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[2/3] powerpc: allow compilation on cross-endian toolchain

Message ID 20161124200423.45c5ec87@roar.ozlabs.ibm.com (mailing list archive)
State Superseded
Headers show

Commit Message

Nicholas Piggin Nov. 24, 2016, 9:04 a.m. UTC 
On Thu, 24 Nov 2016 00:02:08 +1100
Nicholas Piggin <npiggin@gmail.com> wrote:

> GCC can compile with either endian, but the ABI version always
> defaults to the default endian. Alan Modra says:

Okay I was missing mcall-aixdesc, thanks again to Alan for pointing
it out.

This updated patch seems to do better, and it builds BE kernel with
powerpc64le-gcc, and LE with powerpc64-gcc here (I did see a link
failure but then couldn't reproduce it so it might have been a stale
file hanging around somewhere).


From: Nicholas Piggin <npiggin@gmail.com>
Date: Wed, 23 Nov 2016 17:27:39 +1100
Subject: [PATCH] powerpc: allow compilation on cross-endian toolchain

GCC can compile with either endian, but the ABI version always
defaults to the default endian. Alan Modra says:

  you need both -mbig and -mabi=elfv1 to make a powerpc64le gcc
  generate powerpc64 code

The opposite is true for powerpc64 when generating -mlittle it
requires -mabi=elfv2 to generate v2 ABI. This change adds ABI
annotations together with endianness. The kernel with ELFv2 ABI
also uses -mcall-aixdesc, but boot/ does not.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/Makefile      | 7 +++++++
 arch/powerpc/boot/Makefile | 1 +
 2 files changed, 8 insertions(+)

Comments

Michael Ellerman Nov. 26, 2016, 7:30 a.m. UTC | #1 
Nicholas Piggin <npiggin@gmail.com> writes:
> On Thu, 24 Nov 2016 00:02:08 +1100
> diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
> index 617dece..8828807 100644
> --- a/arch/powerpc/Makefile
> +++ b/arch/powerpc/Makefile
> @@ -73,13 +73,18 @@ MULTIPLEWORD	:= -mmultiple
>  endif
>  
>  cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mbig-endian)
> +cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mabi=elfv1)
> +cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mcall-aixdesc)

This blew up the world:

  http://kisskb.ellerman.id.au/kisskb/head/1ba4cb3d67e181bdc9a911d7be81f64e3d7597d2/

  Successful:	24% 63/258

I suspect you need to make -mcall-aixdesc 64-bit only.

cheers
diff mbox

Patch

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 617dece..8828807 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -73,13 +73,18 @@  MULTIPLEWORD	:= -mmultiple
 endif
 
 cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mbig-endian)
+cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mabi=elfv1)
+cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mcall-aixdesc)
 cflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mlittle-endian
+cflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mabi=elfv2
 ifneq ($(cc-name),clang)
   cflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mno-strict-align
 endif
 
 aflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mbig-endian)
+aflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mabi=elfv1)
 aflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mlittle-endian
+aflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mabi=elfv2
 
 ifeq ($(HAS_BIARCH),y)
 override AS	+= -a$(BITS)
@@ -113,7 +118,9 @@  ifeq ($(CONFIG_CPU_LITTLE_ENDIAN),y)
 CFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mabi=elfv2,$(call cc-option,-mcall-aixdesc))
 AFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mabi=elfv2)
 else
+CFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mabi=elfv1)
 CFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mcall-aixdesc)
+AFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mabi=elfv1)
 endif
 CFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mcmodel=medium,$(call cc-option,-mminimal-toc))
 CFLAGS-$(CONFIG_PPC64)	+= $(call cc-option,-mno-pointers-to-nested-functions)
diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile
index eae2dc8..1d50d41 100644
--- a/arch/powerpc/boot/Makefile
+++ b/arch/powerpc/boot/Makefile
@@ -33,6 +33,7 @@  BOOTCFLAGS	+= -m64
 endif
 ifdef CONFIG_CPU_BIG_ENDIAN
 BOOTCFLAGS	+= -mbig-endian
+BOOTCFLAGS	+= $(call cc-option,-mabi=elfv1)
 else
 BOOTCFLAGS	+= -mlittle-endian
 BOOTCFLAGS	+= $(call cc-option,-mabi=elfv2)