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Re: Current state of multilib support (powerpc)



On 05/19/2016 12:15 AM, Thomas De Schampheleire wrote:

On Thu, May 19, 2016 at 8:13 AM, Alexey Neyman <stilor@att.net> wrote:
[..]

I created a toolchain based on that PR with the following configuration:

CT_PREFIX_DIR="${CT_TOP_DIR}/targets/${CT_TARGET}"
CT_ARCH_CPU="e6500"
CT_ARCH_64=y
CT_ARCH_powerpc=y
CT_MULTILIB=y
CT_KERNEL_linux=y
CT_KERNEL_V_3_18=y

CT_BINUTILS_EXTRA_CONFIG_ARRAY="--enable-targets=powerpc-linux,powerpc64-linux"
CT_CC_GCC_V_4_9_3=y

CT_CC_GCC_CORE_EXTRA_CONFIG_ARRAY="--enable-targets=powerpc-linux,powerpc64-linux"

CT_CC_GCC_EXTRA_CONFIG_ARRAY="--enable-targets=powerpc-linux,powerpc64-linux"
CT_CC_GCC_MULTILIB_LIST="powerpc-linux,powerpc64-linux"
CT_CC_LANG_CXX=y

The idea is that 32-bit should be the default, without requiring
additional options on the compiler command-line.

When passing this toolchain to buildroot, applications seems to build
fine in 32-bit (I did not try to run them yet).
The kernel is also correctly built in 64-bit.
However, there is something wrong for u-boot. I get errors like:

The fact that both 32- and 64-bit applications compile fine indicate that
gcc indeed is passing the options to ld correctly. I tried building a simple
app in 32- and 64-bit modes, with -v, and the output shows that in 64-bit
mode, -m64 is added to the arguments - as expected.


/foo/output/host/usr/bin/powerpc64-unknown-linux-gnu-ld.bfd:
Relocatable linking with relocations from format elf32-powerpc
(arch/powerpc/cpu/mpc8xxx/cpu.o) to format elf64-powerpc
(arch/powerpc/cpu/mpc8xxx/built-in.o) is not supported

Which target are you building? I tried some random powerpc target
(xpedite517x_defconfig) and the build failed due to some invalid assembly
but went past mpc8xxx/built-in.o:

   CC      arch/powerpc/cpu/mpc8xxx/cpu.o
   CC      arch/powerpc/cpu/mpc8xxx/fdt.o
   CC      arch/powerpc/cpu/mpc8xxx/fsl_lbc.o
   CC      arch/powerpc/cpu/mpc8xxx/law.o
   LD      arch/powerpc/cpu/mpc8xxx/built-in.o
   LD      arch/powerpc/cpu/built-in.o
   AS      arch/powerpc/cpu/mpc86xx/cache.o
   CC      arch/powerpc/cpu/mpc86xx/cpu.o
   CC      arch/powerpc/cpu/mpc86xx/cpu_init.o
   CC      arch/powerpc/cpu/mpc86xx/fdt.o
   CC      arch/powerpc/cpu/mpc86xx/interrupts.o
   CC      arch/powerpc/cpu/mpc86xx/mpc8641_serdes.o
   CC      arch/powerpc/cpu/mpc86xx/speed.o
   LD      arch/powerpc/cpu/mpc86xx/built-in.o
   AS      arch/powerpc/cpu/mpc86xx/start.o
arch/powerpc/cpu/mpc86xx/start.S: Assembler messages:
arch/powerpc/cpu/mpc86xx/start.S:466: Error: missing operand

Hard to say what went wrong without the name of the target that failed for
you. It looks, however, like U-Boot's build system expects binutils/gcc to
default to exact CPU for the target - not surprising given the variety of
PowerPC assembly dialects...


The target is a custom board not available in upstream uboot. It is based on
Freescale T2080. I don't have the repo at hand, I can check later if there
is a similar upstream target that shows the same problem...

If you cannot find a similar board, at least capture the commands that
compiled the objects that went into linking, and the link command itself.
With a bit of luck that may be sufficient to reproduce the issue :)



I can reproduce the issue with the upstream config called 'T2080RDB'.
Excerpt from the log:


/foo/output/host/usr/bin/powerpc64-unknown-linux-gnu-gcc
-Wp,-MD,board/freescale/common/.fman.o.d  -nostdinc -isystem
/foo/output/host/opt/ext-toolchain/bin/../lib/gcc/powerpc64-unknown-linux-gnu/4.9.3/include
-Iinclude  -I./arch/powerpc/include -I./board/isam_common
-I./board/freescale/t208xrdb -include ./include/linux/kconfig.h
-D__KERNEL__ -D__UBOOT__ -DCONFIG_SYS_TEXT_BASE=0xeff40000 -Wall
-Wstrict-prototypes -Wno-format-security -fno-builtin -ffreestanding
-Os -fno-stack-protector -g -fstack-usage -Wno-format-nonliteral
-Werror=date-time -D__powerpc__ -ffixed-r2 -Wa,-me500 -msoft-float
-mno-string -fno-delete-null-pointer-checks -mno-spe -fpic
-mrelocatable -ffunction-sections -fdata-sections -meabi -pipe
-D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(fman)"
-D"KBUILD_MODNAME=KBUILD_STR(fman)" -c -o
board/freescale/common/fman.o board/freescale/common/fman.c

/foo/output/host/usr/bin/powerpc64-unknown-linux-gnu-ld.bfd   -n   -r
-o board/freescale/common/built-in.o board/freescale/common/fman.o
board/freescale/common/vid.o board/freescale/common/sys_eeprom.o

/foo/output/host/usr/bin/powerpc64-unknown-linux-gnu-ld.bfd:
Relocatable linking with relocations from format elf32-powerpc
(board/freescale/common/fman.o) to format elf64-powerpc
(board/freescale/common/built-in.o) is not supported
s


Be aware that I'm building with Buildroot, meaning that the compiler
(not linker) is wrapped. When calling that wrapper, the real compiler
is called with following extra options:

--sysroot' '/home/tdescham/repo/isam/buildroot-fantg/output/host/usr/powerpc-buildroot-linux-gnu/sysroot'
'-mcpu=e6500'
I don't have your buildroot tree; I tried creating the wrapper with just -mcpu=e6500 added. But it fails in U-Boot build for T2080_RDB even before linking built-in.o: 

  CC      arch/powerpc/cpu/mpc8xxx/cpu.o
{standard input}: Assembler messages:
{standard input}:512: Error: junk at end of line: `128'
scripts/Makefile.build:280: recipe for target 'arch/powerpc/cpu/mpc8xxx/cpu.o' failed 
make[2]: *** [arch/powerpc/cpu/mpc8xxx/cpu.o] Error 1
Using U-Boot 2016.05. Which version are you using? Is it possible that the sysroot contains something that changes GCC options (e.g. a gcc spec file)?
I did reproduce your issue, though, by running the commands you quoted above, manually.
The problem is that U-boot invokes ld directly, not through gcc; and ld is indeed defaulting to 64-bit. You toolchain config supplies --enable-targets to binutils configure, but binutils configure does not handle this option; the preferred mode is established by the supplied target.
Hence, you should build for powerpc, not for powerpc64 - that still allows --enable-targets option to gcc configure, so you'll still be able to build 64-bit binaries: 

--- email-defconfig    2016-05-18 20:02:57.565718947 -0700
+++ email-defconfig.mod    2016-05-20 20:34:22.566050597 -0700
@@ -1,11 +1,9 @@
 CT_PREFIX_DIR="${CT_TOP_DIR}/targets/${CT_TARGET}"
 CT_ARCH_CPU="e6500"
-CT_ARCH_64=y
 CT_ARCH_powerpc=y
 CT_MULTILIB=y
 CT_KERNEL_linux=y
 CT_KERNEL_V_3_18=y
-CT_BINUTILS_EXTRA_CONFIG_ARRAY="--enable-targets=powerpc-linux,powerpc64-linux"
 CT_CC_GCC_V_4_9_3=y
 CT_CC_GCC_CORE_EXTRA_CONFIG_ARRAY="--enable-targets=powerpc-linux,powerpc64-linux"
 CT_CC_GCC_EXTRA_CONFIG_ARRAY="--enable-targets=powerpc-linux,powerpc64-linux"


Alexey.



Thanks,
Thomas




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