Jan Kiszka wrote: > Gilles Chanteperdrix wrote: >> Jan Kiszka wrote: >>> Why? It delivers us the core mechanism we need for the rest as well - >>> and it does not require fancy I-pipe hooks. >> Because relying on the vdso/vsyscall only works on x86. Whereas >> implementing clock slew down/acceleration at nucleus level and simply >> sharing data between kernel and user through the the global sem heap, >> works for all architectures. > > There are three kind of archs: > - those that already support vgettimeofday & friends (x86, powerpc, > maybe more) > - those that do not yet though they could (I strongly suspect arm falls > into this category as well) > - those that never will (due to lacking user-readable time sources) > > We need temporary/permanent i-pipe workarounds for the last two, but I > see no point in complicating the first category. This design aims at a > longer term.
Well, I may be wrong, but I prefer generic code to arch-specific code. Nucleus code to handle clock slow down/acceleration would be generic; I-pipe code to signal NTP syscalls would be generic (and yes, even if I-pipe patches are generated for all architectures, whether the code is generic or specific makes a big difference); User-space code to implement clock_gettime(CLOCK_REALTIME) using data shared through the global sem heap would be generic. So, I think this design is future proof and easy to maintain. And I do not see how it complicates x86 situation, since it is only made of generic code. Looks like we found a troll to occupy this afternoon :-). -- Gilles _______________________________________________ Xenomai-core mailing list Xenomaifirstname.lastname@example.org https://mail.gna.org/listinfo/xenomai-core