On 15 June 2015 at 15:44, Alex Züpke <alexander.zue...@hs-rm.de> wrote: > Am 12.06.2015 um 20:03 schrieb Peter Maydell: >> Probably the best approach would be to have something in >> arm_cpu_set_irq() which says "if we are CPU X and we've >> just caused an interrupt to be set for CPU Y, then we >> should ourselves yield back to the main loop". >> >> Something like this, maybe, though I have done no more testing >> than checking it doesn't actively break kernel booting :-) > > > Thanks! One more check for "level" is needed to get it work:
What happens without that? It's reasonable to have it, but extra cpu_exit()s shouldn't cause a problem beyond being a bit inefficient... It would be interesting to know if this helps Linux as well as your custom OS. (I don't know whether a "CPU #0 polls" approach is bad on hardware too; the other option would be to have CPU #1 IPI back in the other direction if 0 needed to wait for a response.) -- PMM
