[PATCH u-boot] powerpc/mpc85xx: Improve disabling of SPE instructions

[PATCH u-boot] powerpc/mpc85xx: Improve disabling of SPE instructions

[Pali Rohár]

Specifying -mspe=no also disables usage of SPE instructions. It is
documented in "[PATCH,rs6000] make -mno-spe work as expected" email:
http://gcc.gnu.org/ml/gcc-patches/2008-04/msg00311.html

So replace -mspe=yes by -mspe=no, so make it clear that u-boot has to be
compiled without SPE instructions.

Linux kernel contains following Makefile code to achieve it:

    # No SPE instruction when building kernel
    # (We use all available options to help semi-broken compilers)
    KBUILD_CFLAGS += $(call cc-option,-mno-spe)
    KBUILD_CFLAGS += $(call cc-option,-mspe=no)

Do same for U-Boot.

Signed-off-by: Pali Rohár <pali@kernel.org>
---
 arch/powerpc/cpu/mpc85xx/config.mk | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/cpu/mpc85xx/config.mk b/arch/powerpc/cpu/mpc85xx/config.mk
index b6b5d2053aea..482bb90cb120 100644
--- a/arch/powerpc/cpu/mpc85xx/config.mk
+++ b/arch/powerpc/cpu/mpc85xx/config.mk
@@ -6,11 +6,12 @@
 PLATFORM_CPPFLAGS += -msoft-float -mno-string
 PLATFORM_RELFLAGS += -msingle-pic-base -fno-jump-tables
 
-# -mspe=yes is needed to have -mno-spe accepted by a buggy GCC;
+# No SPE instruction when building u-boot
+# (We use all available options to help semi-broken compilers)
 # see "[PATCH,rs6000] make -mno-spe work as expected" on
 # http://gcc.gnu.org/ml/gcc-patches/2008-04/msg00311.html
-PLATFORM_CPPFLAGS += $(call cc-option,-mspe=yes) \
-		   $(call cc-option,-mno-spe)
+PLATFORM_CPPFLAGS += $(call cc-option,-mno-spe) \
+		     $(call cc-option,-mspe=no)
 
 ifdef CONFIG_E6500
 PLATFORM_CPPFLAGS += -mcpu=e6500
-- 
2.20.1

Re: [PATCH u-boot] powerpc/mpc85xx: Improve disabling of SPE instructions

[Tom Rini]

[-- Attachment #1: Type: text/plain, Size: 802 bytes --]

On Sun, Dec 11, 2022 at 03:14:59PM +0100, Pali Rohár wrote:

> Specifying -mspe=no also disables usage of SPE instructions. It is
> documented in "[PATCH,rs6000] make -mno-spe work as expected" email:
> http://gcc.gnu.org/ml/gcc-patches/2008-04/msg00311.html
> 
> So replace -mspe=yes by -mspe=no, so make it clear that u-boot has to be
> compiled without SPE instructions.
> 
> Linux kernel contains following Makefile code to achieve it:
> 
>     # No SPE instruction when building kernel
>     # (We use all available options to help semi-broken compilers)
>     KBUILD_CFLAGS += $(call cc-option,-mno-spe)
>     KBUILD_CFLAGS += $(call cc-option,-mspe=no)
> 
> Do same for U-Boot.
> 
> Signed-off-by: Pali Rohár <pali@kernel.org>

Applied to u-boot/master, thanks!

-- 
Tom

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 659 bytes --]