linux-kernel - Re: Help with compiler warning

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Message-ID: <48B18361.6000305@lwfinger.net>
Date:	Sun, 24 Aug 2008 10:50:57 -0500
From:	Larry Finger <Larry.Finger@...inger.net>
To:	Benny Halevy <bhalevy@...asas.com>
CC:	LKML <linux-kernel@...r.kernel.org>,
	Dominik Brodowski <linux@...inikbrodowski.net>
Subject: Re: Help with compiler warning

Benny Halevy wrote:
> On Aug. 24, 2008, 18:29 +0300, Benny Halevy <bhalevy@...asas.com> wrote:
>> On Aug. 22, 2008, 4:36 +0300, Larry Finger <Larry.Finger@...inger.net> wrote:
>>> In drivers/pcmcia/cardbus.c, the following statement
>>>
>>>          memcpy_fromio(ptr, s->cb_cis_virt + addr, len);
>>>
>>> generates the warning
>>>
>>>    CC [M]  drivers/pcmcia/cardbus.o
>>> include/asm/io_32.h: In function ‘memcpy_fromio’:
>>> include/asm/io_32.h:151: warning: passing argument 2 of ‘__memcpy’ 
>>> discards qualifiers from pointer target type
>>>
>>> s->cb_cis_virt is "void __iomem" and addr is uint.
>>>
>>> What cast does argument 2 need to silence the warning?
>> memcpy_fromio takes a (const volatile void __iomem *) for the 
>> src address.
> 
> So the culprit could be the volatile qualifier...

Changing it to

memcpy_fromio(ptr, (const volatile void __iomem *)(s->cb_cis_virt + 
addr), len);

memcpy_fromio(ptr, (const volatile void __iomem *)s->cb_cis_virt + 
addr, len);

memcpy_fromio(ptr, (volatile void __iomem *)(s->cb_cis_virt + addr), len);

or

memcpy_fromio(ptr, (volatile void __iomem *)s->cb_cis_virt + addr, len);

makes no difference.

Thanks,

Larry
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