[linux-dvb] [PATCH] Future of DVB-S2
Jelle De Loecker
skerit at kipdola.com
Fri Aug 29 18:50:23 CEST 2008
I wasn't really focusing the haupage drivers, more the multiproto
drivers manu created.
I have a TT S2-3200.
You're talking about upcoming change in the HVR4000 world? Do you know
anything about our little technotrend cards?
/Met vriendelijke groeten,/
*Jelle De Loecker*
Kipdola Studios - Tomberg
Hans Werner schreef:
>>> Now, to show how simple I think all this could be, here is a PATCH
>> implementing what
>>> I think is the *minimal* API required to support DVB-S2.
>>> * same API structure, I just added some new enums and variables, nothing
>>> * no changes required to any existing drivers (v4l-dvb still compiles)
>>> * no changes required to existing applications (just need to be
>>> * no drivers, but I think the HVR4000 MFE patch could be easily adapted
>>> I added the fe_caps2 enum because we're running out of bits in the
>> capabilities bitfield.
>>> More elegant would be to have separate bitfields for FEC capabilities
>> and modulation
>>> capabilities but that would require (easy) changes to (a lot of) drivers
>> and applications.
>>> Why should we not merge something simple like this immediately? This
>> could have been done
>>> years ago. If it takes several rounds of API upgrades to reach all the
>> feature people want then
>>> so be it, but a long journey begins with one step.
>> This will break binary compatibility with existing apps. You're right
>> -- those apps will work with a recompile, but I believe that as a
>> whole, the linux-dvb kernel and userspace developers alike are looking
>> to avoid breaking binary compatibility.
> thank you for your comment.
> I understand, but I think binary compatibility *should* be broken in this case. It makes
> everything else simpler.
> I know that not breaking binary compatibility *can* be done (as in the HVR4000 SFE and
> MFE patches) but at what cost? The resulting code is very odd. Look at multiproto which
> bizarrely implements both the 3.2 and the 3.3 API and a compatibility layer as well, at huge cost
> in terms of development time and complexity of understanding. The wrappers used in the MFE
> patches are a neat and simple trick, but not something you would release in the kernel.
> If you take the position the binary interface cannot *ever* change then you are severely
> restricting the changes that can be made and you doom yourself to an API that is no longer
> suited to the job. And the complexity kills. As we have seen, it makes the whole process grind to a
> Recompilation is not a big deal. All distros recompile every application for each release (in fact much more frequently -- updates too), so most users will never even notice. It is much better to make the right, elegant changes to the API and require a recompilation. It's better for the application developers because they get a sane evolution of the API and can more easily add new features. Anyone who
> really cannot recompile existing userspace binaries will also have plenty of other restrictions and
> should not be trying to drop a new kernel into a fixed userspace.
> I would be interested to hear your opinion on how we can move forward rapidly.
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