Re: new_build on ubuntu (dvbdev.c)

[Mauro Carvalho Chehab <maurochehab@gmail.com>]

Em 14-11-2010 10:12, Andy Walls escreveu:
> On Sun, 2010-11-14 at 20:26 +1100, Vincent McIntyre wrote:
>> On 11/14/10, Andy Walls <awalls@md.metrocast.net> wrote:
>>> On Sun, 2010-11-14 at 09:08 +1100, Vincent McIntyre wrote:
> 
> 
>>> noop_llseek() is a newer kernl function that provided a trivial llseek()
>>> implmenetation for drivers that don't support llseek() but still want to
>>> provide a successful return code:
>>>
>>> http://lkml.org/lkml/2010/4/9/193
>>> http://lkml.org/lkml/2010/4/9/184
>>>
>> Thanks for explaining this.

I've added several patches for the new-build today, in order to make it compile
against older kernels. I tested compilation here with both RHEL6 (2.6.32) and
Fedora 14 (2.6.35) and compilation is working fine. Didn't test the drivers.
I'm not sure if the remote controller will properly work with my quick backport.

>> First dumb question - (I'll try to minimise these)
>>
>>  * Inspection of the patches new_build/backports shows all the patches
>> are to things in the v4l/ tree
>>  * Yet the patch you pointed to is to fs/read_write.c and include/linux/fs.h
>>
>> So my question: should this function be implemented as a patch to
>> files outside the v4l/ tree
> 
> I'm not sure, I haven't looked at the build system.  I'm guessing no.
> 
> The build system *should* be using the kernel include files from your
> distribution.  Patching up fs.h in the git tree may not have any effect,
> and patching up fs/read_write.c in the git tree certainly won't have any
> effect.
> 
> You also don't want to muck with your installed kernel files.

The patches generally reverse-apply some upstream change. Andy's approach
could be done via compat.h. I opted to just backport the upstream patch.

Anyway, there were other problems on it, due to other API changes, and to
the move of the rc-core from .../IR to .../rc directory.

I opted to simplify the backports, avoiding to duplicate the same patch on several
different directories.

>> or as additional .c and .h files within the v4l top level. I guess the
>> latter would then need to be #included in a bunch of v4l files. I'm
>> mainly unsure of the convention here.
> 
> 1. A simple, stupid patch would just a statically defined, non-inline
> noop_llseek() function in each affected .c file.
> 
> In this particular case I'm not sure adding a special .h file, a new .c
> file, a way to build the new .c file, and a bunch of #include's is worth
> it.
> 
> or
> 
> 2. I suppose you could have a patch add a .h file that defined a
> non-inline static noop_llseek() function and just #include that where
> needed.  
> 
> or
> 
> 3.  You could just add
> 
> 	#define noop_llseek	NULL
> 
> instead of a real function in either of 1 or 2 above.
> 
>> I checked the mkrufky tree mentioned in README.patches but that didn't help.
>> I also checked the mercurial tree and could not find any backport of
>> noop_llseek,
>> but I may have missed something.
>>
>> The consumers of the function appear to be:
>> $ find v4l -exec grep -li noop_llseek {} \;
>> v4l/dvb_frontend.c
>> v4l/lirc_imon.c
>> v4l/lirc_dev.c
>> v4l/lirc_it87.c
>> v4l/imon.c
>> v4l/dvb_ca_en50221.c
>> v4l/dvb_net.c
>> v4l/dvbdev.c
>> v4l/lirc_sasem.c
>> v4l/av7110_av.c
>> v4l/av7110.c
>> v4l/av7110_ir.c
>> v4l/dst_ca.c
>> v4l/firedtv-ci.c
> 
> Regards,
> Andy
> 
> --
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