[RTEMS Project] #4504: RTEMS6 has incorrect code generation for stm32f4 bsp

[RTEMS trac]

#4504: RTEMS6 has incorrect code generation for stm32f4 bsp
-----------------------------+----------------------------------
  Reporter:  Andrei Chichak  |      Owner:  (none)
      Type:  defect          |     Status:  new
  Priority:  normal          |  Milestone:
 Component:  tool/gcc        |    Version:  6
  Severity:  normal          |   Keywords:  gcc multilib stm32f4
Blocked By:                  |   Blocking:
-----------------------------+----------------------------------
 I'm working with the master head targeting arm/stm32f4 for RTEMS 6.

 I built the tools and RTEMS using:

 {{{
 mkdir -p rtems/6
 export PREFIX=`pwd`/rtems/6
 mkdir external
 cd external
 git clone git://git.rtems.org/rtems.git
 git clone git://git.rtems.org/rtems-source-builder.git
 cd rtems-source-builder/rtems
 ../source-builder/sb-set-builder --prefix=${PREFIX} --log=../b-rsb-
 toolchain-arm.log 6/rtems-arm
 cd ../../rtems
 ./waf bsp_defaults --rtems-bsps=arm/stm32f4 > config.ini
 ./waf configure --prefix=${PREFIX}
 ./waf
 }}}

 This setup gives me code that faults when calling the memset() function
 from bsp_start_clear_bss(). The version of memset() being used in any of
 the compiled samples has the flags (from rtems-execinfo -O) of:

 {{{
    | memset.c                          : -mcpu=arm7tdmi -marm
 -march=armv4t
 }}}
  whereas other functions in the executable have:

 {{{
    | lseek.c                           : -mthumb -mcpu=cortex-m4
 -march=armv7e-m
 }}}

 If I rebuild with

 {{{
 ./waf bsp_defaults --rtems-bsps=arm/stm32f105rc > config.ini
 }}}

 then all of the functions are compiled with the correct architecture flags
 for a 105rc and the program can reach Init() when run on a 105rc chip.

 {{{
  Common flags: 3
   | -mthumb -mcpu=cortex-m3 -march=armv7-m
 }}}

 If I configure for stm32f4 and change the config.ini file to use:

 {{{
 ABI_FLAGS = -mthumb -mcpu=cortex-m3
 }}}

 Then rtems-exeinfo shows that all functions are using the same common
 flags as the stm32f105rc bsp configuration. The generated code cannot be
 used on an stm32f407, but it does compile an executable with one
 consistent instruction set.

 So, providing -mcpu=cortex-m4 in ABI_FLAGS triggers the use of the wrong
 version of functions from libgcc (I think).

--
Ticket URL: <http://devel.rtems.org/ticket/4504>
RTEMS Project <http://www.rtems.org/>
RTEMS Project