I realize the BBB is a single-core SoC. My point is enabling PREEMPT code in the kernel *REQUIRES* all kernel code to be SMP safe (even when running on a single core!), which is why this option causes stability issues.
As for the multi-core TI chips with similar drivers, it is not uncommon for drivers to (mostly) work in a multi-core system without *REALLY* being SMP safe. See the history of integrating the PREEMPT patch set to the mainline kernel for a laundry list of obscure, hard-to-trace kernel bugs that were uncovered in the process, even though Linux had been running on multi-core x86 systems for quite some time. On 9/18/2014 12:34 PM, neo star wrote: > Hi Charles the BBB is a single core Soc > > On Thu, Sep 18, 2014 at 10:47 PM, Charles Steinkuehler > <char...@steinkuehler.net> wrote: >> On 9/18/2014 11:40 AM, Robert Nelson wrote: >>> >>> sudo apt-get update >>> sudo apt-get install linux-image-3.14.19-ti-r22 >>> >>> has: CONFIG_PREEMPT_VOLUNTARY >>> >>> In the past, preempt broke a lot of things. So i'm always hesitant to >>> enable it by default across the board. >> >> PREEMPT has a tendency to tickle obscure bugs in non-SMP safe kernel >> code. Many nasty bugs were uncovered as the PREEMPT code got merged >> into the kernel. Now the core kernel is very SMP safe, but there are >> still a lot of drivers (ie: "vendor-supplied code for single-core SoCs") >> that are not SMP clean. >> >> As multi-core ARM systems become more common, the situation should >> improve (as it did with the x86 over time). >> >> -- >> Charles Steinkuehler >> char...@steinkuehler.net >> >> -- >> For more options, visit http://beagleboard.org/discuss >> --- >> You received this message because you are subscribed to a topic in the >> Google Groups "BeagleBoard" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/beagleboard/4eDQvQOkUkc/unsubscribe. >> To unsubscribe from this group and all its topics, send an email to >> beagleboard+unsubscr...@googlegroups.com. >> For more options, visit https://groups.google.com/d/optout. > -- Charles Steinkuehler char...@steinkuehler.net -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
