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

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Date:   Wed, 11 Oct 2017 14:13:32 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Will Deacon <will.deacon@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Michal Marek <mmarek@...e.com>,
        Alexander Popov <alex.popov@...ux.com>,
        James Morse <james.morse@....com>,
        Linux Kernel Mailing List <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>
Subject: Re: [PATCH] arm64: remove unneeded copy to init_utsname()->machine

Hi,

On Wed, Oct 11, 2017 at 10:03:28PM +0900, Masahiro Yamada wrote:
> Hi arm64 maintainers,
> 
> Could you check this please?

This patch has been queued [1] in arm64's for-next/core branch [2], and
should be in v4.15.

Thanks,
Mark.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/commit/?h=for-next/core&id=c2f0b54f10b12620c57f6e31233589b704a00ed5
[2] https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/log/?h=for-next/core

> 2017-09-14 20:40 GMT+09:00 Masahiro Yamada <yamada.masahiro@...ionext.com>:
> > 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
> >
> 
> 
> 
> -- 
> Best Regards
> Masahiro Yamada