Re: [ANNOUNCE] git tree repositories & libv4l

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 02/24/2010 01:58 AM, Mauro Carvalho Chehab wrote:
> Hans de Goede wrote:
>> Hi,
>>
>> On 02/23/2010 04:37 PM, Mauro Carvalho Chehab wrote:
>>> Hans de Goede wrote:
>>>
>>>> Ok, so this will give me a local tree, how do I get this onto
>>>> linuxtv.org ?
>>>
>>> I added it. In thesis, it is open for commit to you, me, hverkuil and
>>> dougsland.
>>>
>>
>> I see good, thanks! Can someone (Douglas ?) with better hg / git powers
>> then me please
>> somehow import all the libv4l changes from:
>> http://linuxtv.org/hg/~hgoede/libv4l
>
> Ok, I added there. The procedure were simple: I ran Brandon script again,
> but after pulling from your tree. Then, I used git format-patch to generate
> a quilt series, and used git quiltimport on the correct -git tree.
>

Thanks!


>> Once that is done I'll retire my own tree, and move all my userspace
>> work to
>> the git tree.
>>
>> For starters I plan to create / modify Makefiles so that everything will
>> build
>> out of the box, and has proper make install targets which can be used by
>> distro's
>>
>> So:
>> -proper honoring of CFLAGS
>> -work with standard (and possibly somewhat older kernel headers)
>> -honor DESTDIR, PREFIX and LIBDIR when doing make install
>
> The better here is to have the latest kernel headers copied on the tree.
> This way, it is possible to compile libv4l2 with an older kernel version and
> later upgrade the kernel, if needed, or to use a fast machine to compile
> it, and then use it on another machine.
>

If possible I would like to avoid this, afaik no other userspace utility packages
are doing this.

Where necessary libv4l currently has code snippets like:

#ifndef V4L2_PIX_FMT_SPCA501
#define V4L2_PIX_FMT_SPCA501 v4l2_fourcc('S','5','0','1') /* YUYV per line */
#endif

So libv4l (in its current state) will already compile fine with older kernel
headers. I expect that the other utilities will not need a lot of
recent kernel ABI. So for now I would like to try and extend the above approach
to the other utilities.

The reason for this is that I want to avoid carrying a copy of a dir from some
other tree, with all getting stale and needing sync all the time issues that
come with that, not to mention chicken and egg problems in the case of
new formats which simultaneously  need to be added to both libv4l and the kernel.

For example often I add support for V4L2_PIX_FMT_NEW_FOO to libv4l, before it
hits any official v4l-dvb kernel tree, with the:
#ifndef V4L2_PIX_FMT_SPCA501
#define V4L2_PIX_FMT_SPCA501 v4l2_fourcc('S','5','0','1') /* YUYV per line */
#endif

Approach this works fine, if I were to carry an include tree copy, that would
now need to become a patched include tree copy, and with the next sync I then
need to ensure that any needed patches are either already in the sync source,
or applied again.

Regards,

Hans