linux-kernel - Re: [PATCH] x86: avoid warning for zero-filling .bss

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Message-ID: <adb36672-58cb-e290-9587-99e3ec6d9f0a@zytor.com>
Date:   Thu, 17 Nov 2016 16:07:47 -0800
From:   "H. Peter Anvin" <hpa@...or.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>, Arnd Bergmann <arnd@...db.de>
Cc:     x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Andy Lutomirski <luto@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: avoid warning for zero-filling .bss

On 11/17/16 14:44, Josh Poimboeuf wrote:
> On Thu, Nov 17, 2016 at 11:32:30PM +0100, Arnd Bergmann wrote:
>> On Thursday, November 17, 2016 3:02:48 PM CET Josh Poimboeuf wrote:
>>> On Wed, Nov 16, 2016 at 03:17:09PM +0100, Arnd Bergmann wrote:
>>>> The latest binutils are warning about a .fill directive with an explicit
>>>> value in a .bss section:
>>>>
>>>> arch/x86/kernel/head_32.S: Assembler messages:
>>>> arch/x86/kernel/head_32.S:677: Warning: ignoring fill value in section `.bss..page_aligned'
>>>> arch/x86/kernel/head_32.S:679: Warning: ignoring fill value in section `.bss..page_aligned'
>>>>
>>>> This comes from the 'ENTRY()' macro padding the space between the symbols
>>>> with 'nop'. Open-coding the .globl directive without the padding
>>>> avoids that warning.
>>>
>>> How is there space between the symbols?  Aren't they already aligned?
>>
>> My understanding is that they are aligned, it's just that gas complains
>> about the .align directive with a nonzero fill value.
> 
> Ah, I see now.  In that case your patch looks fine to me.
> 

Yes, ENTRY() is for code.

	-hpa