sim/README-HACKING

   1 This is a loose collection of notes for people hacking on simulators.
   2 If this document gets big enough it can be prettied up then.
   3
   4 Contents
   5
   6 - The "common" directory
   7 - Common Makefile Support
   8 - TAGS support
   9 - Generating "configure" files
  10 - tconfig.in
  11 - C Language Assumptions
  12 - "dump" commands under gdb
  13 \f
  14 The "common" directory
  15 ======================
  16
  17 The common directory contains:
  18
  19 - common documentation files (e.g. run.1, and maybe in time .texi files)
  20 - common source files (e.g. run.c)
  21 - common Makefile fragment and configury (e.g. Make-common.in, aclocal.m4).
  22
  23 In addition "common" contains portions of the system call support
  24 (e.g. callback.c, nltvals.def).
  25
  26 Even though no files are built in this directory, it is still configured
  27 so support for regenerating nltvals.def is present.
  28 \f
  29 Common Makefile Support
  30 =======================
  31
  32 A common configuration framework is available for simulators that want
  33 to use it.  The common framework exists to remove a lot of duplication
  34 in configure.in and Makefile.in, and it also provides a foundation for
  35 enhancing the simulators uniformly (e.g. the more they share in common
  36 the easier a feature added to one is added to all).
  37
  38 The configure.in of a simulator using the common framework should look like:
  39
  40 --- snip ---
  41 dnl Process this file with autoconf to produce a configure script.
  42 sinclude(../common/aclocal.m4)
  43 AC_PREREQ(2.5)dnl
  44 AC_INIT(Makefile.in)
  45
  46 SIM_AC_COMMON
  47
  48 ... target specific additions ...
  49
  50 SIM_AC_OUTPUT
  51 --- snip ---
  52
  53 SIM_AC_COMMON:
  54
  55 - invokes the autoconf macros most often used by the simulators
  56 - defines --enable/--with options usable by all simulators
  57 - initializes sim_link_files/sim_link_links as the set of symbolic links
  58   to set up
  59
  60 SIM_AC_OUTPUT:
  61
  62 - creates the symbolic links defined in sim_link_{files,links}
  63 - creates config.h
  64 - creates the Makefile
  65
  66 The Makefile.in of a simulator using the common framework should look like:
  67
  68 --- snip ---
  69 # Makefile for blah ...
  70 # Copyright blah ...
  71
  72 ## COMMON_PRE_CONFIG_FRAG
  73
  74 # These variables are given default values in COMMON_PRE_CONFIG_FRAG.
  75 # We override the ones we need to here.
  76 # Not all of these need to be mentioned, only the necessary ones.
  77 # In fact it is better to *not* mention ones if the value is the default.
  78
  79 # List of object files, less common parts.
  80 SIM_OBJS =
  81 # List of extra dependencies.
  82 # Generally this consists of simulator specific files included by sim-main.h.
  83 SIM_EXTRA_DEPS =
  84 # List of flags to always pass to $(CC).
  85 SIM_EXTRA_CFLAGS =
  86 # List of extra libraries to link with.
  87 SIM_EXTRA_LIBS =
  88 # List of extra program dependencies.
  89 SIM_EXTRA_LIBDEPS =
  90 # List of main object files for `run'.
  91 SIM_RUN_OBJS = run.o
  92 # Dependency of `all' to build any extra files.
  93 SIM_EXTRA_ALL =
  94 # Dependency of `install' to install any extra files.
  95 SIM_EXTRA_INSTALL =
  96 # Dependency of `clean' to clean any extra files.
  97 SIM_EXTRA_CLEAN =
  98
  99 ## COMMON_POST_CONFIG_FRAG
 100
 101 # Rules need to build $(SIM_OBJS), plus whatever else the target wants.
 102
 103 ... target specific rules ...
 104 --- snip ---
 105
 106 COMMON_{PRE,POST}_CONFIG_FRAG are markers for SIM_AC_OUTPUT to tell it
 107 where to insert the two pieces of common/Make-common.in.
 108 The resulting Makefile is created by doing autoconf substitions on
 109 both the target's Makefile.in and Make-common.in, and inserting
 110 the two pieces of Make-common.in into the target's Makefile.in at
 111 COMMON_{PRE,POST}_CONFIG_FRAG.
 112
 113 Note that SIM_EXTRA_{INSTALL,CLEAN} could be removed and "::" targets
 114 could be used instead.  However, it's not clear yet whether "::" targets
 115 are portable enough.
 116 \f
 117 TAGS support
 118 ============
 119
 120 Many files generate program symbols at compile time.
 121 Such symbols can't be found with grep nor do they normally appear in
 122 the TAGS file.  To get around this, source files can add the comment
 123
 124 /* TAGS: foo1 foo2 */
 125
 126 where foo1, foo2 are program symbols.  Symbols found in such comments
 127 are greppable and appear in the TAGS file.
 128 \f
 129 Generating "configure" files
 130 ============================
 131
 132 For targets using the common framework, "configure" can be generated
 133 by running `autoconf'.
 134
 135 To regenerate the configure files for all targets using the common framework:
 136
 137         $  cd devo/sim
 138         $  make -f Makefile.in SHELL=/bin/sh autoconf-common
 139
 140 To add a change-log entry to the ChangeLog file for each updated
 141 directory (WARNING - check the modified new-ChangeLog files before
 142 renaming):
 143
 144         $  make -f Makefile.in SHELL=/bin/sh autoconf-changelog
 145         $  more */new-ChangeLog
 146         $  make -f Makefile.in SHELL=/bin/sh autoconf-install
 147
 148 In a similar vein, both the configure and config.in files can be
 149 updated using the sequence:
 150
 151         $  cd devo/sim
 152         $  make -f Makefile.in SHELL=/bin/sh autoheader-common
 153         $  make -f Makefile.in SHELL=/bin/sh autoheader-changelog
 154         $  more */new-ChangeLog
 155         $  make -f Makefile.in SHELL=/bin/sh autoheader-install
 156 \f
 157 tconfig.in
 158 ==========
 159
 160 File tconfig.in defines one or more target configuration macros
 161 (e.g. a tm.h file).  There are very few that need defining.
 162 For a list of all of them, see common/tconfig.in.
 163 It contains them all, commented out.
 164 The intent is that a new port can just copy this file and
 165 define the ones it needs.
 166 \f
 167 C Language Assumptions
 168 ======================
 169
 170 The programmer may assume that the simulator is being built using an
 171 ANSI C compiler that supports a 64 bit data type.  Consequently:
 172
 173         o       prototypes can be used (although using
 174                 PARAMS() and K&R declarations wouldn't
 175                 go astray).
 176
 177         o       If sim-types.h is included, the two
 178                 types signed64 and unsigned64 are
 179                 available.
 180
 181         o       The type `unsigned' is valid.
 182
 183 However, the user should be aware of the following:
 184
 185         o       GCC's `<number>LL' is NOT acceptable.
 186                 Microsoft-C doesn't reconize it.
 187
 188         o       MSC's `<number>i64' is NOT acceptable.
 189                 GCC doesn't reconize it.
 190
 191         o       GCC's `long long' MSC's `_int64' can
 192                 NOT be used to define 64 bit integer data
 193                 types.
 194
 195         o       An empty array (eg int a[0]) is not valid.
 196
 197 When building with GCC it is effectivly a requirement that
 198 --enable-build-warnings=,-Werror be specified during configuration.
 199 \f
 200 "dump" commands under gdb
 201 =========================
 202
 203 gdbinit.in contains the following
 204
 205 define dump
 206 set sim_debug_dump ()
 207 end
 208
 209 Simulators that define the sim_debug_dump function can then have their
 210 internal state pretty printed from gdb.
 211
 212 FIXME: This can obviously be made more elaborate.  As needed it will be.
 213 \f
 214 Rebuilding nltvals.def
 215 ======================
 216
 217 Checkout a copy of the SIM and LIBGLOSS modules (Unless you've already
 218 got one to hand):
 219
 220         $  mkdir /tmp/$$
 221         $  cd /tmp/$$
 222         $  cvs checkout sim-no-testsuite libgloss-no-testsuite newlib-no-testsuite
 223
 224 Configure things for an arbitrary simulator target (I've d10v for
 225 convenience):
 226
 227         $  mkdir /tmp/$$/build
 228         $  cd /tmp/$$/build
 229         $  /tmp/$$/devo/configure --target=d10v-elf
 230
 231 In the sim/common directory rebuild the headers:
 232
 233         $  cd sim/common
 234         $  make headers
 235
 236 To add a new target:
 237
 238         devo/sim/common/gennltvals.sh
 239
 240                 Add your new processor target (you'll need to grub
 241                 around to find where your syscall.h lives).
 242
 243         devo/sim/<processor>/Makefile.in
 244
 245                 Add the definition:
 246
 247                         ``NL_TARGET = -DNL_TARGET_d10v''
 248
 249                 just before the line COMMON_POST_CONFIG_FRAG.
 250
 251         devo/sim/<processor>/*.[ch]
 252
 253                 Include targ-vals.h instead of syscall.h.
 254