linux-kernel - [PATCH] arm64: remove unneeded copy to init

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Date:   Thu, 14 Sep 2017 20:40:04 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     linux-arm-kernel@...ts.infradead.org,
        Will Deacon <will.deacon@....com>,
        Catalin Marinas <catalin.marinas@....com>
Cc:     Michal Marek <mmarek@...e.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Alexander Popov <alex.popov@...ux.com>,
        James Morse <james.morse@....com>,
        linux-kernel@...r.kernel.org,
        AKASHI Takahiro <takahiro.akashi@...aro.org>,
        Laura Abbott <labbott@...hat.com>,
        Ingo Molnar <mingo@...nel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Mark Rutland <mark.rutland@....com>
Subject: [PATCH] arm64: remove unneeded copy to init_utsname()->machine

As you see in init/version.c, init_uts_ns.name.machine is initially
set to UTS_MACHINE.  There is no point to copy the same string.

I dug the git history to figure out why this line is here.  My best
guess is like this:

 - This line has been around here since the initial support of arm64
   by commit 9703d9d7f77c ("arm64: Kernel booting and initialisation").
   If ARCH (=arm64) and UTS_MACHINE (=aarch64) do not match,
   arch/$(ARCH)/Makefile is supposed to override UTS_MACHINE, but the
   initial version of arch/arm64/Makefile missed to do that.  Instead,
   the boot code copied "aarch64" to init_utsname()->machine.

 - Commit 94ed1f2cb5d4 ("arm64: setup: report ELF_PLATFORM as the
   machine for utsname") replaced "aarch64" with ELF_PLATFORM to
   make "uname" to reflect the endianness.

 - ELF_PLATFORM does not help to provide the UTS machine name to rpm
   target, so commit cfa88c79462d ("arm64: Set UTS_MACHINE in the
   Makefile") fixed it.  The commit simply replaced ELF_PLATFORM with
   UTS_MACHINE, but missed the fact the string copy itself is no longer
   needed.

Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
---

 arch/arm64/kernel/Makefile | 2 --
 arch/arm64/kernel/setup.c  | 2 --
 2 files changed, 4 deletions(-)

diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index f2b4e81..29764d7 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -10,8 +10,6 @@ CFLAGS_REMOVE_ftrace.o = -pg
 CFLAGS_REMOVE_insn.o = -pg
 CFLAGS_REMOVE_return_address.o = -pg
 
-CFLAGS_setup.o = -DUTS_MACHINE='"$(UTS_MACHINE)"'
-
 # Object file lists.
 arm64-obj-y		:= debug-monitors.o entry.o irq.o fpsimd.o		\
 			   entry-fpsimd.o process.o ptrace.o setup.o signal.o	\
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index d4b7405..b2fdb59 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -23,7 +23,6 @@
 #include <linux/stddef.h>
 #include <linux/ioport.h>
 #include <linux/delay.h>
-#include <linux/utsname.h>
 #include <linux/initrd.h>
 #include <linux/console.h>
 #include <linux/cache.h>
@@ -246,7 +245,6 @@ void __init setup_arch(char **cmdline_p)
 {
 	pr_info("Boot CPU: AArch64 Processor [%08x]\n", read_cpuid_id());
 
-	sprintf(init_utsname()->machine, UTS_MACHINE);
 	init_mm.start_code = (unsigned long) _text;
 	init_mm.end_code   = (unsigned long) _etext;
 	init_mm.end_data   = (unsigned long) _edata;
-- 
2.7.4