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arch/arm: VFP and Thumb1 are not compatible

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gcc will refuse to build with both --with-mode=thumb and --with-fpu=vfp,
with error messages during ./configure, like:

    checking for suffix of object files... configure: error: in `/home/ymor
    in/dev/buildroot/O/build/host-gcc-initial-4.9.3/build/arm-buildroot-lin
    ux-uclibcgnueabihf/libgcc':
    configure: error: cannot compute suffix of object files: cannot compile
    See `config.log' for more details.

And config.log informatively contains:

    sorry, unimplemented: Thumb-1 hard-float VFP ABI

This is an error message that comes deep from gcc source files.

If gcc says it does not support VFP with Thumb1, then let's disable that
combination in our menuconfig.

Prefer VFP over Thumb1, i.e. hide Thumb1 when we're not soft-float.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Gustavo Zacarias <gustavo@zacarias.com.ar>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
This commit is contained in:
Yann E. MORIN 2015-11-03 00:34:37 +01:00 committed by Thomas Petazzoni
parent 4f7f86fb1d
commit e4b1fa69cd
1 changed files with 6 additions and 0 deletions
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6
arch/Config.in.arm
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@ -377,12 +377,18 @@ config BR2_ARM_INSTRUCTIONS_ARM
config BR2_ARM_INSTRUCTIONS_THUMB
bool "Thumb"
depends on BR2_ARM_CPU_HAS_THUMB
# Thumb-1 and VFP are not compatible
depends on BR2_ARM_SOFT_FLOAT
help
This option instructions the compiler to generate Thumb
instructions, which allows to mix 16 bits instructions and
32 bits instructions. This generally provides a much smaller
compiled binary size.
comment "Thumb1 is not compatible with VFP"
depends on BR2_ARM_CPU_HAS_THUMB
depends on !BR2_ARM_SOFT_FLOAT
config BR2_ARM_INSTRUCTIONS_THUMB2
bool "Thumb2"
depends on BR2_ARM_CPU_HAS_THUMB2