linux-kernel - [tip:x86/build] x86, powerpc: Remove -funit-at-a-time compiler option entirely

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Message-ID: <tip-63fea0af43af5beb3779fd2cae078d5d77b4bb11@git.kernel.org>
Date:   Sun, 9 Dec 2018 03:07:37 -0800
From:   tip-bot for Masahiro Yamada <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     bp@...e.de, paulus@...ba.org, hpa@...or.com, mpe@...erman.id.au,
        tglx@...utronix.de, yamada.masahiro@...ionext.com,
        mingo@...nel.org, richard@...ma-star.at, x86@...nel.org,
        benh@...nel.crashing.org, linux-kernel@...r.kernel.org
Subject: [tip:x86/build] x86, powerpc: Remove -funit-at-a-time compiler
 option entirely

Commit-ID:  63fea0af43af5beb3779fd2cae078d5d77b4bb11
Gitweb:     https://git.kernel.org/tip/63fea0af43af5beb3779fd2cae078d5d77b4bb11
Author:     Masahiro Yamada <yamada.masahiro@...ionext.com>
AuthorDate: Mon, 12 Nov 2018 11:35:20 +0900
Committer:  Borislav Petkov <bp@...e.de>
CommitDate: Sun, 9 Dec 2018 11:55:32 +0100

x86, powerpc: Remove -funit-at-a-time compiler option entirely

GCC 4.6 manual says:

  -funit-at-a-time
    This option is left for compatibility reasons. -funit-at-a-time has
    no effect, while -fno-unit-at-a-time implies -fno-toplevel-reorder
    and -fno-section-anchors. Enabled by default.

Remove it.

Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Acked-by: Ingo Molnar <mingo@...nel.org>
Acked-by: Michael Ellerman <mpe@...erman.id.au>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Richard Weinberger <richard@...ma-star.at>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linuxppc-dev@...ts.ozlabs.org
Cc: x86-ml <x86@...nel.org>
Link: https://lkml.kernel.org/r/1541990120-9643-3-git-send-email-yamada.masahiro@socionext.com
---
 arch/powerpc/Makefile | 4 ----
 arch/x86/Makefile     | 4 ----
 arch/x86/Makefile.um  | 5 -----
 3 files changed, 13 deletions(-)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 8a2ce14d68d0..854199c9ab7e 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -228,10 +228,6 @@ KBUILD_CFLAGS += $(call cc-option,-mno-vsx)
 KBUILD_CFLAGS += $(call cc-option,-mno-spe)
 KBUILD_CFLAGS += $(call cc-option,-mspe=no)
 
-# Enable unit-at-a-time mode when possible. It shrinks the
-# kernel considerably.
-KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)
-
 # FIXME: the module load should be taught about the additional relocs
 # generated by this.
 # revert to pre-gcc-4.4 behaviour of .eh_frame
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index f5d7f4134524..58d82e9dc36d 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -130,10 +130,6 @@ else
 
         KBUILD_CFLAGS += -mno-red-zone
         KBUILD_CFLAGS += -mcmodel=kernel
-
-        # -funit-at-a-time shrinks the kernel .text considerably
-        # unfortunately it makes reading oopses harder.
-        KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)
 endif
 
 ifdef CONFIG_X86_X32
diff --git a/arch/x86/Makefile.um b/arch/x86/Makefile.um
index 577976b7d1f8..1db7913795f5 100644
--- a/arch/x86/Makefile.um
+++ b/arch/x86/Makefile.um
@@ -26,9 +26,6 @@ cflags-y += $(call cc-option,-mpreferred-stack-boundary=2)
 # an unresolved reference.
 cflags-y += -ffreestanding
 
-# gcc 4.3.0 needs -funit-at-a-time for extern inline functions.
-KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)
-
 KBUILD_CFLAGS += $(cflags-y)
 
 else
@@ -50,6 +47,4 @@ ELF_FORMAT := elf64-x86-64
 LINK-$(CONFIG_LD_SCRIPT_DYN) += -Wl,-rpath,/lib64
 LINK-y += -m64
 
-# Do unit-at-a-time unconditionally on x86_64, following the host
-KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)
 endif