source: rtems-libbsd/libbsd.txt @ 8475e7a

4.115-freebsd-12freebsd-9.3
Last change on this file since 8475e7a was 8475e7a, checked in by Sebastian Huber <sebastian.huber@…>, on Mar 24, 2015 at 9:02:45 AM

SLEEPQUEUE(9): Port to RTEMS

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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
118In the BSD library source directory edit the file `config.inc`.  Continuing on
119the above, the `config.inc` used to match the above is:
120
121-------------------------------------------------------------------------------
122# Mandatory: Select your BSP and installation prefix
123TARGET = arm-rtems4.11
124BSP = realview_pbx_a9_qemu
125PREFIX = $(HOME)/sandbox/install
126
127# Optional: Separate installation base directory
128INSTALL_BASE = $(PREFIX)/$(TARGET)/$(BSP)
129
130# Optional: Network test configuration
131TEST_RUNNER = $(BSP)
132NET_CFG_SELF_IP = 10.0.0.2
133NET_CFG_NETMASK = 255.255.0.0
134NET_CFG_PEER_IP = 10.0.0.1
135NET_CFG_GATEWAY_IP = 10.0.0.1
136NET_TAP_INTERFACE = tap0
137-------------------------------------------------------------------------------
138
139Now you can build the BSD library and run the tests:
140
141-------------------------------------------------------------------------------
142make clean
143make
144make run_tests
145-------------------------------------------------------------------------------
146
147You can only run the tests directly in case a test runner is available.  The
148following tests run without an external network.  It is strongly advised to run
149them.
150
151* commands01
152* init01
153* loopback01
154* rwlock01
155* selectpollkqueue01
156* sleep01
157* swi01
158* syscalls01
159* thread01
160* timeout01
161* unix01
162
163To install the BSD library use this:
164
165-------------------------------------------------------------------------------
166make install
167-------------------------------------------------------------------------------
168
169=== BSD Library Initialization ===
170
171Use the following code to initialize the BSD library:
172
173-------------------------------------------------------------------------------
174#include <assert.h>
175#include <sysexits.h>
176
177#include <machine/rtems-bsd-commands.h>
178#include <rtems/bsd/bsd.h>
179
180static void
181network_ifconfig_lo0(void)
182{
183        int exit_code;
184        char *lo0[] = {
185                "ifconfig",
186                "lo0",
187                "inet",
188                "127.0.0.1",
189                "netmask",
190                "255.255.255.0",
191                NULL
192        };
193        char *lo0_inet6[] = {
194                "ifconfig",
195                "lo0",
196                "inet6",
197                "::1",
198                "prefixlen",
199                "128",
200                NULL
201        };
202
203        exit_code = rtems_bsd_command_ifconfig(RTEMS_BSD_ARGC(lo0), lo0);
204        assert(exit_code == EX_OK);
205
206        exit_code = rtems_bsd_command_ifconfig(RTEMS_BSD_ARGC(lo0_inet6), lo0_inet6);
207        assert(exit_code == EX_OK);
208}
209
210void
211network_init(void)
212{
213        rtems_status_code sc;
214
215        sc = rtems_bsd_initialize();
216        assert(sc == RTEMS_SUCCESSFUL);
217
218        network_ifconfig_lo0();
219}
220-------------------------------------------------------------------------------
221
222This performs the basic network stack initialization with a loopback interface.
223Further initialization must be done using the standard BSD network
224configuration commands
225http://www.freebsd.org/cgi/man.cgi?query=ifconfig&apropos=0&sektion=8&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[IFCONFIG(8)]
226using `rtems_bsd_command_ifconfig()` and
227http://www.freebsd.org/cgi/man.cgi?query=route&apropos=0&sektion=8&manpath=FreeBSD+9.2-RELEASE&arch=default&format=html[ROUTE(8)]
228using `rtems_bsd_command_route()`.  For an example please have a look at
229`testsuite/include/rtems/bsd/test/default-network-init.h`.
230
231=== Task Priorities and Stack Size ===
232
233The default task priority is 96 for the interrupt server task (name "IRQS"), 98
234for the timer server task (name "TIME") and 100 for all other tasks.  The
235application may provide their own implementation of the
236`rtems_bsd_get_task_priority()` function (for example in the module which calls
237`rtems_bsd_initialize()`) if different values are desired.
238
239The task stack size is determined by the `rtems_bsd_get_task_stack_size()`
240function which may be provided by the application in case the default is not
241appropriate.
242
243=== Size for Allocator Domains ===
244
245The size for an allocator domain can be specified via the
246`rtems_bsd_get_allocator_domain_size()` function.  The application may provide
247their own implementation of the `rtems_bsd_get_allocator_domain_size()`
248function (for example in the module which calls `rtems_bsd_initialize()`) if
249different values are desired.  The default size is 8MiB for all domains.
250
251== Network Stack Features
252
253http://roy.marples.name/projects/dhcpcd/index[DHCPCD(8)]:: DHCP client
254
255https://developer.apple.com/library/mac/documentation/Networking/Reference/DNSServiceDiscovery_CRef/Reference/reference.html[dns_sd.h]:: DNS Service Discovery
256
257http://www.opensource.apple.com/source/mDNSResponder/mDNSResponder-320.10/mDNSCore/mDNSEmbeddedAPI.h[mDNS]:: Multi-Cast DNS
258
259http://www.freebsd.org/cgi/man.cgi?query=unix&sektion=4&apropos=0&manpath=FreeBSD+9.2-RELEASE[UNIX(4)]:: UNIX-domain protocol family
260
261http://www.freebsd.org/cgi/man.cgi?query=inet&sektion=4&apropos=0&manpath=FreeBSD+9.2-RELEASE[INET(4)]:: Internet protocol family
262
263http://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
264
265http://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
266
267http://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
268
269http://www.freebsd.org/cgi/man.cgi?query=route&sektion=4&apropos=0&manpath=FreeBSD+9.2-RELEASE[ROUTE(4)]:: Kernel packet forwarding database
270
271http://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
272
273http://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
274
275http://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
276
277http://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
278
279http://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
280
281http://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
282
283http://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
284
285http://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
286
287http://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
288
289http://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
290
291http://www.freebsd.org/cgi/man.cgi?query=sysctl&sektion=3&apropos=0&manpath=FreeBSD+9.2-RELEASE[SYSCTL(3)]:: Get or set system information
292
293http://www.freebsd.org/cgi/man.cgi?query=resolver&sektion=3&apropos=0&manpath=FreeBSD+9.2-RELEASE[RESOLVER(3)]:: Resolver routines
294
295http://www.freebsd.org/cgi/man.cgi?query=gethostbyname&sektion=3&apropos=0&manpath=FreeBSD+9.2-RELEASE[GETHOSTBYNAME(3)]:: Get network host entry
296
297== Network Interface Drivers
298
299=== Link Up/Down Events
300
301You can notifiy the application space of link up/down events in your network
302interface driver via the if_link_state_change(LINK_STATE_UP/LINK_STATE_DOWN)
303function.  The DHCPCD(8) client is a consumer of these events for example.
304Make sure that the interface flag IFF_UP and the interface driver flag
305IFF_DRV_RUNNING is set in case the link is up, otherwise ether_output() will
306return the error status ENETDOWN.
307
308== Shell Commands
309
310=== HOSTNAME(1)
311
312In addition to the standard options the RTEMS version of the HOSTNAME(1)
313command supports the -m flag to set/get the multicast hostname of the
314mDNS resolver instance.  See also rtems_mdns_sethostname() and
315rtems_mdns_gethostname().
316
317== Issues and TODO
318
319* Priority queues are broken with clustered scheduling.
320
321* Per-CPU data should be enabled once the new stack is ready for SMP.
322
323* Per-CPU NETISR(9) should be enabled onece the new stack is ready for SMP.
324
325* Multiple routing tables are not supported.  Every FIB value is set to zero
326  (= BSD_DEFAULT_FIB).
327
328* Process identifiers are not supported.  Every PID value is set to zero
329  (= BSD_DEFAULT_PID).
330
331* User credentials are not supported.  The following functions allow the
332  operation for everyone
333  - prison_equal_ip4(),
334  - chgsbsize(),
335  - cr_cansee(),
336  - cr_canseesocket() and
337  - cr_canseeinpcb().
338
339* A basic USB functionality test that is known to work on Qemu is desirable.
340
341* Adapt generic IRQ PIC interface code to Simple Vectored Interrupt Model
342  so that those architectures can use new TCP/IP and USB code.
343
344* freebsd-userspace/rtems/include/sys/syslog.h is a copy from the old
345  RTEMS TCP/IP stack. For some reason, the __printflike markers do not
346  compile in this environment. We may want to use the FreeBSD syslog.h
347  and get this addressed.
348
349* in_cksum implementations for architectures not supported by FreeBSD.
350  This will require figuring out where to put implementations that do
351  not originate from FreeBSD and are populated via the script.
352
353* MAC support functions are not thread-safe ("freebsd/lib/libc/posix1e/mac.c").
354
355* IFCONFIG(8): IEEE80211 support is disabled.  This module depends on a XML
356  parser and mmap().
357
358* get_cyclecount(): The implementation is a security problem.
359
360* What to do with the priority parameter present in the FreeBSD synchronization
361  primitives and the thread creation functions?
362
363* TASKQUEUE(9): Support spin mutexes.
364
365* ZONE(9): Review allocator lock usage in rtems-bsd-chunk.c.
366
367* KQUEUE(2): Choose proper lock for global kqueue list.
368
369* TIMEOUT(9): Maybe use special task instead of timer server to call
370  callout_tick().
371
372* sysctl_handle_opaque(): Implement reliable snapshots.
373
374* PING6(8): What to do with SIGALARM?
375
376* <sys/param.h>: Update Newlib to use a MSIZE of 256.
377
378* BPF(4): Add support for zero-copy buffers.
379
380* UNIX(4): Fix race conditions in the area of socket object and file node
381  destruction.  Add support for file descriptor transmission via control
382  messages.
383
384* PRINTF(9): Add support for log(), the %D format specifier is missing in the
385  normal printf() family.
386
387* Why is the interrupt server used?  The BSD interrupt handlers can block on
388synchronization primitives like mutexes.  This is in contrast to RTEMS
389interrupt service routines.  The BSPs using the generic interrupt support must
390implement the `bsp_interrupt_vector_enable()` and
391`bsp_interrupt_vector_disable()` routines.  They normally enable/disable a
392particular interrupt source at the interrupt controller.  This can be used to
393implement the interrupt server.  The interrupt server is a task that wakes-up
394in case an associated interrupt happens.  The interrupt source is disabled in
395a generic interrupt handler that wakes-up the interrupt server task.   Once the
396postponed interrupt processing is performed in the interrupt server the
397interrupt source is enabled again.
398
399* Convert all BSP linkcmds to use a linkcmds.base so the sections are
400easier to insert.
401
402* NIC Device Drivers
403- Only common PCI NIC drivers have been included in the initial set. These
404do not include any system on chip or ISA drivers.
405- PCI configuration probe does not appear to happen to determine if a
406NIC is in I/O or memory space. We have worked around this by using a
407static hint to tell the fxp driver the correct mode. But this needs to
408be addressed.
409- The ISA drivers require more BSD infrastructure to be addressed. This was
410outside the scope of the initial porting effort.
411
412== FreeBSD Source
413
414You should be able to rely on FreebSD manual pages and documentation
415for details on the code itself.
416
417=== Automatically Generated FreeBSD Files
418
419Some source and header files are automatically generated during the FreeBSD
420build process.  The `Makefile.todo` file performs this manually.  The should be
421included in `freebsd-to-rtems.py` script some time in the future.  For details,
422see also
423http://www.freebsd.org/cgi/man.cgi?query=kobj&sektion=9&apropos=0&manpath=FreeBSD+9.2-RELEASE[KOBJ(9)].
424
425=== Rules for Modifying FreeBSD Source
426
427Only add lines.  Subtract code by added `#ifndef __rtems__`.  This makes
428merging easier in the future.  For example:
429
430-------------------------------------------------------------------------------
431/* Global variables for the kernel. */
432
433#ifndef __rtems__
434/* 1.1 */
435extern char kernelname[MAXPATHLEN];
436#endif /* __rtems__ */
437
438extern int tick;                        /* usec per tick (1000000 / hz) */
439-------------------------------------------------------------------------------
440
441-------------------------------------------------------------------------------
442#if defined(_KERNEL) || defined(_WANT_FILE)
443#ifdef __rtems__
444#include <rtems/libio_.h>
445#include <sys/fcntl.h>
446#endif /* __rtems__ */
447/*
448 * Kernel descriptor table.
449 * One entry for each open kernel vnode and socket.
450 *
451 * Below is the list of locks that protects members in struct file.
452 *
453 * (f) protected with mtx_lock(mtx_pool_find(fp))
454 * (d) cdevpriv_mtx
455 * none not locked
456 */
457-------------------------------------------------------------------------------
458
459-------------------------------------------------------------------------------
460extern int profprocs;                   /* number of process's profiling */
461#ifndef __rtems__
462extern volatile int ticks;
463#else /* __rtems__ */
464#include <rtems/score/watchdogimpl.h>
465#define ticks _Watchdog_Ticks_since_boot
466#endif /* __rtems__ */
467
468#endif /* _KERNEL */
469-------------------------------------------------------------------------------
470
471Add nothing (even blank lines) before or after the `__rtems__` guards.  Always
472include a `__rtems__` in the guards to make searches easy.
473
474== BSD Library Source
475
476=== What is in the Git Repository
477
478There is a self-contained kit with FreeBSD and RTEMS components pre-merged. The
479Makefile in this kit is automatically generated.
480
481Any changes to source in the `freebsd` directories will need to be merged
482upstream into our master FreeBSD checkout, the `freebsd-org` submodule.
483
484The repository contains two FreeBSD source trees.  In the `freebsd` directory
485are the so called 'managed' FreeBSD sources used to build the BSD library.  The
486FreeBSD source in `freebsd-org` is the 'master' version.  The
487`freebsd-to-rtems.py` script is used to transfer files between the two trees.
488In general terms, if you have modified managed FreeBSD sources, you will need
489to run the script in 'revert' or 'reverse' mode using the `-R` switch.  This
490will copy the source back to your local copy of the master FreeBSD source so
491you can run `git diff` against the upstream FreeBSD source.  If you want to
492transfer source files from the master FreeBSD source to the manged FreeBSD
493sources, then you must run the script in 'forward' mode (the default).
494
495=== Organization
496
497The top level directory contains a few directories and files. The following
498are important to understand
499
500* `freebsd-to-rtems.py` - script to convert to and free FreeBSD and RTEMS trees,
501* `Makefile` - automatically generated,
502* `freebsd/` - from FreeBSD by script,
503* `rtemsbsd/` - RTEMS specific implementations of FreeBSD kernel support routines,
504* `testsuite/` - RTEMS specific tests, and
505* `libbsd.txt` - documentation in Asciidoc.
506
507== Moving Code Between Managed and Master FreeBSD Source
508
509The script `freebsd-to-rtems.py` is used to copy code from FreeBSD to the
510rtems-libbsd tree and to reverse this process. This script attempts to
511automate this process as much as possible and performs some transformations
512on the FreeBSD code. Its command line arguments are shown below:
513
514----
515freebsd-to-rtems.py [args]
516  -?|-h|--help     print this and exit
517  -d|--dry-run     run program but no modifications
518  -D|--diff        provide diff of files between trees
519  -e|--early-exit  evaluate arguments, print results, and exit
520  -m|--makefile    just generate Makefile
521  -R|--reverse     default FreeBSD -> RTEMS, reverse that
522  -r|--rtems       RTEMS directory
523  -f|--freebsd     FreeBSD directory
524  -v|--verbose     enable verbose output mode
525----
526
527In its default mode of operation, freebsd-to-rtems.py is used to copy code
528from FreeBSD to the rtems-libbsd tree and perform transformations.  In forward
529mode, the script may be requested to just generate the Makefile.
530
531In "reverse mode", this script undoes those transformations and copies
532the source code back to the FreeBSD SVN tree. This allows us to do
533'svn diff', evaluate changes made by the RTEMS Project, and report changes
534back to FreeBSD upstream.
535
536In either mode, the script may be asked to perform a dry-run or be verbose.
537Also, in either mode, the script is also smart enough to avoid copying over
538files which have not changed. This means that the timestamps of files are
539not changed unless the contents change. The script will also report the
540number of files which changed. In verbose mode, the script will print
541the name of the files which are changed.
542
543The following is an example forward run with no changes.
544
545----
546$ ~/newbsd/git/libbsd-8.2/freebsd-to-rtems.py \
547    -r /home/joel/newbsd/git/libbsd-8.2 \
548    -f /home/joel/newbsd/libbsd/freebsd-8.2 -v
549Verbose:                yes
550Dry Run:                no
551Only Generate Makefile: no
552RTEMS Directory:        /home/joel/newbsd/git/libbsd-8.2
553FreeBSD Directory:      /home/joel/newbsd/libbsd/freebsd-8.2
554Direction:              forward
555Generating into /home/joel/newbsd/git/libbsd-8.2
5560 files were changed.
557----
558
559The script may also be used to generate a diff in either forward or reverse
560direction.
561
562== Initialization of the BSD Library
563
564The initialization of the BSD library is based on the FreeBSD SYSINIT(9)
565infrastructure.  The key to initializing a system is to ensure that the desired
566device drivers are explicitly pulled into the linked application.  This plus
567linking against the BSD library (`libbsd.a`) will pull in the necessary FreeBSD
568infrastructure.
569
570The FreeBSD kernel is not a library like the RTEMS kernel.  It is a bunch of
571object files linked together.  If we have a library, then creating the
572executable is simple.  We begin with a start symbol and recursively resolve all
573references.  With a bunch of object files linked together we need a different
574mechanism.  Most object files don't know each other.  Lets say we have a driver
575module.  The rest of the system has no references to this driver module.  The
576driver module needs a way to tell the rest of the system: Hey, kernel I am
577here, please use my services!
578
579This registration of independent components is performed by SYSINIT(9) and
580specializations:
581
582http://www.freebsd.org/cgi/man.cgi?query=SYSINIT
583
584The SYSINIT(9) uses some global data structures that are placed in a certain
585section.  In the linker command file we need this:
586
587-------------------------------------------------------------------------------
588.rtemsroset : {
589        KEEP (*(SORT(.rtemsroset.*)))
590}
591
592.rtemsrwset : {
593        KEEP (*(SORT(.rtemsrwset.*)))
594}
595-------------------------------------------------------------------------------
596
597This results for example in this executable layout:
598
599-------------------------------------------------------------------------------
600[...]
601 *(SORT(.rtemsroset.*))
602 .rtemsroset.bsd.modmetadata_set.begin
603                0x000000000025fe00        0x0 libbsd.a(rtems-bsd-init.o)
604                0x000000000025fe00                _bsd__start_set_modmetadata_set
605 .rtemsroset.bsd.modmetadata_set.content
606                0x000000000025fe00        0x8 libbsd.a(rtems-bsd-nexus.o)
607 .rtemsroset.bsd.modmetadata_set.content
608                0x000000000025fe08        0x4 libbsd.a(kern_module.o)
609[...]
610 .rtemsroset.bsd.modmetadata_set.content
611                0x000000000025fe68        0x4 libbsd.a(mii.o)
612 .rtemsroset.bsd.modmetadata_set.content
613                0x000000000025fe6c        0x4 libbsd.a(mii_bitbang.o)
614 .rtemsroset.bsd.modmetadata_set.end
615                0x000000000025fe70        0x0 libbsd.a(rtems-bsd-init.o)
616                0x000000000025fe70                _bsd__stop_set_modmetadata_set
617[...]
618.rtemsrwset     0x000000000030bad0      0x290
619 *(SORT(.rtemsrwset.*))
620 .rtemsrwset.bsd.sysinit_set.begin
621                0x000000000030bad0        0x0 libbsd.a(rtems-bsd-init.o)
622                0x000000000030bad0                _bsd__start_set_sysinit_set
623 .rtemsrwset.bsd.sysinit_set.content
624                0x000000000030bad0        0x4 libbsd.a(rtems-bsd-nexus.o)
625 .rtemsrwset.bsd.sysinit_set.content
626                0x000000000030bad4        0x8 libbsd.a(rtems-bsd-thread.o)
627 .rtemsrwset.bsd.sysinit_set.content
628                0x000000000030badc        0x4 libbsd.a(init_main.o)
629[...]
630 .rtemsrwset.bsd.sysinit_set.content
631                0x000000000030bd54        0x4 libbsd.a(frag6.o)
632 .rtemsrwset.bsd.sysinit_set.content
633                0x000000000030bd58        0x8 libbsd.a(uipc_accf.o)
634 .rtemsrwset.bsd.sysinit_set.end
635                0x000000000030bd60        0x0 libbsd.a(rtems-bsd-init.o)
636                0x000000000030bd60                _bsd__stop_set_sysinit_set
637[...]
638-------------------------------------------------------------------------------
639
640Here you can see, that some global data structures are collected into
641continuous memory areas.  This memory area can be identified by start and stop
642symbols.  This constructs a table of uniform items.
643
644The low level FreeBSD code calls at some time during the initialization the
645mi_startup() function (machine independent startup).  This function will sort
646the SYSINIT(9) set and call handler functions which perform further
647initialization.  The last step is the scheduler invocation.
648
649The SYSINIT(9) routines are run in mi_startup() which is called by
650rtems_bsd_initialize().
651
652This is also explained in "The Design and Implementation of the FreeBSD
653Operating System" section 14.3 "Kernel Initialization".
654
655In RTEMS we have a library and not a bunch of object files.  Thus we need a way
656to pull-in the desired services out of the libbsd.  Here the
657`rtems-bsd-sysinit.h` comes into play.  The SYSINIT(9) macros have been
658modified and extended for RTEMS in `<sys/kernel.h>`:
659
660-------------------------------------------------------------------------------
661#ifndef __rtems__
662#define C_SYSINIT(uniquifier, subsystem, order, func, ident)    \
663        static struct sysinit uniquifier ## _sys_init = {       \
664                subsystem,                                      \
665                order,                                          \
666                func,                                           \
667                (ident)                                         \
668        };                                                      \
669        DATA_SET(sysinit_set,uniquifier ## _sys_init)
670#else /* __rtems__ */
671#define SYSINIT_ENTRY_NAME(uniquifier)                          \
672        _bsd_ ## uniquifier ## _sys_init
673#define SYSINIT_REFERENCE_NAME(uniquifier)                      \
674        _bsd_ ## uniquifier ## _sys_init_ref
675#define C_SYSINIT(uniquifier, subsystem, order, func, ident)    \
676        struct sysinit SYSINIT_ENTRY_NAME(uniquifier) = {       \
677                subsystem,                                      \
678                order,                                          \
679                func,                                           \
680                (ident)                                         \
681        };                                                      \
682        RWDATA_SET(sysinit_set,SYSINIT_ENTRY_NAME(uniquifier))
683#define SYSINIT_REFERENCE(uniquifier)                           \
684        extern struct sysinit SYSINIT_ENTRY_NAME(uniquifier);   \
685        static struct sysinit const * const                     \
686        SYSINIT_REFERENCE_NAME(uniquifier) __used               \
687        = &SYSINIT_ENTRY_NAME(uniquifier)
688#define SYSINIT_MODULE_REFERENCE(mod)                           \
689        SYSINIT_REFERENCE(mod ## module)
690#define SYSINIT_DRIVER_REFERENCE(driver, bus)                   \
691        SYSINIT_MODULE_REFERENCE(driver ## _ ## bus)
692#define SYSINIT_DOMAIN_REFERENCE(dom)                           \
693        SYSINIT_REFERENCE(domain_add_ ## dom)
694#endif /* __rtems__ */
695-------------------------------------------------------------------------------
696
697Here you see that the SYSINIT(9) entries are no longer static.  The
698\*_REFERENCE() macros will create references to the corresponding modules which
699are later resolved by the linker.  The application has to provide an object
700file with references to all required FreeBSD modules.
701
702The FreeBSD device model is quite elaborated (with follow-ups):
703
704http://www.freebsd.org/cgi/man.cgi?query=driver
705
706The devices form a tree with the Nexus device at a high-level.  This Nexus
707device is architecture specific in FreeBSD.  In RTEMS we have our own Nexus
708device, see `rtemsbsd/bsp/bsp-bsd-nexus-devices.c`.
709
710=== SYSCTL_NODE Example
711
712During development, we had an undefined reference to
713_bsd_sysctl__net_children that we had trouble tracking down. Thanks to
714Chris Johns, we located it. He explained how to read SYSCTL_NODE
715definitions. This line from freebsd/netinet/in_proto.c is attempting
716to add the "inet" node to the parent node "_net".
717
718----
719SYSCTL_NODE(_net,      PF_INET,         inet,   CTLFLAG_RW, 0,
720        "Internet Family");
721----
722
723Our problem was that we could not find where _bsd_sysctl__net_children
724was defined. Chris suggested that when in doubt compile with -save-temps
725and look at the preprocessed .i files. But he did not need that. He
726explained that this the symbol name _bsd_sysctl__net_children was
727automatically generated by a SYSCTL_NODE as follows:
728
729* _bsd_ - added by RTEMS modifications to SYSCTL_NODE macro
730* sysctl_ - boilerplace added by SYSCTL_NODE macro
731* "" - empty string for parent node
732* net - name of SYSCTL_NODE
733* children - added by SYSCTL macros
734 
735This was all generated by a support macro declaring the node as this:
736
737----
738struct sysctl_oid_list SYSCTL_NODE_CHILDREN(parent, name);
739----
740
741Given this information, we located this SYSCTL_NODE declaration in
742kern/kern_mib.c
743
744----
745SYSCTL_NODE(, CTL_KERN,   kern,   CTLFLAG_RW, 0,
746        "High kernel, proc, limits &c");
747----
748
749== Core FreeBSD APIs and RTEMS Replacements ==
750
751=== SX(9) (Shared/exclusive locks) ===
752
753http://www.freebsd.org/cgi/man.cgi?query=sx
754
755Binary semaphores (this neglects the ability to allow shared access).
756
757=== MUTEX(9) (Mutual exclusion) ===
758
759http://www.freebsd.org/cgi/man.cgi?query=mutex
760
761Binary semaphores (not recursive mutexes are not supported this way).
762
763=== RWLOCK(9) (Reader/writer lock) ===
764
765http://www.freebsd.org/cgi/man.cgi?query=rwlock
766
767POSIX r/w lock.
768
769=== RMLOCK(9) (Reader/writer lock optimized for mostly read access patterns) ===
770
771Note:  This object was implemented as a wrapper for RWLOCK in the rm_lock header file.
772
773http://www.freebsd.org/cgi/man.cgi?query=rmlock
774
775POSIX r/w lock.
776
777=== CONDVAR(9) (Condition variables) ===
778
779http://www.freebsd.org/cgi/man.cgi?query=condvar
780
781POSIX condition variables with modifications (hack).
782
783=== CALLOUT(9) (Timer functions) ===
784
785http://www.freebsd.org/cgi/man.cgi?query=callout
786
787Timer server.
788
789=== TASKQUEUE(9) (Asynchronous task execution) ===
790
791http://www.freebsd.org/cgi/man.cgi?query=taskqueue
792
793TBD.
794
795=== KTHREAD(9), KPROC(9) (Tasks) ===
796
797http://www.freebsd.org/cgi/man.cgi?query=kthread
798
799http://www.freebsd.org/cgi/man.cgi?query=kproc
800
801Tasks.
802
803=== ZONE(9) (Zone allocator) ===
804
805http://www.freebsd.org/cgi/man.cgi?query=zone
806
807TBD.
808
809=== devfs (Device file system) ===
810
811Dummy, IMFS or new implementation (currently dummy).
812
813=== psignal (Signals) ===
814
815TBD.  Seems to be not needed.
816
817=== poll, select ===
818
819TBD.  Seems to be not needed.
820
821=== RMAN(9) (Resource management) ===
822
823http://www.freebsd.org/cgi/man.cgi?query=rman
824
825TBD.  Seems to be not needed.
826
827=== DEVCLASS(9), DEVICE(9), DRIVER(9), MAKE_DEV(9) (Device management) ===
828
829http://www.freebsd.org/cgi/man.cgi?query=devclass
830
831http://www.freebsd.org/cgi/man.cgi?query=device
832
833http://www.freebsd.org/cgi/man.cgi?query=driver
834
835http://www.freebsd.org/cgi/man.cgi?query=make_dev
836
837Use FreeBSD implementation as far as possible.  FreeBSD has a nice API for
838dynamic device handling.  It may be interesting for RTEMS to use this API
839internally in the future.
840
841=== BUS_SPACE(9), BUS_DMA(9) (Bus and DMA access) ===
842
843http://www.freebsd.org/cgi/man.cgi?query=bus_space
844
845http://www.freebsd.org/cgi/man.cgi?query=bus_dma
846
847Likely BSP dependent.  A default implementation for memory mapped linear access
848is easy to provide.  The current heap implementation supports all properties
849demanded by bus_dma (including the boundary constraint).
850
851== RTEMS Replacements by File Description ==
852
853Note:  Files with a status of USB are used by the USB test and have at least
854been partially tested.  If they contain both USB and Nic, then they are used
855by both and MAY contain methods that have not been tested yet.  Files that
856are only used by the Nic test are the most suspect.
857
858----
859rtems-libbsd File:      rtems-bsd-assert.c
860FreeBSD File:           rtems-bsd-config.h redefines BSD_ASSERT.
861Description:            This file contains the support method rtems_bsd_assert_func().
862Status:                 USB, Nic
863
864rtems-libbsd File:      rtems-bsd-autoconf.c
865FreeBSD File:           FreeBSD has BSP specific autoconf.c
866Description:            This file contains configuration methods that are used to setup the system.
867Status:                 USB
868
869rtems-libbsd File:      rtems-bsd-bus-dma.c
870FreeBSD File:           FreeBSD has BSP specific busdma_machdep.c
871Description:           
872Status:                 USB, Nic
873
874rtems-libbsd File:      rtems-bsd-bus-dma-mbuf.c       
875FreeBSD File:           FreeBSD has BSP specific busdma_machdep.c
876Description:           
877Status:                 Nic
878
879rtems-libbsd File:      rtems-bsd-callout.c             
880FreeBSD File:           kern/kern_timeout.c
881Description:           
882Status:                 USB, Nic
883
884rtems-libbsd File:      rtems-bsd-cam.c
885FreeBSD File:           cam/cam_sim.c
886Description:           
887Status:                 USB
888
889rtems-libbsd File:      rtems-bsd-condvar.c             
890FreeBSD File:           kern/kern_condvar.c
891Description:           
892Status:                 USB
893
894rtems-libbsd File:      rtems-bsd-copyinout.c
895FreeBSD File:           bsp specific copyinout.c )
896Description:            Note: The FreeBSD file is split with some methods being in rtems-bsd-support
897Status:                 Nic
898
899rtems-libbsd File:      rtems-bsd-delay.c
900FreeBSD File:           bsp specific file with multiple names
901Description:           
902Status:                 USB, Nic
903
904rtems-libbsd File:      rtems-bsd-descrip.c
905FreeBSD File:           kern/kern_descrip.c
906Description:           
907Status:                 Nic
908
909rtems-libbsd File:      rtems-bsd-generic.c             
910FreeBSD File:           kern/sys_generic.c
911Description:           
912Status:                 Nic
913
914rtems-libbsd File:      rtems-bsd-init.c
915FreeBSD File:           N/A
916Description:           
917Status:                 USB, Nic
918
919rtems-libbsd File:      rtems-bsd-init-with-irq.c
920FreeBSD File:           N/A
921Description:           
922Status:                 USB, Nic
923
924rtems-libbsd File:      rtems-bsd-jail.c
925FreeBSD File:           kern/kern_jail.c
926Description:           
927Status:                 USB, Nic
928
929rtems-libbsd File:      rtems-bsd-lock.c
930FreeBSD File:           kern/subr_lock.c
931Description:           
932Status:                 USB, Nic
933
934rtems-libbsd File:      rtems-bsd-log.c         
935FreeBSD File:           kern/subr_prf.c
936Description:           
937Status:                 Nic
938
939rtems-libbsd File:      rtems-bsd-malloc.c
940FreeBSD File:           kern/kern_malloc.c
941Description:           
942Status:                 USB, Nic
943
944rtems-libbsd File:      rtems-bsd-mutex.c
945FreeBSD File:           kern/kern_mutex.c
946Description:           
947Status:                 USB, Nic
948
949rtems-libbsd File:      rtems-bsd-newproc.c
950FreeBSD File:           N/A
951Description:           
952Status:                 Nic
953
954rtems-libbsd File:      rtems-bsd-nexus.c
955FreeBSD File:           bsp specific nexus.c
956Description:           
957Status:                 USB
958
959rtems-libbsd File:      rtems-bsd-panic.c               
960FreeBSD File:           boot/common/panic.c
961Description:           
962Status:                 USB, Nic
963
964rtems-libbsd File:      rtems-bsd-rwlock.c             
965FreeBSD File:           kern_rwlock.c
966Description:           
967Status:                 USB, Nic
968
969rtems-libbsd File:      rtems-bsd-shell.c               
970FreeBSD File:           N/A
971Description:           
972Status:                 USB
973
974rtems-libbsd File:      rtems-bsd-signal.c             
975FreeBSD File:           kern/kern_sig.c
976Description:           
977Status:                 Nic
978
979rtems-libbsd File:      rtems-bsd-smp.c                 
980FreeBSD File:           N/A
981Description:           
982Status:                 Nic
983
984rtems-libbsd File:      rtems-bsd-support.c             
985FreeBSD File:           bsp specific copyinout.c
986Description:            Note: the FreeBSD file is split with some methods being in rtems-bsd-copyinout.
987Status:                 USB, Nic
988
989rtems-libbsd File:      rtems-bsd-sx.c                 
990FreeBSD File:           kern/kern_sx.c
991Description:            Status: USB, Nic
992
993rtems-libbsd File:      rtems-bsd-synch.c               
994FreeBSD File:           kern/kern_synch.c
995Description:           
996Status:                 USB, Nic
997
998rtems-libbsd File:      rtems-bsd-syscalls.c           
999FreeBSD File:           User API for kern/uipc_syscalls.c
1000Description:           
1001Status:                 Nic
1002
1003rtems-libbsd File:      rtems-bsd-sysctlbyname.c       
1004FreeBSD File:           User API for sysctlbyname(3)
1005Description:           
1006Status:
1007
1008rtems-libbsd File:      rtems-bsd-sysctl.c             
1009FreeBSD File:           User API for sysctl(8)
1010Description:           
1011Status:
1012
1013rtems-libbsd File:      rtems-bsd-sysctlnametomib.c     
1014FreeBSD File:           User API for sysctlnametomib
1015Description:           
1016Status:
1017
1018rtems-libbsd File:      rtems-bsd-taskqueue.c           
1019FreeBSD File:           kern/subr_taskqueue.c
1020Description:           
1021Status:                 Nic
1022
1023rtems-libbsd File:      rtems-bsd-thread.c                     
1024FreeBSD File:           kern/kern_kthread.c
1025Description:           
1026Status:                 USB, Nic
1027
1028rtems-libbsd File:      rtems-bsd-timeout.c             
1029FreeBSD File:           kern/kern_timeout.c
1030Description:           
1031Status:                 Nic
1032
1033rtems-libbsd File:      rtems-bsd-timesupport.c         
1034FreeBSD File:           kern/kern_clock.c
1035Description:           
1036Status:                 Nic
1037
1038rtems-libbsd File:      rtems-bsd-vm_glue.c             
1039FreeBSD File:           vm/vm_glue.c
1040Description:           
1041Status:                 USB, Nic
1042----
1043
1044== Notes by File ==
1045
1046altq_subr.c - Arbitrary choices were made in this file that RTEMS would
1047not support tsc frequency change.  Additionally, the clock frequency
1048for machclk_freq is always measured for RTEMS.
1049
1050conf.h - In order to add make_dev and destroy_dev, variables in the cdev
1051structure that were not being used were conditionally compiled out. The
1052capability of supporting children did not appear to be needed and was
1053not implemented in the rtems version of these routines.
1054 
1055== NICs Status ==
1056
1057----
1058Driver                  Symbol                          Status
1059======                  ======                          ======
1060RealTek                 _bsd_re_pcimodule_sys_init      Links
1061EtherExpress            _bsd_fxp_pcimodule_sys_init     Links
1062DEC tulip               _bsd_dc_pcimodule_sys_init      Links
1063Broadcom BCM57xxx       _bsd_bce_pcimodule_sys_init     Links
1064Broadcom BCM4401        _bsd_bfe_pcimodule_sys_init     Links
1065Broadcom BCM570x        _bsd_bge_pcimodule_sys_init     Needs Symbols (A)
1066E1000 IGB               _bsd_igb_pcimodule_sys_init     Links
1067E1000 EM                _bsd_em_pcimodule_sys_init      Links
1068----
1069
1070
1071Symbols (A)
1072         pci_get_vpd_ident
1073 
1074== Problems to report to FreeBSD ==
1075
1076The MMAP_NOT_AVAILABLE define is inverted on its usage.  When it is
1077defined the mmap method is called. Additionally, it is not used
1078thoroughly. It is not used in the unmap portion of the source.
1079The file rec_open.c uses the define MMAP_NOT_AVAILABLE to wrap
1080the call to mmap and file rec_close.c uses the munmap method.
1081
1082
1083
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