The -O2 optimization flag is passed via CFLAGS to the firmware Makefile,
but in netbook.mak, we've got some rules that only use QEMU_CFLAGS for
compiling the libc and libnet from SLOF, so these files get compiled
without optimization so far. Use CFLAGS here, too, to create faster
and smaller code.

We can additionally save some more bytes in the firmware images by compi-
ling the code with -fno-asynchronous-unwind-tables. This will omit some
ELF sections (used for stack unwinding for example) from the image that
we do not need in the firmware.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 pc-bios/s390-ccw/Makefile    | 1 +
 pc-bios/s390-ccw/netboot.mak | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/pc-bios/s390-ccw/Makefile b/pc-bios/s390-ccw/Makefile
index 439e3cc..1eb316b 100644
--- a/pc-bios/s390-ccw/Makefile
+++ b/pc-bios/s390-ccw/Makefile
@@ -15,6 +15,7 @@ OBJECTS = start.o main.o bootmap.o jump2ipl.o sclp.o menu.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 += -fno-asynchronous-unwind-tables
 QEMU_CFLAGS += $(call cc-option, $(QEMU_CFLAGS), -fno-stack-protector)
 LDFLAGS += -Wl,-pie -nostdlib
 
diff --git a/pc-bios/s390-ccw/netboot.mak b/pc-bios/s390-ccw/netboot.mak
index 8af0cfd..14e96b2 100644
--- a/pc-bios/s390-ccw/netboot.mak
+++ b/pc-bios/s390-ccw/netboot.mak
@@ -19,7 +19,7 @@ s390-netboot.img: s390-netboot.elf
 
 # libc files:
 
-LIBC_CFLAGS :=  $(QEMU_CFLAGS) $(LIBC_INC) $(LIBNET_INC)
+LIBC_CFLAGS :=  $(QEMU_CFLAGS) $(CFLAGS) $(LIBC_INC) $(LIBNET_INC)
 
 CTYPE_OBJS = isdigit.o isxdigit.o toupper.o
 %.o : $(SLOF_DIR)/lib/libc/ctype/%.c
@@ -52,7 +52,7 @@ libc.a: $(LIBCOBJS)
 
 LIBNETOBJS := args.o dhcp.o dns.o icmpv6.o ipv6.o tcp.o udp.o bootp.o \
 	      dhcpv6.o ethernet.o ipv4.o ndp.o tftp.o pxelinux.o
-LIBNETCFLAGS := $(QEMU_CFLAGS) -DDHCPARCH=0x1F $(LIBC_INC) $(LIBNET_INC)
+LIBNETCFLAGS := $(QEMU_CFLAGS) $(CFLAGS) -DDHCPARCH=0x1F $(LIBC_INC) $(LIBNET_INC)
 
 %.o : $(SLOF_DIR)/lib/libnet/%.c
 	$(call quiet-command,$(CC) $(LIBNETCFLAGS) -c -o $@ $<,"CC","$(TARGET_DIR)$@")
-- 
1.8.3.1

On 06/14/2018 03:46 PM, Thomas Huth wrote:
> The -O2 optimization flag is passed via CFLAGS to the firmware Makefile,
> but in netbook.mak, we've got some rules that only use QEMU_CFLAGS for
> compiling the libc and libnet from SLOF, so these files get compiled
> without optimization so far. Use CFLAGS here, too, to create faster
> and smaller code.
> 
> We can additionally save some more bytes in the firmware images by compi-
> ling the code with -fno-asynchronous-unwind-tables. This will omit some
> ELF sections (used for stack unwinding for example) from the image that
> we do not need in the firmware.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>


> ---
>  pc-bios/s390-ccw/Makefile    | 1 +
>  pc-bios/s390-ccw/netboot.mak | 4 ++--
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/pc-bios/s390-ccw/Makefile b/pc-bios/s390-ccw/Makefile
> index 439e3cc..1eb316b 100644
> --- a/pc-bios/s390-ccw/Makefile
> +++ b/pc-bios/s390-ccw/Makefile
> @@ -15,6 +15,7 @@ OBJECTS = start.o main.o bootmap.o jump2ipl.o sclp.o menu.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 += -fno-asynchronous-unwind-tables
>  QEMU_CFLAGS += $(call cc-option, $(QEMU_CFLAGS), -fno-stack-protector)
>  LDFLAGS += -Wl,-pie -nostdlib
>  
> diff --git a/pc-bios/s390-ccw/netboot.mak b/pc-bios/s390-ccw/netboot.mak
> index 8af0cfd..14e96b2 100644
> --- a/pc-bios/s390-ccw/netboot.mak
> +++ b/pc-bios/s390-ccw/netboot.mak
> @@ -19,7 +19,7 @@ s390-netboot.img: s390-netboot.elf
>  
>  # libc files:
>  
> -LIBC_CFLAGS :=  $(QEMU_CFLAGS) $(LIBC_INC) $(LIBNET_INC)
> +LIBC_CFLAGS :=  $(QEMU_CFLAGS) $(CFLAGS) $(LIBC_INC) $(LIBNET_INC)
>  
>  CTYPE_OBJS = isdigit.o isxdigit.o toupper.o
>  %.o : $(SLOF_DIR)/lib/libc/ctype/%.c
> @@ -52,7 +52,7 @@ libc.a: $(LIBCOBJS)
>  
>  LIBNETOBJS := args.o dhcp.o dns.o icmpv6.o ipv6.o tcp.o udp.o bootp.o \
>  	      dhcpv6.o ethernet.o ipv4.o ndp.o tftp.o pxelinux.o
> -LIBNETCFLAGS := $(QEMU_CFLAGS) -DDHCPARCH=0x1F $(LIBC_INC) $(LIBNET_INC)
> +LIBNETCFLAGS := $(QEMU_CFLAGS) $(CFLAGS) -DDHCPARCH=0x1F $(LIBC_INC) $(LIBNET_INC)
>  
>  %.o : $(SLOF_DIR)/lib/libnet/%.c
>  	$(call quiet-command,$(CC) $(LIBNETCFLAGS) -c -o $@ $<,"CC","$(TARGET_DIR)$@")
>