NetCube-Systems-Austria/kumquat-buildroot
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Revert "configs/bananapi_m1: use NEON+VFPv4 as FPU strategy"

Browse Source 
The gcc man page states that specifying Neon as part of the fpu setting
has no effect, unless the -funsafe-math-optimizations is also specified,
because Neon is not compliant with IEEE 754:
```
    If the selected floating-point hardware includes the NEON extension
    (e.g. -mfpu=neon), note that floating-point operations are not
    generated by GCC's auto-vectorization pass unless
    -funsafe-math-optimizations is also specified. This is because NEON
    hardware does not fully implement the IEEE 754 standard for
    floating-point arithmetic (in particular denormal values are treated
    as zero), so the use of NEON instructions may lead to a loss of
    precision.
```

-funsafe-math-optimizations must be explictly specified per package to
really use NEON as FPU, but it's something that is left to the user as
well as setting BR2_ARM_FPU_NEON_VFPV4. This way the default
BR2_ARM_FPU_VFPV4D16 is used as previously. So let's revert the
offending patch.

This reverts commit aaced92e8c.

Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
This commit is contained in:
Giulio Benetti 2022-08-15 17:48:54 +02:00 committed by Yann E. MORIN
parent d5c1e67d3a
commit 25ecee3f17
1 changed files with 0 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
configs/bananapi_m1_defconfig
View File

@ -1,6 +1,5 @@
BR2_arm=y
BR2_cortex_a7=y
BR2_ARM_FPU_NEON_VFPV4=y
BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_4_18=y
BR2_TARGET_GENERIC_ISSUE="Welcome to Bananapi M1"
BR2_ROOTFS_POST_IMAGE_SCRIPT="support/scripts/genimage.sh"