[OpenWrt-Devel] [PATCH] mvebu, tegra: make CPU subtype default to vfp3-d16

[Petr Štetiar]

Armada 370 and Tegra2 processors have only 16 double-precision
registers. The change introduced by commit 8dcc1087602e ("toolchain:
ARM: Fix toolchain compilation for gcc 8.x") switched accidentally the
toolchain for mvebu cortexa9 subtarget to cpu type with 32
double-precision registers.

This stems from gcc defaults which assume "vfpv3-d32" if only "vfpv3" as
mfpu is specified. That change resulted in unusable image, in which
kernel will kill userspace as soon as it causing "Illegal instruction".

In order to fix those issues Tomas in commit 2d61f8821c7c ("mvebu:
cortexa9: correct cpu subtype") and commit 43d1d8851062 ("tegra: correct
cpu subtype") changed the CPU subtype to explicit vfpv3-d16 which fixed
the above mentioned issue, but on the other end it has resulted in the
need of building packages for this new CPU subtype which is not wanted
due to the increased infrastructure costs, like disk space and
additional build time which is huge for packages feed.

So lets just take a step back and make the vfp3-d16 explicit again.

Cc: Tomasz Maciej Nowak <tomek_n at o2.pl>
Cc: Christian Lamparter <chunkeey at gmail.com>
Reported-by: Paul Spooren <mail at aparcar.org>
Fixes: 43d1d8851062 ("tegra: correct cpu subtype")
Fixes: 2d61f8821c7c ("mvebu: cortexa9: correct cpu subtype")
Fixes: 8dcc1087602e ("toolchain: ARM: Fix toolchain compilation for gcc 8.x")
Signed-off-by: Petr Štetiar <ynezz at true.cz>
---
 include/target.mk                     | 3 +++
 target/linux/mvebu/cortexa9/target.mk | 2 +-
 target/linux/tegra/Makefile           | 2 +-
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/include/target.mk b/include/target.mk
index 9bd4c14936c1..94ea1a9e0001 100644
--- a/include/target.mk
+++ b/include/target.mk
@@ -179,6 +179,9 @@ ifeq ($(DUMP),1)
   endif
   ifneq ($(findstring arm,$(ARCH)),)
     CPU_TYPE ?= xscale
+    ifeq ($(CONFIG_SOFT_FLOAT),)
+      CPU_CFLAGS_vfpv3 = -mfpu=vfpv3-d16
+    endif
   endif
   ifeq ($(ARCH),powerpc)
     CPU_CFLAGS_603e:=-mcpu=603e
diff --git a/target/linux/mvebu/cortexa9/target.mk b/target/linux/mvebu/cortexa9/target.mk
index cdd4d86e4936..2a75599bc9a3 100644
--- a/target/linux/mvebu/cortexa9/target.mk
+++ b/target/linux/mvebu/cortexa9/target.mk
@@ -10,5 +10,5 @@ include $(TOPDIR)/rules.mk
 ARCH:=arm
 BOARDNAME:=Marvell Armada 37x/38x/XP
 CPU_TYPE:=cortex-a9
-CPU_SUBTYPE:=vfpv3-d16
+CPU_SUBTYPE:=vfpv3
 KERNELNAME:=zImage dtbs
diff --git a/target/linux/tegra/Makefile b/target/linux/tegra/Makefile
index 5dd4d439849e..0b48fc16baa2 100644
--- a/target/linux/tegra/Makefile
+++ b/target/linux/tegra/Makefile
@@ -11,7 +11,7 @@ BOARD := tegra
 BOARDNAME := NVIDIA Tegra
 FEATURES := audio boot-part display ext4 fpu gpio pci pcie rootfs-part rtc squashfs usb
 CPU_TYPE := cortex-a9
-CPU_SUBTYPE := vfpv3-d16
+CPU_SUBTYPE := vfpv3
 
 KERNEL_PATCHVER := 5.4
 KERNEL_TESTING_PATCHVER := 5.4

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