[Buildroot] [Bug 6842] New: Checking external toolchain for eabihf

[Buildroot] [Bug 6842] New: Checking external toolchain for eabihf

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6842

           Summary: Checking external toolchain for eabihf
           Product: buildroot
           Version: 2014.02
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: minor
          Priority: P5
         Component: Other
        AssignedTo: unassigned at buildroot.uclibc.org
        ReportedBy: syntheticpp at gmx.net
                CC: buildroot at uclibc.org
   Estimated Hours: 0.0


http://lists.busybox.net/pipermail/buildroot/2014-January/087860.html

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[Buildroot] [Bug 6842] Checking external toolchain for eabihf

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6842

--- Comment #1 from Thomas De Schampheleire <patrickdepinguin+buildroot@gmail.com> 2014-02-07 08:30:47 UTC ---
Thomas Petazzoni, could you shine your light on this patch?
Copy/pasted here for convenience:

diff --git a/toolchain/helpers.mk b/toolchain/helpers.mk
index faa9d90..c41d757 100644
--- a/toolchain/helpers.mk
+++ b/toolchain/helpers.mk
@@ -284,8 +284,8 @@ check_arm_abi = \
         echo "External toolchain uses the unsuported OABI" ; \
         exit 1 ; \
     fi ; \
-    EXT_TOOLCHAIN_CRT1=`LANG=C $${__CROSS_CC} -print-file-name=crt1.o` ; \
-    if $${__CROSS_READELF} -A $${EXT_TOOLCHAIN_CRT1} | grep -q
"Tag_ABI_VFP_args:" ; then \
+    EXT_TOOLCHAIN_LIBM=`LANG=C $${__CROSS_CC} -print-file-name=libm.so` ; \
+    if $${__CROSS_READELF} -A $${EXT_TOOLCHAIN_LIBM} | grep -q
"Tag_ABI_VFP_args:" ; then \
         EXT_TOOLCHAIN_ABI="eabihf" ; \
     else \
         EXT_TOOLCHAIN_ABI="eabi" ; \

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[Buildroot] [Bug 6842] Checking external toolchain for eabihf

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6842

--- Comment #2 from Thomas De Schampheleire <patrickdepinguin+buildroot@gmail.com> 2014-02-21 07:50:06 UTC ---
Patch resubmitted to the list: http://patchwork.ozlabs.org/patch/320459/
Discussion started, but needs followup.

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[Buildroot] [Bug 6842] Checking external toolchain for eabihf

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6842

--- Comment #3 from syntheticpp at gmx.net 2014-02-23 16:32:24 UTC ---
Investigated it further: there are no problems when eglibc is used, only with
uclibc.

A grep for 'hard' or "EABI" in the uclibc-0.9.33.2 sources shows nothing
relevant, so I assume eabihf is not supported by uclibc.

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[Buildroot] [Bug 6842] Checking external toolchain for eabihf

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6842

--- Comment #4 from Thomas Petazzoni <thomas.petazzoni@free-electrons.com> 2014-02-23 17:37:22 UTC ---
(In reply to comment #3)
> Investigated it further: there are no problems when eglibc is used, only with
> uclibc.

Correct.

> 
> A grep for 'hard' or "EABI" in the uclibc-0.9.33.2 sources shows nothing
> relevant, so I assume eabihf is not supported by uclibc.

I don't think the C library needs anything to "support" eabihf. eabihf is all
about a change in the calling convention of functions taking floating point
arguments.

I haven't got the bottom of this problem yet, but I have indeed reproduced it,
and I continue to believe that the fix is *not* to change the external
toolchain check, but instead to investigate *why* the uClibc crt1.o does not
have those flags when built with the internal toolchain backend.

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[Buildroot] [Bug 6842] Checking external toolchain for eabihf

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6842

--- Comment #5 from syntheticpp at gmx.net 2014-02-23 18:22:52 UTC ---
> 
> the fix is *not* to change the external toolchain check, 

Yes, the patch should not be applied.

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[Buildroot] [Bug 6842] Checking external toolchain for eabihf

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6842

--- Comment #6 from syntheticpp at gmx.net 2014-02-23 20:03:10 UTC ---
command line for crtl1.o looks like this:

$ /opt/testgcc4.8.2/usr/bin/arm-buildroot-linux-uclibcgnueabihf-gcc -c
libc/sysdeps/linux/arm/crt1.S -o lib/crt1.o -include ./include/libc-symbols.h
-Wall -Wstrict-prototypes -Wstrict-aliasing -funsigned-char -fno-builtin
-fno-asm -mlittle-endian -fno-stack-protector -nostdinc -I./include -I./include
-I. -I./libc/sysdeps/linux -I./libc/sysdeps/linux/arm -Os -funit-at-a-time
-fmerge-all-constants -fstrict-aliasing -fno-tree-loop-optimize
-fno-tree-dominator-opts -fno-strength-reduce -DHAVE_FORCED_UNWIND
-I./libpthread/nptl -I./libpthread/nptl
-I./libpthread/nptl/sysdeps/unix/sysv/linux/arm/
-I./libpthread/nptl/sysdeps/unix/sysv/linux/arm -I./libpthread/nptl/sysdeps/arm
-I./libpthread/nptl/sysdeps/arm -I./libpthread/nptl/sysdeps/unix/sysv/linux
-I./libpthread/nptl/sysdeps/unix/sysv/linux -I./libpthread/nptl/sysdeps/pthread
-I./libpthread/nptl/sysdeps/pthread/bits -I./libpthread/nptl/sysdeps/generic
-I./ldso/ldso/arm -I./ldso/include -I./libc/sysdeps/linux/common
-I/opt/testgcc4.8.2/usr/arm-buildroot-linux-uclibcgnueabihf/sysroot/usr/include/
-isystem
/opt/testgcc4.8.2/usr/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/4.8.2/include-fixed
-isystem
/opt/testgcc4.8.2/usr/lib/gcc/arm-buildroot-linux-uclibcgnueabihf/4.8.2/include
-DNDEBUG -D__USE_STDIO_FUTEXES__ -MT lib/crt1.o -MD -MP -MF lib/.crt1.o.dep
-D__ASSEMBLER__ -Wa,--noexecstack    -DL_crt1

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[Buildroot] [Bug 6842] Checking external toolchain for eabihf

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6842

--- Comment #7 from Stefan S?rensen <stefan.sorensen@spectralink.com> 2014-02-24 08:24:25 UTC ---
(In reply to comment #4)

> I haven't got the bottom of this problem yet, but I have indeed reproduced it,
> and I continue to believe that the fix is *not* to change the external
> toolchain check, but instead to investigate *why* the uClibc crt1.o does not
> have those flags when built with the internal toolchain backend.

The attributes are added by the compiler, not the assembler. glibc has both c
and assembler source for crt1.o while uclibc has only assembler source.

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[Buildroot] [Bug 6842] Checking external toolchain for eabihf

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6842

--- Comment #8 from Thomas De Schampheleire <patrickdepinguin+buildroot@gmail.com> 2014-02-28 13:01:10 UTC ---
Config file for toolchain:
BR2_arm=y
BR2_cortex_a8=y
BR2_ARM_EABIHF=y
BR2_ARM_FPU_VFPV3=y
BR2_TOOLCHAIN_BUILDROOT_LARGEFILE=y
BR2_TOOLCHAIN_BUILDROOT_INET_IPV6=y
BR2_TOOLCHAIN_BUILDROOT_LOCALE=y
BR2_BINUTILS_VERSION_2_24=y
BR2_GCC_VERSION_4_8_X=y
BR2_TOOLCHAIN_BUILDROOT_CXX=y
BR2_ENABLE_LOCALE_PURGE=y
BR2_ENABLE_LOCALE_WHITELIST="C en_US de "


I can indeed confirm that uClibc builds crt1.o from crt1.S, using the command
line as specified in comment #7.

Looking in the binutils sources (that creates the assembler), I do find
references to ABI_VFP, but I don't see places where it is actually emitted in
the build, unless the source assembly file contains a statement
.eabi_attribute.

So the statements made by the submitter seem to be valid.

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[Buildroot] [Bug 6842] Checking external toolchain for eabihf

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6842

--- Comment #9 from Thomas De Schampheleire <patrickdepinguin+buildroot@gmail.com> 2014-05-05 12:14:23 UTC ---
Alternative patch submitted by Stefan S?rensen, updated and tested today by me:
http://patchwork.ozlabs.org/patch/345703/

This patch compiles a temporary object instead of using libm or crt1.

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[Buildroot] [Bug 6842] Checking external toolchain for eabihf

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6842

Thomas De Schampheleire <patrickdepinguin+buildroot@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |2014.05

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[Buildroot] [Bug 6842] Checking external toolchain for eabihf

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6842

Thomas De Schampheleire <patrickdepinguin+buildroot@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED

--- Comment #10 from Thomas De Schampheleire <patrickdepinguin+buildroot@gmail.com> 2014-05-11 19:33:22 UTC ---
Fixed with
http://git.buildroot.net/buildroot/commit/?id=3787592063b0f30c69d074534a5a437bb458fbd7

Thanks for reporting!

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