pc-bios/s390-ccw: avoid floating point operations

Some gcc versions (e.g. Fedora 22 gcc 5.1.1) seem to use floating
point registers for spilling and filling of general purpose registers.
As the BIOS does not activate the AFP register setting of CR0 this can
cause data exception program checks.
Disallow floating point in the BIOS as a simple solution.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NJens Freimann <jfrei@linux.vnet.ibm.com>
Message-Id: <1443689387-34473-2-git-send-email-jfrei@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

pc-bios/s390-ccw/Makefile

@@ -10,7 +10,8 @@ $(call set-vpath, $(SRC_PATH)/pc-bios/s390-ccw)
 .PHONY : all clean build-all
 
 OBJECTS = start.o main.o bootmap.o sclp-ascii.o virtio.o
-CFLAGS += -fPIE -fno-stack-protector -ffreestanding -fno-delete-null-pointer-checks
+CFLAGS += -fPIE -fno-stack-protector -ffreestanding
+CFLAGS += -fno-delete-null-pointer-checks -msoft-float
 LDFLAGS += -Wl,-pie -nostdlib
 
 build-all: s390-ccw.img