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authorAnton Blanchard <anton@samba.org>2012-11-26 17:41:08 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-01-10 17:00:31 +1100
commit1fbe9cf2598dae3bd464d860bd89c67b1ff8682b (patch)
treec07f1fe789777669466bc3077a5f0afa70cf83b6 /arch/powerpc/Makefile
parent5827d4165ac608d7c26fa68701391e80824ee5c9 (diff)
powerpc: Build kernel with -mcmodel=medium
Finally remove the two level TOC and build with -mcmodel=medium. Unfortunately we can't build modules with -mcmodel=medium due to the tricks the kernel module loader plays with percpu data: # -mcmodel=medium breaks modules because it uses 32bit offsets from # the TOC pointer to create pointers where possible. Pointers into the # percpu data area are created by this method. # # The kernel module loader relocates the percpu data section from the # original location (starting with 0xd...) to somewhere in the base # kernel percpu data space (starting with 0xc...). We need a full # 64bit relocation for this to work, hence -mcmodel=large. On older kernels we fall back to the two level TOC (-mminimal-toc) Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/Makefile')
-rw-r--r--arch/powerpc/Makefile19
1 files changed, 18 insertions, 1 deletions
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 78c2b024371a..31d8965e0847 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -67,7 +67,24 @@ LDFLAGS_vmlinux-y := -Bstatic
LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie
LDFLAGS_vmlinux := $(LDFLAGS_vmlinux-y)
-CFLAGS-$(CONFIG_PPC64) := -mminimal-toc -mtraceback=no -mcall-aixdesc
+ifeq ($(CONFIG_PPC64),y)
+ifeq ($(call cc-option-yn,-mcmodel=medium),y)
+ # -mcmodel=medium breaks modules because it uses 32bit offsets from
+ # the TOC pointer to create pointers where possible. Pointers into the
+ # percpu data area are created by this method.
+ #
+ # The kernel module loader relocates the percpu data section from the
+ # original location (starting with 0xd...) to somewhere in the base
+ # kernel percpu data space (starting with 0xc...). We need a full
+ # 64bit relocation for this to work, hence -mcmodel=large.
+ KBUILD_CFLAGS_MODULE += -mcmodel=large
+else
+ export NO_MINIMAL_TOC := -mno-minimal-toc
+endif
+endif
+
+CFLAGS-$(CONFIG_PPC64) := -mtraceback=no -mcall-aixdesc
+CFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mcmodel=medium,-mminimal-toc)
CFLAGS-$(CONFIG_PPC32) := -ffixed-r2 -mmultiple
CFLAGS-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=power7,-mtune=power4)