linux-kernel - Re: [PATCH] m32r: add __ucmpdi2 to fix build failure

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Message-ID: <575A677C.1010507@gmail.com>
Date:	Fri, 10 Jun 2016 08:08:44 +0100
From:	Sudip Mukherjee <sudipm.mukherjee@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] m32r: add __ucmpdi2 to fix build failure

On Thursday 09 June 2016 11:16 PM, Andrew Morton wrote:
> On Thu,  9 Jun 2016 22:53:33 +0100 Sudip Mukherjee <sudipm.mukherjee@...il.com> wrote:
>
>> We are having build failure with m32r and the error message being:
>> ERROR: "__ucmpdi2" [lib/842/842_decompress.ko] undefined!
>> ERROR: "__ucmpdi2" [fs/btrfs/btrfs.ko] undefined!
>> ERROR: "__ucmpdi2" [drivers/scsi/sd_mod.ko] undefined!
>> ERROR: "__ucmpdi2" [drivers/media/i2c/adv7842.ko] undefined!
>> ERROR: "__ucmpdi2" [drivers/md/bcache/bcache.ko] undefined!
>> ERROR: "__ucmpdi2" [drivers/iio/imu/inv_mpu6050/inv-mpu6050.ko] undefined!
>>
>> __ucmpdi2 is introduced to m32r architecture taking example from other
>> architectures like h8300, microblaze, mips.
>>
>> --- a/arch/m32r/kernel/m32r_ksyms.c
>> +++ b/arch/m32r/kernel/m32r_ksyms.c
>> @@ -41,6 +41,9 @@ EXPORT_SYMBOL(cpu_data);
>>   EXPORT_SYMBOL(smp_flush_tlb_page);
>>   #endif
>>
>> +extern int __ucmpdi2(unsigned long long a, unsigned long long b);
>> +EXPORT_SYMBOL(__ucmpdi2);
>> +
>
> This would be neater.  Does it work?
>
>
> From: Andrew Morton <akpm@...ux-foundation.org>
> Subject: m32r-add-__ucmpdi2-to-fix-build-failure-fix
>
> avoid extern declaration in .c file
>
> Cc: Sudip Mukherjee <sudip.mukherjee@...ethink.co.uk>
> Cc: Sudip Mukherjee <sudipm.mukherjee@...il.com>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
>
> --- a/arch/m32r/kernel/m32r_ksyms.c~m32r-add-__ucmpdi2-to-fix-build-failure-fix
> +++ a/arch/m32r/kernel/m32r_ksyms.c
> @@ -41,7 +41,6 @@ EXPORT_SYMBOL(cpu_data);
>   EXPORT_SYMBOL(smp_flush_tlb_page);
>   #endif
>
> -extern int __ucmpdi2(unsigned long long a, unsigned long long b);
>   EXPORT_SYMBOL(__ucmpdi2);
>
>   /* compiler generated symbol */
> --- a/arch/m32r/lib/libgcc.h~m32r-add-__ucmpdi2-to-fix-build-failure-fix
> +++ a/arch/m32r/lib/libgcc.h
> @@ -22,3 +22,4 @@ typedef union {
>
>   #endif /* __ASM_LIBGCC_H */
>
> +extern int __ucmpdi2(unsigned long long a, unsigned long long b);
>


Nope.
In file included from ../include/linux/linkage.h:6:0,
                  from ../include/linux/kernel.h:6,
                  from ../include/linux/list.h:8,
                  from ../include/linux/module.h:9,
                  from ../arch/m32r/kernel/m32r_ksyms.c:1:
../arch/m32r/kernel/m32r_ksyms.c:44:15: error: '__ucmpdi2' undeclared 
here (not in a function)
  EXPORT_SYMBOL(__ucmpdi2);
                ^
../include/linux/export.h:57:16: note: in definition of macro 
'___EXPORT_SYMBOL'
   extern typeof(sym) sym;     \
                 ^
../arch/m32r/kernel/m32r_ksyms.c:44:1: note: in expansion of macro 
'EXPORT_SYMBOL'
  EXPORT_SYMBOL(__ucmpdi2);
  ^
make[2]: *** [arch/m32r/kernel/m32r_ksyms.o] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [arch/m32r/kernel] Error 2
make[1]: *** Waiting for unfinished jobs....

m32r_ksyms.c is not having any reference to the name. If you want to 
remove the extern from the C file then I think we should declare it in 
some header file and include that in the m32r_ksyms.c. And if that works 
then that can be applied to all the other arch also, as almost all of 
them have these externs in *_ksyms.c.

Regards
Sudip