linux-kernel - [PATCH] x86/build: Move max-page-size option to LDFLAGS

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Message-Id: <20200722184334.3785418-1-nivedita@alum.mit.edu>
Date:   Wed, 22 Jul 2020 14:43:34 -0400
From:   Arvind Sankar <nivedita@...m.mit.edu>
To:     x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] x86/build: Move max-page-size option to LDFLAGS_vmlinux

This option is only required for vmlinux on 64-bit, to enforce 2MiB
alignment, so set it in LDFLAGS_vmlinux instead of KBUILD_LDFLAGS. Also
drop the ld-option check: this option was added in binutils-2.18 and all
the other places that use it already don't have the check.

This reduces the size of the intermediate ELF files
arch/x86/boot/setup.elf and arch/x86/realmode/rm/realmode.elf by about
2MiB each. The binary versions are unchanged.

Move the LDFLAGS settings to all be together and just after CFLAGS
settings are done.

Signed-off-by: Arvind Sankar <nivedita@...m.mit.edu>
---
 arch/x86/Makefile | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 00e378de8bc0..1e634d7ee6eb 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -47,10 +47,6 @@ export REALMODE_CFLAGS
 # e.g.: obj-y += foo_$(BITS).o
 export BITS
 
-ifdef CONFIG_X86_NEED_RELOCS
-        LDFLAGS_vmlinux := --emit-relocs --discard-none
-endif
-
 #
 # Prevent GCC from generating any FP code by mistake.
 #
@@ -177,17 +173,6 @@ ifeq ($(ACCUMULATE_OUTGOING_ARGS), 1)
 	KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args,)
 endif
 
-KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE)
-
-#
-# The 64-bit kernel must be aligned to 2MB.  Pass -z max-page-size=0x200000 to
-# the linker to force 2MB page size regardless of the default page size used
-# by the linker.
-#
-ifdef CONFIG_X86_64
-KBUILD_LDFLAGS += $(call ld-option, -z max-page-size=0x200000)
-endif
-
 # Workaround for a gcc prelease that unfortunately was shipped in a suse release
 KBUILD_CFLAGS += -Wno-sign-compare
 #
@@ -207,6 +192,23 @@ ifdef CONFIG_RETPOLINE
   endif
 endif
 
+KBUILD_LDFLAGS := -m elf_$(UTS_MACHINE)
+
+ifdef CONFIG_X86_NEED_RELOCS
+LDFLAGS_vmlinux := --emit-relocs --discard-none
+else
+LDFLAGS_vmlinux :=
+endif
+
+#
+# The 64-bit kernel must be aligned to 2MB.  Pass -z max-page-size=0x200000 to
+# the linker to force 2MB page size regardless of the default page size used
+# by the linker.
+#
+ifdef CONFIG_X86_64
+LDFLAGS_vmlinux += -z max-page-size=0x200000
+endif
+
 archscripts: scripts_basic
 	$(Q)$(MAKE) $(build)=arch/x86/tools relocs
 
-- 
2.26.2