Re: Is "-mcpu" properly propagated?

[Erik Leunissen <elns at xs4all dot nl>]

An answer to myself:


On 21/02/15 11:58, Erik Leunissen wrote:
> Hi all,
>
> I've built a toolchain for arm, cortex-a8.
>
> The ct-ng configuration ("ct-ng savedefconfig; cat defconfig"), states:
>
>      CT_ARCH_ARCH="armv7-a"
>      CT_ARCH_CPU="cortex-a8"
>      CT_ARCH_TUNE="cortex-a8"
>
> The output of "*-gcc -Q --help=target", states:

Doing instead:

       *-gcc -v

shows the gcc configuration and all is as configured by ct-ng.


What I observed is probably a red herring. I don't understand well 
enough what

      "*-gcc -Q --help=target"

is supposed to output (just took it willy-nilly from some place on the 
internet). Maybe the output is not correct, but even then it concerns 
gcc and not ct-ng.

Greetings,

Erik.


>     -march=                               armv7-a
>     -mcpu=                                [default]
>     -mtune=                               cortex-a8
>
> As you can see, the resulting gcc doesn't have the target optimization
> for -mcpu that I configured.
>
> Shouldn't that correspond?
>
> I've been using ct-ng.1.20.0. Please see below for the complete
> defconfig file and the (almost) complete output of "*-gcc -Q
> --help=target".
>
> Thanks for your insight,
>
> Erik Leunissen.
> --
>
>  > cat defconfig
> CT_EXPERIMENTAL=y
> CT_LOCAL_TARBALLS_DIR="/mnt/local/heavy-duty/ct-ng/tarballs"
> CT_SAVE_TARBALLS=y
> CT_WORK_DIR="/mnt/local/heavy-duty/ct-ng/.build"
> CT_PREFIX_DIR="/mnt/local/heavy-duty/ct-ng/${CT_TARGET}/installdir"
> CT_PARALLEL_JOBS=4
> CT_LOG_EXTRA=y
> CT_ARCH_ARCH="armv7-a"
> CT_ARCH_CPU="cortex-a8"
> CT_ARCH_TUNE="cortex-a8"
> CT_ARCH_FPU="neon"
> CT_ARCH_FLOAT_HW=y
> CT_ARCH_arm=y
> CT_ARCH_ARM_TUPLE_USE_EABIHF=y
> CT_TARGET_VENDOR="vendor"
> CT_TARGET_ALIAS="arm-cortex_a8_neon-linux-gnueabihf"
> CT_KERNEL_linux=y
> CT_BINUTILS_V_2_22=y
> CT_BINUTILS_LINKER_LD_GOLD=y
> CT_BINUTILS_GOLD_THREADS=y
> CT_BINUTILS_LD_WRAPPER=y
> CT_BINUTILS_PLUGINS=y
> CT_LIBC_glibc=y
> CT_CC_LANG_CXX=y
> CT_DEBUG_dmalloc=y
> CT_DEBUG_duma=y
> CT_DEBUG_gdb=y
> # CT_GDB_CROSS_PYTHON is not set
> CT_GDB_NATIVE=y
> CT_GDB_NATIVE_STATIC=y
> CT_DEBUG_ltrace=y
> CT_DEBUG_strace=y
>
>  > ./*-gcc -Q --help=target
> The following options are target specific:
>    -mabi=                                aapcs-linux
>    -mabort-on-noreturn                   [disabled]
>    -mandroid                             [disabled]
>    -mapcs                                [disabled]
>    -mapcs-float                          [disabled]
>    -mapcs-frame                          [disabled]
>    -mapcs-reentrant                      [disabled]
>    -mapcs-stack-check                    [disabled]
>    -march=                               armv7-a
>    -marm                                 [enabled]
>    -mbig-endian                          [disabled]
>    -mbionic                              [disabled]
>    -mcallee-super-interworking           [disabled]
>    -mcaller-super-interworking           [disabled]
>    -mcpu=                                [default]
>    -mfix-cortex-m3-ldrd                  [enabled]
>    -mfloat-abi=                          hard
>    -mfp16-format=                        none
>    -mfpu=                                neon
>    -mglibc                               [enabled]
>    -mhard-float
>    -mlittle-endian                       [enabled]
>    -mlong-calls                          [disabled]
>    -mlra                                 [enabled]
>    -mneon-for-64bits                     [disabled]
>    -mnew-generic-costs                   [disabled]
>    -mold-rtx-costs                       [disabled]
>    -mpic-data-is-text-relative           [enabled]
>    -mpic-register=
>    -mpoke-function-name                  [disabled]
>    -mrestrict-it                         [enabled]
>    -msched-prolog                        [enabled]
>    -msingle-pic-base                     [disabled]
>    -mslow-flash-data                     [disabled]
>    -msoft-float
>    -mstructure-size-boundary=            0x20
>    -mthumb                               [disabled]
>    -mthumb-interwork                     [enabled]
>    -mtls-dialect=                        gnu
>    -mtp=                                 auto
>    -mtpcs-frame                          [disabled]
>    -mtpcs-leaf-frame                     [disabled]
>    -mtune=                               cortex-a8
>    -muclibc                              [disabled]
>    -munaligned-access                    [enabled]
>    -mvectorize-with-neon-double          [disabled]
>    -mvectorize-with-neon-quad            [enabled]
>    -mword-relocations                    [disabled]
>    -mwords-little-endian                 [disabled]
>
> [snipped the ensuing dump of configurable options]
>
> == end of message ==
>
> --
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