linux-kernel - Re: drivers/gpu/drm/radeon/radeon_test.c:45: undefined reference to `_

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Message-ID: <alpine.LNX.2.01.0912191405460.12202@filesrv1.baby-dragons.com>
Date:	Sat, 19 Dec 2009 16:02:02 -0900 (AKST)
From:	"Mr. James W. Laferriere" <babydr@...y-dragons.com>
To:	Dave Hylands <dhylands@...il.com>
cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	linux-fbdev@...r.kernel.org,
	Linux Kernel Maillist <linux-kernel@...r.kernel.org>
Subject: Re: drivers/gpu/drm/radeon/radeon_test.c:45: undefined reference to
  `__udivdi3'

 	Hello Dave ,

On Sat, 19 Dec 2009, Dave Hylands wrote:
> Hi Jim,
> On Fri, Dec 18, 2009 at 12:54 PM, Mr. James W. Laferriere
> <babydr@...y-dragons.com> wrote:
>>        Hello Benjamin ,  I am not having a good time compiling 2.6.32.1 .
>> First RCU 'inline' difficulties then fusion-mpt 'inline' difficulty ,  Now
>> this .
>>        This one is not a simple as removing 'inline' from a statement .
>>        Would you please look into this ?  Anything else you need please just
>> ask .
>>        Please cc: me as I am not subscribed to linux-fbdev .
>>
>>                Tia ,  JimL
>>
> ...snip...
>> drivers/built-in.o(.text+0x11345a): In function `radeon_test_moves':
>> drivers/gpu/drm/radeon/radeon_test.c:45: undefined reference to `__udivdi3'
>> make: *** [.tmp_vmlinux1] Error 1
>
> __udivdi3 is a gcc helper function used to do 64-bit division. This
> form of 64-bit division is not supported from within the kernel (which
> is why you get the undefined symbol).
>
> There is <asm/div64.h> which contains a macro called do_div which can
> perform a 64-bit dvision by a 32-bit divisor.
 	Thank you ,  For replying .  Now I being a kernel level nothing ,  How 
does this help me get past the 'ld' time undefined reference ?  So we can have 
a kernel build complete (hopefully) successfully .

 	I've another ? as well how is it that the drm/radeon_test.c is using 
(well at least referencing) a non-kernel symbol ?  That alone is rather 
interesting .

 	But all I had to do is Disable DRM in the kernel .  Since this system is 
a remote device without a real need for DRI/DRM support that should cure my 
problem .  But someone else is going to need that support & I am sure they'll 
hit that same bug .

 		Tia ,  JimL
-- 
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| James   W.   Laferriere | System    Techniques | Give me VMS     |
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