org/cgi/man.cgi?query=sysctl&sektion=3&apropos=0&manpath=FreeBSD+9.2-RELEASE[SYSCTL(3)]:: Get or set system information
302
303http://www.freebsd.org/cgi/man.cgi?query=resolver&sektion=3&apropos=0&manpath=FreeBSD+9.2-RELEASE[RESOLVER(3)]:: Resolver routines
304
305http://www.freebsd.org/cgi/man.cgi?query=gethostbyname&sektion=3&apropos=0&manpath=FreeBSD+9.2-RELEASE[GETHOSTBYNAME(3)]:: Get network host entry
306
307== Network Interface Drivers
308
309=== Link Up/Down Events
310
311You can notifiy the application space of link up/down events in your network
312interface driver via the if_link_state_change(LINK_STATE_UP/LINK_STATE_DOWN)
313function.  The DHCPCD(8) client is a consumer of these events for example.
314Make sure that the interface flag IFF_UP and the interface driver flag
315IFF_DRV_RUNNING is set in case the link is up, otherwise ether_output() will
316return the error status ENETDOWN.
317
318== Shell Commands
319
320=== HOSTNAME(1)
321
322In addition to the standard options the RTEMS version of the HOSTNAME(1)
323command supports the -m flag to set/get the multicast hostname of the
324mDNS resolver instance.  See also rtems_mdns_sethostname() and
325rtems_mdns_gethostname().
326
327== Issues and TODO
328
329* Priority queues are broken with clustered scheduling.
330
331* Per-CPU data should be enabled once the new stack is ready for SMP.
332
333* Per-CPU NETISR(9) should be enabled onece the new stack is ready for SMP.
334
335* Multiple routing tables are not supported.  Every FIB value is set to zero
336  (= BSD_DEFAULT_FIB).
337
338* Process identifiers are not supported.  Every PID value is set to zero
339  (= BSD_DEFAULT_PID).
340
341* User credentials are not supported.  The following functions allow the
342  operation for everyone
343  - prison_equal_ip4(),
344  - chgsbsize(),
345  - cr_cansee(),
346  - cr_canseesocket() and
347  - cr_canseeinpcb().
348
349* A basic USB functionality test that is known to work on Qemu is desirable.
350
351* Adapt generic IRQ PIC interface code to Simple Vectored Interrupt Model
352  so that those architectures can use new TCP/IP and USB code.
353
354* freebsd-userspace/rtems/include/sys/syslog.h is a copy from the old
355  RTEMS TCP/IP stack. For some reason, the __printflike markers do not
356  compile in this environment. We may want to use the FreeBSD syslog.h
357  and get this addressed.
358
359* in_cksum implementations for architectures not supported by FreeBSD.
360  This will require figuring out where to put implementations that do
361  not originate from FreeBSD and are populated via the script.
362
363* MAC support functions are not thread-safe ("freebsd/lib/libc/posix1e/mac.c").
364
365* IFCONFIG(8): IEEE80211 support is disabled.  This module depends on a XML
366  parser and mmap().
367
368* get_cyclecount(): The implementation is a security problem.
369
370* What to do with the priority parameter present in the FreeBSD synchronization
371  primitives and the thread creation functions?
372
373* TASKQUEUE(9): Support spin mutexes.
374
375* ZONE(9): Review allocator lock usage in rtems-bsd-chunk.c.
376
377* KQUEUE(2): Choose proper lock for global kqueue list.
378
379* TIMEOUT(9): Maybe use special task instead of timer server to call
380  callout_tick().
381
382* sysctl_handle_opaque(): Implement reliable snapshots.
383
384* PING6(8): What to do with SIGALARM?
385
386* <sys/param.h>: Update Newlib to use a MSIZE of 256.
387
388* BPF(4): Add support for zero-copy buffers.
389
390* UNIX(4): Fix race conditions in the area of socket object and file node
391  destruction.  Add support for file descriptor transmission via control
392  messages.
393
394* PRINTF(9): Add support for log(), the %D format specifier is missing in the
395  normal printf() family.
396
397* Why is the interrupt server used?  The BSD interrupt handlers can block on
398synchronization primitives like mutexes.  This is in contrast to RTEMS
399interrupt service routines.  The BSPs using the generic interrupt support must
400implement the `bsp_interrupt_vector_enable()` and
401`bsp_interrupt_vector_disable()` routines.  They normally enable/disable a
402particular interrupt source at the interrupt controller.  This can be used to
403implement the interrupt server.  The interrupt server is a task that wakes-up
404in case an associated interrupt happens.  The interrupt source is disabled in
405a generic interrupt handler that wakes-up the interrupt server task.   Once the
406postponed interrupt processing is performed in the interrupt server the
407interrupt source is enabled again.
408
409* Convert all BSP linkcmds to use a linkcmds.base so the sections are
410easier to insert.
411
412* NIC Device Drivers
413- Only common PCI NIC drivers have been included in the initial set. These
414do not include any system on chip or ISA drivers.
415- PCI configuration probe does not appear to happen to determine if a
416NIC is in I/O or memory space. We have worked around this by using a
417static hint to tell the fxp driver the correct mode. But this needs to
418be addressed.
419- The ISA drivers require more BSD infrastructure to be addressed. This was
420outside the scope of the initial porting effort.
421
422== FreeBSD Source
423
424You should be able to rely on FreebSD manual pages and documentation
425for details on the code itself.
426
427=== Automatically Generated FreeBSD Files
428
429Some source and header files are automatically generated during the FreeBSD
430build process.  The `Makefile.todo` file performs this manually.  The should be
431included in `freebsd-to-rtems.py` script some time in the future.  For details,
432see also
433http://www.freebsd.org/cgi/man.cgi?query=kobj&sektion=9&apropos=0&manpath=FreeBSD+9.2-RELEASE[KOBJ(9)].
434
435=== Rules for Modifying FreeBSD Source
436
437Only add lines.  If your patch contains lines starting with a '-', then this is
438wrong.  Subtract code by added `#ifndef __rtems__`.  This makes merging easier
439in the future.  For example:
440
441-------------------------------------------------------------------------------
442/* Global variables for the kernel. */
443
444#ifndef __rtems__
445/* 1.1 */
446extern char kernelname[MAXPATHLEN];
447#endif /* __rtems__ */
448
449extern int tick;                        /* usec per tick (1000000 / hz) */
450-------------------------------------------------------------------------------
451
452-------------------------------------------------------------------------------
453#if defined(_KERNEL) || defined(_WANT_FILE)
454#ifdef __rtems__
455#include <rtems/libio_.h>
456#include <sys/fcntl.h>
457#endif /* __rtems__ */
458/*
459 * Kernel descriptor table.
460 * One entry for each open kernel vnode and socket.
461 *
462 * Below is the list of locks that protects members in struct file.
463 *
464 * (f) protected with mtx_lock(mtx_pool_find(fp))
465 * (d) cdevpriv_mtx
466 * none not locked
467 */
468-------------------------------------------------------------------------------
469
470-------------------------------------------------------------------------------
471extern int profprocs;                   /* number of process's profiling */
472#ifndef __rtems__
473extern volatile int ticks;
474#else /* __rtems__ */
475#include <rtems/score/watchdogimpl.h>
476#define ticks _Watchdog_Ticks_since_boot
477#endif /* __rtems__ */
478
479#endif /* _KERNEL */
480-------------------------------------------------------------------------------
481
482Add nothing (even blank lines) before or after the `__rtems__` guards.  Always
483include a `__rtems__` in the guards to make searches easy, so use
484
485* `#ifndef __rtems__`,
486* `#ifdef __rtems__`,
487* `#else /* __rtems__ */`, and
488* `#endif /* __rtems__ */`.
489
490For new code use
491http://www.freebsd.org/cgi/man.cgi?query=style&apropos=0&sektion=9&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[STYLE(9)].
492Do not format original FreeBSD code.
493
494== BSD Library Source
495
496=== What is in the Git Repository
497
498There is a self-contained kit with FreeBSD and RTEMS components pre-merged. The
499Makefile in this kit is automatically generated.
500
501Any changes to source in the `freebsd` directories will need to be merged
502upstream into our master FreeBSD checkout, the `freebsd-org` submodule.
503
504The repository contains two FreeBSD source trees.  In the `freebsd` directory
505are the so called 'managed' FreeBSD sources used to build the BSD library.  The
506FreeBSD source in `freebsd-org` is the 'master' version.  The
507`freebsd-to-rtems.py` script is used to transfer files between the two trees.
508In general terms, if you have modified managed FreeBSD sources, you will need
509to run the script in 'revert' or 'reverse' mode using the `-R` switch.  This
510will copy the source back to your local copy of the master FreeBSD source so
511you can run `git diff` against the upstream FreeBSD source.  If you want to
512transfer source files from the master FreeBSD source to the manged FreeBSD
513sources, then you must run the script in 'forward' mode (the default).
514
515=== Organization
516
517The top level directory contains a few directories and files. The following
518are important to understand
519
520* `freebsd-to-rtems.py` - script to convert to and free FreeBSD and RTEMS trees,
521* `Makefile` - automatically generated,
522* `freebsd/` - from FreeBSD by script,
523* `rtemsbsd/` - RTEMS specific implementations of FreeBSD kernel support routines,
524* `testsuite/` - RTEMS specific tests, and
525* `libbsd.txt` - documentation in Asciidoc.
526
527== Moving Code Between Managed and Master FreeBSD Source
528
529The script `freebsd-to-rtems.py` is used to copy code from FreeBSD to the
530rtems-libbsd tree and to reverse this process. This script attempts to
531automate this process as much as possible and performs some transformations
532on the FreeBSD code. Its command line arguments are shown below:
533
534----
535freebsd-to-rtems.py [args]
536  -?|-h|--help     print this and exit
537  -d|--dry-run     run program but no modifications
538  -D|--diff        provide diff of files between trees
539  -e|--early-exit  evaluate arguments, print results, and exit
540  -m|--makefile    just generate Makefile
541  -R|--reverse     default FreeBSD -> RTEMS, reverse that
542  -r|--rtems       RTEMS directory
543  -f|--freebsd     FreeBSD directory
544  -v|--verbose     enable verbose output mode
545----
546
547In its default mode of operation, freebsd-to-rtems.py is used to copy code
548from FreeBSD to the rtems-libbsd tree and perform transformations.  In forward
549mode, the script may be requested to just generate the Makefile and Waf script.
550
551In "reverse mode", this script undoes those transformations and copies
552the source code back to the FreeBSD SVN tree. This allows us to do
553'svn diff', evaluate changes made by the RTEMS Project, and report changes
554back to FreeBSD upstream.
555
556In either mode, the script may be asked to perform a dry-run or be verbose.
557Also, in either mode, the script is also smart enough to avoid copying over
558files which have not changed. This means that the timestamps of files are
559not changed unless the contents change. The script will also report the
560number of files which changed. In verbose mode, the script will print
561the name of the files which are changed.
562
563The following is an example forward run with no changes.
564
565----
566$ ~/newbsd/git/libbsd-8.2/freebsd-to-rtems.py \
567    -r /home/joel/newbsd/git/libbsd-8.2 \
568    -f /home/joel/newbsd/libbsd/freebsd-8.2 -v
569Verbose:                yes
570Dry Run:                no
571Only Generate Makefile: no
572RTEMS Directory:        /home/joel/newbsd/git/libbsd-8.2
573FreeBSD Directory:      /home/joel/newbsd/libbsd/freebsd-8.2
574Direction:              forward
575Generating into /home/joel/newbsd/git/libbsd-8.2
5760 files were changed.
577----
578
579The script may also be used to generate a diff in either forward or reverse
580direction.
581
582== Porting of user space utilities
583
584The theory behind the described method is to put all BSS and initialized data
585objects into a named section. This section then will be saved before the code is
586executed and restored after it has finished. This method limits to a single
587threaded execution of the application but minimizes the necessary changes to the
588original FreeBSD code.
589
590. Import and commit the unchanged source files like described above.
591. Add the files to the libbsd.py and build them.
592. Use nm on the generated object files to find out which objects are initialized
593  (either in BSS -- type b or B -- or in the initialized data segment -- type d
594  or D). An example call could look like follows:
595  `arm-rtems4.12-nm build/arm-rtems4.12-xilinx_zynq_a9_qemu/freebsd/contrib/pf/pfctl/pfctl.c.10.o | grep ' [DdbB] '`
596. Check the sources for everything that can be made const. This type of patches
597  should go back to the upstream FreeBSD sources.
598. Check the sources for every global variable that can be made static. This type
599  of patches should go back to the upstream FreeBSD sources.
600. Move static variables out of functions. This patches should also go upstream.
601. Create one `xxx-data.h` file per c module. This header should contain
602  declarations for the remaining initialized objects matching the original
603  declarations but adding a section attribute. The section name has to match the
604  name of the RTEMS_LINKER_RWSET defined further below. For an example look at
605  `freebsd/contrib/pf/pfctl/pfctl-data.h`.
606. Include the header files at the end of the corresponding c files.
607. Add a rtems_bsd_command_xxx wrapper function to the c file containing the main
608  function. For an example look at `rtems_bsd_command_pfctl(...)` in
609  `freebsd/contrib/pf/pfctl/pfctl.c`.
610. Create one compilable commit.
611
612== Initialization of the BSD Library
613
614The initialization of the BSD library is based on the FreeBSD SYSINIT(9)
615infrastructure.  The key to initializing a system is to ensure that the desired
616device drivers are explicitly pulled into the linked application.  This plus
617linking against the BSD library (`libbsd.a`) will pull in the necessary FreeBSD
618infrastructure.
619
620The FreeBSD kernel is not a library like the RTEMS kernel.  It is a bunch of
621object files linked together.  If we have a library, then creating the
622executable is simple.  We begin with a start symbol and recursively resolve all
623references.  With a bunch of object files linked together we need a different
624mechanism.  Most object files don't know each other.  Lets say we have a driver
625module.  The rest of the system has no references to this driver module.  The
626driver module needs a way to tell the rest of the system: Hey, kernel I am
627here, please use my services!
628
629This registration of independent components is performed by SYSINIT(9) and
630specializations:
631
632http://www.freebsd.org/cgi/man.cgi?query=SYSINIT
633
634The SYSINIT(9) uses some global data structures that are placed in a certain
635section.  In the linker command file we need this:
636
637-------------------------------------------------------------------------------
638.rtemsroset : {
639        KEEP (*(SORT(.rtemsroset.*)))
640}
641
642.rtemsrwset : {
643        KEEP (*(SORT(.rtemsrwset.*)))
644}
645-------------------------------------------------------------------------------
646
647This results for example in this executable layout:
648
649-------------------------------------------------------------------------------
650[...]
651 *(SORT(.rtemsroset.*))
652 .rtemsroset.bsd.modmetadata_set.begin
653                0x000000000025fe00        0x0 libbsd.a(rtems-bsd-init.o)
654                0x000000000025fe00                _bsd__start_set_modmetadata_set
655 .rtemsroset.bsd.modmetadata_set.content
656                0x000000000025fe00        0x8 libbsd.a(rtems-bsd-nexus.o)
657 .rtemsroset.bsd.modmetadata_set.content
658                0x000000000025fe08        0x4 libbsd.a(kern_module.o)
659[...]
660 .rtemsroset.bsd.modmetadata_set.content
661                0x000000000025fe68        0x4 libbsd.a(mii.o)
662 .rtemsroset.bsd.modmetadata_set.content
663                0x000000000025fe6c        0x4 libbsd.a(mii_bitbang.o)
664 .rtemsroset.bsd.modmetadata_set.end
665                0x000000000025fe70        0x0 libbsd.a(rtems-bsd-init.o)
666                0x000000000025fe70                _bsd__stop_set_modmetadata_set
667[...]
668.rtemsrwset     0x000000000030bad0      0x290
669 *(SORT(.rtemsrwset.*))
670 .rtemsrwset.bsd.sysinit_set.begin
671                0x000000000030bad0        0x0 libbsd.a(rtems-bsd-init.o)
672                0x000000000030bad0                _bsd__start_set_sysinit_set
673 .rtemsrwset.bsd.sysinit_set.content
674                0x000000000030bad0        0x4 libbsd.a(rtems-bsd-nexus.o)
675 .rtemsrwset.bsd.sysinit_set.content
676                0x000000000030bad4        0x8 libbsd.a(rtems-bsd-thread.o)
677 .rtemsrwset.bsd.sysinit_set.content
678                0x000000000030badc        0x4 libbsd.a(init_main.o)
679[...]
680 .rtemsrwset.bsd.sysinit_set.content
681                0x000000000030bd54        0x4 libbsd.a(frag6.o)
682 .rtemsrwset.bsd.sysinit_set.content
683                0x000000000030bd58        0x8 libbsd.a(uipc_accf.o)
684 .rtemsrwset.bsd.sysinit_set.end
685                0x000000000030bd60        0x0 libbsd.a(rtems-bsd-init.o)
686                0x000000000030bd60                _bsd__stop_set_sysinit_set
687[...]
688-------------------------------------------------------------------------------
689
690Here you can see, that some global data structures are collected into
691continuous memory areas.  This memory area can be identified by start and stop
692symbols.  This constructs a table of uniform items.
693
694The low level FreeBSD code calls at some time during the initialization the
695mi_startup() function (machine independent startup).  This function will sort
696the SYSINIT(9) set and call handler functions which perform further
697initialization.  The last step is the scheduler invocation.
698
699The SYSINIT(9) routines are run in mi_startup() which is called by
700rtems_bsd_initialize().
701
702This is also explained in "The Design and Implementation of the FreeBSD
703Operating System" section 14.3 "Kernel Initialization".
704
705In RTEMS we have a library and not a bunch of object files.  Thus we need a way
706to pull-in the desired services out of the libbsd.  Here the
707`rtems-bsd-sysinit.h` comes into play.  The SYSINIT(9) macros have been
708modified and extended for RTEMS in `<sys/kernel.h>`:
709
710-------------------------------------------------------------------------------
711#ifndef __rtems__
712#define C_SYSINIT(uniquifier, subsystem, order, func, ident)    \
713        static struct sysinit uniquifier ## _sys_init = {       \
714                subsystem,                                      \
715                order,                                          \
716                func,                                           \
717                (ident)                                         \
718        };                                                      \
719        DATA_SET(sysinit_set,uniquifier ## _sys_init)
720#else /* __rtems__ */
721#define SYSINIT_ENTRY_NAME(uniquifier)                          \
722        _bsd_ ## uniquifier ## _sys_init
723#define SYSINIT_REFERENCE_NAME(uniquifier)                      \
724        _bsd_ ## uniquifier ## _sys_init_ref
725#define C_SYSINIT(uniquifier, subsystem, order, func, ident)    \
726        struct sysinit SYSINIT_ENTRY_NAME(uniquifier) = {       \
727                subsystem,                                      \
728                order,                                          \
729                func,                                           \
730                (ident)                                         \
731        };                                                      \
732        RWDATA_SET(sysinit_set,SYSINIT_ENTRY_NAME(uniquifier))
733#define SYSINIT_REFERENCE(uniquifier)                           \
734        extern struct sysinit SYSINIT_ENTRY_NAME(uniquifier);   \
735        static struct sysinit const * const                     \
736        SYSINIT_REFERENCE_NAME(uniquifier) __used               \
737        = &SYSINIT_ENTRY_NAME(uniquifier)
738#define SYSINIT_MODULE_REFERENCE(mod)                           \
739        SYSINIT_REFERENCE(mod ## module)
740#define SYSINIT_DRIVER_REFERENCE(driver, bus)                   \
741        SYSINIT_MODULE_REFERENCE(driver ## _ ## bus)
742#define SYSINIT_DOMAIN_REFERENCE(dom)                           \
743        SYSINIT_REFERENCE(domain_add_ ## dom)
744#endif /* __rtems__ */
745-------------------------------------------------------------------------------
746
747Here you see that the SYSINIT(9) entries are no longer static.  The
748\*_REFERENCE() macros will create references to the corresponding modules which
749are later resolved by the linker.  The application has to provide an object
750file with references to all required FreeBSD modules.
751
752The FreeBSD device model is quite elaborated (with follow-ups):
753
754http://www.freebsd.org/cgi/man.cgi?query=driver
755
756The devices form a tree with the Nexus device at a high-level.  This Nexus
757device is architecture specific in FreeBSD.  In RTEMS we have our own Nexus
758device, see `rtemsbsd/bsp/bsp-bsd-nexus-devices.c`.
759
760=== SYSCTL_NODE Example
761
762During development, we had an undefined reference to
763_bsd_sysctl__net_children that we had trouble tracking down. Thanks to
764Chris Johns, we located it. He explained how to read SYSCTL_NODE
765definitions. This line from freebsd/netinet/in_proto.c is attempting
766to add the "inet" node to the parent node "_net".
767
768----
769SYSCTL_NODE(_net,      PF_INET,         inet,   CTLFLAG_RW, 0,
770        "Internet Family");
771----
772
773Our problem was that we could not find where _bsd_sysctl__net_children
774was defined. Chris suggested that when in doubt compile with -save-temps
775and look at the preprocessed .i files. But he did not need that. He
776explained that this the symbol name _bsd_sysctl__net_children was
777automatically generated by a SYSCTL_NODE as follows:
778
779* _bsd_ - added by RTEMS modifications to SYSCTL_NODE macro
780* sysctl_ - boilerplace added by SYSCTL_NODE macro
781* "" - empty string for parent node
782* net - name of SYSCTL_NODE
783* children - added by SYSCTL macros
784
785This was all generated by a support macro declaring the node as this:
786
787----
788struct sysctl_oid_list SYSCTL_NODE_CHILDREN(parent, name);
789----
790
791Given this information, we located this SYSCTL_NODE declaration in
792kern/kern_mib.c
793
794----
795SYSCTL_NODE(, CTL_KERN,   kern,   CTLFLAG_RW, 0,
796        "High kernel, proc, limits &c");
797----
798
799== Core FreeBSD APIs and RTEMS Replacements ==
800
801=== SX(9) (Shared/exclusive locks) ===
802
803http://www.freebsd.org/cgi/man.cgi?query=sx
804
805Binary semaphores (this neglects the ability to allow shared access).
806
807=== MUTEX(9) (Mutual exclusion) ===
808
809http://www.freebsd.org/cgi/man.cgi?query=mutex
810
811Binary semaphores (not recursive mutexes are not supported this way).
812
813=== RWLOCK(9) (Reader/writer lock) ===
814
815http://www.freebsd.org/cgi/man.cgi?query=rwlock
816
817POSIX r/w lock.
818
819=== RMLOCK(9) (Reader/writer lock optimized for mostly read access patterns) ===
820
821Note:  This object was implemented as a wrapper for RWLOCK in the rm_lock header file.
822
823http://www.freebsd.org/cgi/man.cgi?query=rmlock
824
825POSIX r/w lock.
826
827=== CONDVAR(9) (Condition variables) ===
828
829http://www.freebsd.org/cgi/man.cgi?query=condvar
830
831POSIX condition variables with modifications (hack).
832
833=== CALLOUT(9) (Timer functions) ===
834
835http://www.freebsd.org/cgi/man.cgi?query=callout
836
837Timer server.
838
839=== TASKQUEUE(9) (Asynchronous task execution) ===
840
841http://www.freebsd.org/cgi/man.cgi?query=taskqueue
842
843TBD.
844
845=== KTHREAD(9), KPROC(9) (Tasks) ===
846
847http://www.freebsd.org/cgi/man.cgi?query=kthread
848
849http://www.freebsd.org/cgi/man.cgi?query=kproc
850
851Tasks.
852
853=== ZONE(9) (Zone allocator) ===
854
855http://www.freebsd.org/cgi/man.cgi?query=zone
856
857TBD.
858
859=== devfs (Device file system) ===
860
861Dummy, IMFS or new implementation (currently dummy).
862
863=== psignal (Signals) ===
864
865TBD.  Seems to be not needed.
866
867=== poll, select ===
868
869TBD.  Seems to be not needed.
870
871=== RMAN(9) (Resource management) ===
872
873http://www.freebsd.org/cgi/man.cgi?query=rman
874
875TBD.  Seems to be not needed.
876
877=== DEVCLASS(9), DEVICE(9), DRIVER(9), MAKE_DEV(9) (Device management) ===
878
879http://www.freebsd.org/cgi/man.cgi?query=devclass
880
881http://www.freebsd.org/cgi/man.cgi?query=device
882
883http://www.freebsd.org/cgi/man.cgi?query=driver
884
885http://www.freebsd.org/cgi/man.cgi?query=make_dev
886
887Use FreeBSD implementation as far as possible.  FreeBSD has a nice API for
888dynamic device handling.  It may be interesting for RTEMS to use this API
889internally in the future.
890
891=== BUS_SPACE(9), BUS_DMA(9) (Bus and DMA access) ===
892
893http://www.freebsd.org/cgi/man.cgi?query=bus_space
894
895http://www.freebsd.org/cgi/man.cgi?query=bus_dma
896
897Likely BSP dependent.  A default implementation for memory mapped linear access
898is easy to provide.  The current heap implementation supports all properties
899demanded by bus_dma (including the boundary constraint).
900
901== RTEMS Replacements by File Description ==
902
903Note:  Files with a status of USB are used by the USB test and have at least
904been partially tested.  If they contain both USB and Nic, then they are used
905by both and MAY contain methods that have not been tested yet.  Files that
906are only used by the Nic test are the most suspect.
907
908----
909rtems-libbsd File:      rtems-bsd-assert.c
910FreeBSD File:           rtems-bsd-config.h redefines BSD_ASSERT.
911Description:            This file contains the support method rtems_bsd_assert_func().
912Status:                 USB, Nic
913
914rtems-libbsd File:      rtems-bsd-autoconf.c
915FreeBSD File:           FreeBSD has BSP specific autoconf.c
916Description:            This file contains configuration methods that are used to setup the system.
917Status:                 USB
918
919rtems-libbsd File:      rtems-bsd-bus-dma.c
920FreeBSD File:           FreeBSD has BSP specific busdma_machdep.c
921Description:
922Status:                 USB, Nic
923
924rtems-libbsd File:      rtems-bsd-bus-dma-mbuf.c
925FreeBSD File:           FreeBSD has BSP specific busdma_machdep.c
926Description:
927Status:                 Nic
928
929rtems-libbsd File:      rtems-bsd-callout.c
930FreeBSD File:           kern/kern_timeout.c
931Description:
932Status:                 USB, Nic
933
934rtems-libbsd File:      rtems-bsd-cam.c
935FreeBSD File:           cam/cam_sim.c
936Description:
937Status:                 USB
938
939rtems-libbsd File:      rtems-bsd-condvar.c
940FreeBSD File:           kern/kern_condvar.c
941Description:
942Status:                 USB
943
944rtems-libbsd File:      rtems-bsd-copyinout.c
945FreeBSD File:           bsp specific copyinout.c )
946Description:            Note: The FreeBSD file is split with some methods being in rtems-bsd-support
947Status:                 Nic
948
949rtems-libbsd File:      rtems-bsd-delay.c
950FreeBSD File:           bsp specific file with multiple names
951Description:
952Status:                 USB, Nic
953
954rtems-libbsd File:      rtems-bsd-descrip.c
955FreeBSD File:           kern/kern_descrip.c
956Description:
957Status:                 Nic
958
959rtems-libbsd File:      rtems-bsd-generic.c
960FreeBSD File:           kern/sys_generic.c
961Description:
962Status:                 Nic
963
964rtems-libbsd File:      rtems-bsd-init.c
965FreeBSD File:           N/A
966Description:
967Status:                 USB, Nic
968
969rtems-libbsd File:      rtems-bsd-init-with-irq.c
970FreeBSD File:           N/A
971Description:
972Status:                 USB, Nic
973
974rtems-libbsd File:      rtems-bsd-jail.c
975FreeBSD File:           kern/kern_jail.c
976Description:
977Status:                 USB, Nic
978
979rtems-libbsd File:      rtems-bsd-lock.c
980FreeBSD File:           kern/subr_lock.c
981Description:
982Status:                 USB, Nic
983
984rtems-libbsd File:      rtems-bsd-log.c
985FreeBSD File:           kern/subr_prf.c
986Description:
987Status:                 Nic
988
989rtems-libbsd File:      rtems-bsd-malloc.c
990FreeBSD File:           kern/kern_malloc.c
991Description:
992Status:                 USB, Nic
993
994rtems-libbsd File:      rtems-bsd-mutex.c
995FreeBSD File:           kern/kern_mutex.c
996Description:
997Status:                 USB, Nic
998
999rtems-libbsd File:      rtems-bsd-newproc.c
1000FreeBSD File:           N/A
1001Description:
1002Status:                 Nic
1003
1004rtems-libbsd File:      rtems-bsd-nexus.c
1005FreeBSD File:           bsp specific nexus.c
1006Description:
1007Status:                 USB
1008
1009rtems-libbsd File:      rtems-bsd-panic.c
1010FreeBSD File:           boot/common/panic.c
1011Description:
1012Status:                 USB, Nic
1013
1014rtems-libbsd File:      rtems-bsd-rwlock.c
1015FreeBSD File:           kern_rwlock.c
1016Description:
1017Status:                 USB, Nic
1018
1019rtems-libbsd File:      rtems-bsd-shell.c
1020FreeBSD File:           N/A
1021Description:
1022Status:                 USB
1023
1024rtems-libbsd File:      rtems-bsd-signal.c
1025FreeBSD File:           kern/kern_sig.c
1026Description:
1027Status:                 Nic
1028
1029rtems-libbsd File:      rtems-bsd-smp.c
1030FreeBSD File:           N/A
1031Description:
1032Status:                 Nic
1033
1034rtems-libbsd File:      rtems-bsd-support.c
1035FreeBSD File:           bsp specific copyinout.c
1036Description:            Note: the FreeBSD file is split with some methods being in rtems-bsd-copyinout.
1037Status:                 USB, Nic
1038
1039rtems-libbsd File:      rtems-bsd-sx.c
1040FreeBSD File:           kern/kern_sx.c
1041Description:            Status: USB, Nic
1042
1043rtems-libbsd File:      rtems-bsd-synch.c
1044FreeBSD File:           kern/kern_synch.c
1045Description:
1046Status:                 USB, Nic
1047
1048rtems-libbsd File:      rtems-bsd-syscalls.c
1049FreeBSD File:           User API for kern/uipc_syscalls.c
1050Description:
1051Status:                 Nic
1052
1053rtems-libbsd File:      rtems-bsd-sysctlbyname.c
1054FreeBSD File:           User API for sysctlbyname(3)
1055Description:
1056Status:
1057
1058rtems-libbsd File:      rtems-bsd-sysctl.c
1059FreeBSD File:           User API for sysctl(8)
1060Description:
1061Status:
1062
1063rtems-libbsd File:      rtems-bsd-sysctlnametomib.c
1064FreeBSD File:           User API for sysctlnametomib
1065Description:
1066Status:
1067
1068rtems-libbsd File:      rtems-bsd-taskqueue.c
1069FreeBSD File:           kern/subr_taskqueue.c
1070Description:
1071Status:                 Nic
1072
1073rtems-libbsd File:      rtems-bsd-thread.c
1074FreeBSD File:           kern/kern_kthread.c
1075Description:
1076Status:                 USB, Nic
1077
1078rtems-libbsd File:      rtems-bsd-timeout.c
1079FreeBSD File:           kern/kern_timeout.c
1080Description:
1081Status:                 Nic
1082
1083rtems-libbsd File:      rtems-bsd-timesupport.c
1084FreeBSD File:           kern/kern_clock.c
1085Description:
1086Status:                 Nic
1087
1088rtems-libbsd File:      rtems-bsd-vm_glue.c
1089FreeBSD File:           vm/vm_glue.c
1090Description:
1091Status:                 USB, Nic
1092----
1093
1094== Notes by File ==
1095
1096altq_subr.c - Arbitrary choices were made in this file that RTEMS would
1097not support tsc frequency change.  Additionally, the clock frequency
1098for machclk_freq is always measured for RTEMS.
1099
1100conf.h - In order to add make_dev and destroy_dev, variables in the cdev
1101structure that were not being used were conditionally compiled out. The
1102capability of supporting children did not appear to be needed and was
1103not implemented in the rtems version of these routines.
1104
1105== NICs Status ==
1106
1107----
1108Driver                  Symbol                          Status
1109======                  ======                          ======
1110RealTek                 _bsd_re_pcimodule_sys_init      Links
1111EtherExpress            _bsd_fxp_pcimodule_sys_init     Links
1112DEC tulip               _bsd_dc_pcimodule_sys_init      Links
1113Broadcom BCM57xxx       _bsd_bce_pcimodule_sys_init     Links
1114Broadcom BCM4401        _bsd_bfe_pcimodule_sys_init     Links
1115Broadcom BCM570x        _bsd_bge_pcimodule_sys_init     Needs Symbols (A)
1116E1000 IGB               _bsd_igb_pcimodule_sys_init     Links
1117E1000 EM                _bsd_em_pcimodule_sys_init      Links
1118Cadence                 ?                               Links, works.
1119----
1120
1121Symbols (A)
1122         pci_get_vpd_ident
1123
1124=== Cadence ===
1125
1126The cadence driver works on the Xilinx Zynq platform. The hardware checksum
1127support works on real hardware but does not seem to be supported on qemu
1128therefore the default state is to disable TXCSUM and RXCSUM and this can be
1129enabled from the shell with:
1130
1131  # ifconfig cgem0 rxcsum txcsum
1132
1133or with an ioctl call to the network interface driver with SIOCSIFCAP and the
1134mask IFCAP_TXCSUM and IFCAP_RXCSUM set.
1135
1136== Problems to report to FreeBSD ==
1137
1138The MMAP_NOT_AVAILABLE define is inverted on its usage.  When it is
1139defined the mmap method is called. Additionally, it is not used
1140thoroughly. It is not used in the unmap portion of the source.
1141The file rec_open.c uses the define MMAP_NOT_AVAILABLE to wrap
1142the call to mmap and file rec_close.c uses the munmap method.
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