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 _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
