linux-kernel - Re: [PATCH 12/12] efi: make const array 'apple' static

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Date:   Fri, 9 Mar 2018 07:44:18 +0000
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     Joe Perches <joe@...ches.com>
Cc:     linux-efi@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Colin Ian King <colin.king@...onical.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 12/12] efi: make const array 'apple' static

On 9 March 2018 at 07:43, Ard Biesheuvel <ard.biesheuvel@...aro.org> wrote:
> On 8 March 2018 at 11:05, Joe Perches <joe@...ches.com> wrote:
>> On Thu, 2018-03-08 at 08:00 +0000, Ard Biesheuvel wrote:
>>> From: Colin Ian King <colin.king@...onical.com>
>>>
>>> Don't populate the const read-only array 'buf' on the stack but instead
>>> make it static. Makes the object code smaller by 64 bytes:
>>>
>>> Before:
>>>    text          data     bss     dec     hex filename
>>>    9264             1      16    9281    2441 arch/x86/boot/compressed/eboot.o
>>>
>>> After:
>>>    text          data     bss     dec     hex filename
>>>    9200             1      16    9217    2401 arch/x86/boot/compressed/eboot.o
>>>
>>> (gcc version 7.2.0 x86_64)
>>>
>>> Signed-off-by: Colin Ian King <colin.king@...onical.com>
>>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
>>> ---
>>>  arch/x86/boot/compressed/eboot.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
>>> index 886a9115af62..f2251c1c9853 100644
>>> --- a/arch/x86/boot/compressed/eboot.c
>>> +++ b/arch/x86/boot/compressed/eboot.c
>>> @@ -423,7 +423,7 @@ static void retrieve_apple_device_properties(struct boot_params *boot_params)
>>>
>>>  static void setup_quirks(struct boot_params *boot_params)
>>>  {
>>> -     efi_char16_t const apple[] = { 'A', 'p', 'p', 'l', 'e', 0 };
>>> +     static efi_char16_t const apple[] = { 'A', 'p', 'p', 'l', 'e', 0 };
>>
>> Perhaps
>>
>> static const efi_char16_t apple[] ...
>>
>> is better.
>>
>
> Why would that be any better? I have always found the 'const'
> placement after the type to be much clearer.
>
> const void *
> void const *
> void * const
>
> I.e., #2 and #3 are equivalent,

That would be #1 and #2, of course

> and so 'const' associates to the left
> not to the right, unless it is at the beginning.
>
> Personally, I don't mind either way, but saying it is 'better' is a stretch imo