[Qemu-devel] [PATCH] pc-bios/s390-ccw: build s390 bios with -fno-zero-initialized-in-bss

[Christian Borntraeger]

The QEMU ELF loader does not initialize the bss segment. This has
triggered several bugs in the past, e.g. see commit 5d739a4787a5
("s390-ccw.img: Fix sporadic errors with ccw boot image - initialize
css").

Instead of fixing these things one-by-one we can build the BIOS
with -fno-zero-initialized-in-bss. This will move the zero variables
also into the data segment, which is then part of a LOAD section.

Reported-by: Thomas Huth <address@hidden>
Signed-off-by: Christian Borntraeger <address@hidden>
---
 pc-bios/s390-ccw/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pc-bios/s390-ccw/Makefile b/pc-bios/s390-ccw/Makefile
index 6d0c2ee..2687590 100644
--- a/pc-bios/s390-ccw/Makefile
+++ b/pc-bios/s390-ccw/Makefile
@@ -12,7 +12,7 @@ $(call set-vpath, $(SRC_PATH)/pc-bios/s390-ccw)
 OBJECTS = start.o main.o bootmap.o sclp.o virtio.o virtio-scsi.o 
virtio-blkdev.o
 QEMU_CFLAGS := $(filter -W%, $(QEMU_CFLAGS))
 QEMU_CFLAGS += -ffreestanding -fno-delete-null-pointer-checks -msoft-float
-QEMU_CFLAGS += -march=z900 -fPIE -fno-strict-aliasing
+QEMU_CFLAGS += -march=z900 -fPIE -fno-strict-aliasing 
-fno-zero-initialized-in-bss
 QEMU_CFLAGS += $(call cc-option, $(QEMU_CFLAGS), -fno-stack-protector)
 LDFLAGS += -Wl,-pie -nostdlib
 
-- 
2.9.4