On Thu, Jul 26, 2018 at 9:08 PM Sebastian Andrzej Siewior <sebastian.siew...@linutronix.de> wrote: > > On 2018-07-18 20:19:15 [+0530], Pintu Kumar wrote: > > Hi All, > Hi, > > > I have a question about PREEMPT_RT patch for 3.10 kernel. > > I am trying to port this rt patch: 0224-printk-rt-aware.patch.patch > > (see the patch below), in non-rt kernel. > > I could able to successfully apply this patch after replacing: > > migrate_enable/disable with preempt_enable/disable. > > Things were working fine so far. > > Why? > > > Then, I noticed that "printk" from interrupt context is not appearing > > on console (minicom), if console shell is active. > > However, it appears on the dmesg output. > > > > So, I am wondering, what could be the cause of this patch for this > > behavior in non-rt kernel? > > Is this the expected behavior, even on PREEMPT_RT kernel? > > I *think* it is but there are hardly any prints from atomic context for > anyone to notice. And the next print from non-atomic context should > flush it out. > Yes, we observed the same behavior with CONFIG_PREEMPT_RT_FULL with beagle bone-rt kernel 4.9. And yes, after doing : echo "1234" > /dev/kmsg the content were flushed. So, I guess this is the expected behavior with this patch.
> > Is there a way we can fix this issue on non-rt kernel? > I would guess that a wakeup to klogd would fix it. > Sorry, can you elaborate more about "wakeup to klogd". I wanted to try it and check. > > Please help us with your suggestions. > > > > Thanks, > > Pintu > > Sebastian
