[RTEMS Project] #4750: Linker discards RTEMS_SYSINIT_ITEM object

[RTEMS trac]

#4750: Linker discards RTEMS_SYSINIT_ITEM object
---------------------+--------------------
  Reporter:  dsa93   |      Owner:  (none)
      Type:  defect  |     Status:  new
  Priority:  normal  |  Milestone:  6.1
 Component:  rtems   |    Version:  6
  Severity:  normal  |   Keywords:
Blocked By:          |   Blocking:
---------------------+--------------------
 Hi

 I am developing device driver in custom BSP in RTEMS.
 I applied my BSP on top of master branch.

 My driver code looks like this:


 {{{
 /* driver logic in "static" functions (omitted) */

 void custom_driver_init(void);

 RTEMS_SYSINIT_ITEM(
   custom_driver_init,
   RTEMS_SYSINIT_DEVICE_DRIVERS,
   RTEMS_SYSINIT_ORDER_SEVENTH
 );
 }}}

 It is discarded by linker. custom_driver_init is never called. I
 discovered hack how to make linker not discard this: if I put at least one
 extern linkage function and call it in other file then linker dont discard
 "custom_driver_init"

 {{{
 /* driver logic in "static" functions (omitted) */

 /* Call this function for example from main function */
 int workaraound(void) {
     return 5;
 }

 void custom_driver_init(void);

 RTEMS_SYSINIT_ITEM(
   custom_driver_init,
   RTEMS_SYSINIT_DEVICE_DRIVERS,
   RTEMS_SYSINIT_ORDER_SEVENTH
 );
 }}}

 Driver file compilation arguments:


 {{{
  -MMD,
  -Wall,
  -Wmissing-prototypes,
  -Wimplicit-function-declaration,
  -Wstrict-prototypes,
  -Wnested-externs,
  -O2,
  -g,
  -fdata-sections,
  -ffunction-sections,
  -mthumb,
  -mcpu=cortex-m7,
  -mfpu=fpv5-d16,
  -mfloat-abi=hard,
  -save-temps,
  -Icpukit/include,
  -I../../../cpukit/include,
  -Icpukit/score/cpu/arm/include,
  -I../../../cpukit/score/cpu/arm/include,
  -Ibsps/include,
  -I../../../bsps/include,
  -Ibsps/arm/include,
  -I../../../bsps/arm/include,
  ../../../bsps/arm/someplatform/console/console.c,
  -c,
  -DHAVE_CONFIG_H=1,
  -DBOARD_MAINCK_FREQ_HZ=10000000

 }}}

 Application linkage files

 {{{
 /home/dsa/rtems/rsb-6/bin/arm-rtems6-gcc
  -g
  -mthumb
  -mcpu=cortex-m7
  -mfpu=fpv5-d16
  -mfloat-abi=hard
  -DBOARD_MAINCK_FREQ_HZ=10000000
  -I/home/dsa/arm-rtems6/someplatform/lib/include
  -B/home/dsa/arm-rtems6/someplatform/lib
  -qrtems
  -Wl,--gc-sections
  -Wl,-Map=ecu-app.map,--print-memory-usage,--cref
  CMakeFiles/ecu-app.dir/src/main.c.obj
  -o ecu-app.elf
  -lrtemsbsp
  -lrtemscpu
 }}}

 I tried to research this topic and I am not sure if there is a way to
 prevent this optimisation, so I decided to post it here. I can provide you
 some more details or perform some tests

--
Ticket URL: <http://devel.rtems.org/ticket/4750>
RTEMS Project <http://www.rtems.org/>
RTEMS Project