[RTEMS Project] #4443: powerpc/motorola_powerpc BSPs build bootloader with -msoft-float

[RTEMS trac]

#4443: powerpc/motorola_powerpc BSPs build bootloader with -msoft-float
-----------------------------+--------------------
  Reporter:  Andrew Johnson  |      Owner:  (none)
      Type:  defect          |     Status:  new
  Priority:  normal          |  Milestone:
 Component:  admin           |    Version:  5
  Severity:  normal          |   Keywords:
Blocked By:                  |   Blocking:
-----------------------------+--------------------
 While working on the EPICS port to RTEMS-5 and trying to link an EPICS
 test application into a bootable binary for the mvme2100 BSP built with
 RTEMS-5.1, I get this error:
 {{{
 /usr/local/rtems-5.1/bin/powerpc-rtems5-ld: libComTestHarness uses hard
 float, /usr/local/rtems-5.1/powerpc-rtems5/mvme2100/lib/bootloader.o uses
 soft float
 /usr/local/rtems-5.1/bin/powerpc-rtems5-ld: failed to merge target
 specific data of file libComTestHarness
 }}}
 The `libComTestHarness` is the EPICS test application. I get the same
 error with the mvme2307 BSP, which is part of the same
 `powerpc/motorola_powerpc` BSP family as the mvme2100.

 After investigation I found that a recent version of binutils has made
 linking soft-float code with hard-float an error instead of just emitting
 a warning, which may be why this problem hasn't come up before. I don't
 see that warning when I build for the mvme2100 with RTEMS-4.9.2 but the
 warning message may have been added more recently than the version of
 binutils used for that release.

 This is coming from the `AM_CFLAGS` definition in
 `c/src/lib/libbsp/powerpc/motorola_powerpc/bootloader/Makefile.am` which
 includes the flag `-msoft-float` whereas all of the motorola_powerpc
 boards have an FPU as far as I know (none of the BSP `config/*.cfg` files
 provide that flag). Thus I first tried removing just that flag:
 {{{#!patch
 diff --git
 a/c/src/lib/libbsp/powerpc/motorola_powerpc/bootloader/Makefile.am
 b/c/src/lib/libbsp/powerpc/motorola_powerpc/bootloader/Makefile.am
 index 42b70544e6..1b4b95b14c 100644
 --- a/c/src/lib/libbsp/powerpc/motorola_powerpc/bootloader/Makefile.am
 +++ b/c/src/lib/libbsp/powerpc/motorola_powerpc/bootloader/Makefile.am
 @@ -21,7 +21,7 @@ bootloader_SOURCES +=
 ../../../../../../../bsps/powerpc/motorola_powerpc/bootloa
  # Remove references to EABI when compiling bootloader
  BOOTLOADER_CPU_CFLAGS=$(subst -msdata=eabi,,$(subst
 -meabi,,$(CPU_CFLAGS)))
  AM_CPPFLAGS = -D__BOOT__ @RTEMS_CPPFLAGS@ @RTEMS_BSP_CPPFLAGS@
 -AM_CFLAGS = -mrelocatable -msoft-float \
 +AM_CFLAGS = -mrelocatable \
      -mstrict-align -fno-builtin -Wall -mmultiple -mstring -O2 \
      -fomit-frame-pointer -ffixed-r13 -mno-sdata $(BOOTLOADER_CPU_CFLAGS)
  AM_CCASFLAGS = $(AM_CPPFLAGS) \
 }}}
 However that doesn't seem to be enough, the result gives this application
 build error instead:
 {{{
 /usr/local/rtems-5.1/bin/powerpc-rtems5-objcopy -O binary -R .comment -S
 libComTestHarness rtems
 gzip -f9 rtems
 /usr/local/rtems-5.1/bin/powerpc-rtems5-ld -o libComTestHarness.boot
 /usr/local/rtems-5.1/powerpc-rtems5/mvme2100/lib/bootloader.o --just-
 symbols=libComTestHarness -b binary rtems.gz -T /usr/local/rtems-5.1
 /powerpc-rtems5/mvme2100/lib/ppcboot.lds -Map libComTestHarness.map
 /usr/local/rtems-5.1/bin/powerpc-rtems5-ld: libComTestHarness: compiled
 normally and linked with modules compiled with -mrelocatable
 /usr/local/rtems-5.1/bin/powerpc-rtems5-ld: failed to merge target
 specific data of file libComTestHarness
 }}}
 I don't have a good feel for exactly what the `-mrelocatable` flag is
 doing, but the documentation implied something like it is probably needed
 in this case. It also showed a similar but apparently more liberal
 `-mrelocatable-lib` flag. On applying this change and rebuilding the BSP I
 was able to get my EPICS build to succeed:
 {{{#!patch
 diff --git
 a/c/src/lib/libbsp/powerpc/motorola_powerpc/bootloader/Makefile.am
 b/c/src/lib/libbsp/powerpc/motorola_powerpc/bootloader/Makefile.am
 index 42b70544e6..92d6e21f40 100644
 --- a/c/src/lib/libbsp/powerpc/motorola_powerpc/bootloader/Makefile.am
 +++ b/c/src/lib/libbsp/powerpc/motorola_powerpc/bootloader/Makefile.am
 @@ -21,11 +21,11 @@ bootloader_SOURCES +=
 ../../../../../../../bsps/powerpc/motorola_powerpc/bootloa
  # Remove references to EABI when compiling bootloader
  BOOTLOADER_CPU_CFLAGS=$(subst -msdata=eabi,,$(subst
 -meabi,,$(CPU_CFLAGS)))
  AM_CPPFLAGS = -D__BOOT__ @RTEMS_CPPFLAGS@ @RTEMS_BSP_CPPFLAGS@
 -AM_CFLAGS = -mrelocatable -msoft-float \
 +AM_CFLAGS = -mrelocatable-lib \
      -mstrict-align -fno-builtin -Wall -mmultiple -mstring -O2 \
      -fomit-frame-pointer -ffixed-r13 -mno-sdata $(BOOTLOADER_CPU_CFLAGS)
  AM_CCASFLAGS = $(AM_CPPFLAGS) \
 -    -mrelocatable -DASM $(BOOTLOADER_CPU_CFLAGS)
 +    -mrelocatable-lib -DASM $(BOOTLOADER_CPU_CFLAGS)

  #
  # CAUTION :
 }}}

 I don't have a VME chassis or an MVME2100 board at home with me to test
 with, but I hope to be able to check if the result boots and works
 properly once I get back into the office (which might be a few weeks
 though). I'm filing this ticket now to see if anyone else has come across
 or already solved this problem, and to see if the solution looks
 reasonable to those with more experience.

 Any comments?

--
Ticket URL: <http://devel.rtems.org/ticket/4443>
RTEMS Project <http://www.rtems.org/>
RTEMS Project