linux-kernel - Re: [PATCH] arch: metag: lib: add "umoddi3.S" file for _

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Message-ID: <52B419DE.8050706@gmail.com>
Date:	Fri, 20 Dec 2013 18:20:14 +0800
From:	Chen Gang <gang.chen.5i5j@...il.com>
To:	James Hogan <james.hogan@...tec.com>
CC:	rostedt@...dmis.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-metag@...r.kernel.org
Subject: Re: [PATCH] arch: metag: lib: add "umoddi3.S" file for __umoddi3()

On 12/20/2013 05:30 PM, James Hogan wrote:
> On 20/12/13 01:44, Chen Gang wrote:
>> On 12/19/2013 09:47 PM, James Hogan wrote:
>>> No, I believe there shouldn't be any use of the C 64bit division/modulo
>>> operations in generic kernel code in the first place, so like I said
>>> before the code in question should be fixed to use the proper functions
>>> in <linux/math64.h>.
>>>
>>
>> OK, thanks, your idea is one of fix ways.
>>
>> Hmm... for me, it is still not a bad idea to add "__umoddi3" to metag.
> 
> NAK
> 
> Please read this:
> http://yarchive.net/comp/linux/64bit_divide.html
> 

OK, thanks, that sounds reasonable to me. For kernel, we really need
treat it carefully.

Hmm... but do you know why we need some 64-bit functions which are
implemented under "arch/metag/lib/*.S"? can we use <linux/math64.h>
instead of them? (e.g 64-bit '/').

And for me, 64-bit '/' and '%' are related operations, if provide one,
we also need provide the other (or neither of them are provided).


Thanks.
-- 
Chen Gang

Open, share and attitude like air, water and life which God blessed
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