Wait, where are you going to merge the multiproto drivers to? Am I
reading it correct that you'll get them in the dvb-4vl tree or.. What
am I missing here? :)
This has been one hell of a day!
Met vriendelijke groeten,
Jelle De Loecker
Kipdola Studios - Tomberg
Manu Abraham schreef:
Oliver Endriss wrote:
Hans Werner wrote:
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.
Notes:
* same API structure, I just added some new enums and variables, nothing
removed
* no changes required to any existing drivers (v4l-dvb still compiles)
* no changes required to existing applications (just need to be
recompiled)
* 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.
Michael,
thank you for your comment.
I understand, but I think binary compatibility *should* be broken in this case. It makes
everything else simpler.
No way. Breaking binary compatibility is a no-go.
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.
The only way to support DVB-S2 in a reasonable way is adding a new API.
Multiproto does this.
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
halt.
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.
The linux distribution maintainers would kill you.
Applications must continue to run after a kernel update.
I would be interested to hear your opinion on how we can move forward rapidly.
Multiproto should be merged asap.
True. Sorry about the long delay, just got back after quite a long
journey. Will do so these following days.
Regards,
Manu
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