Hi list, I'm part of a project that recently added PREEMPT_RT support (as well as Xenomai) to LinuxCNC/EMC2. The next sub-project is a 'universal binary'. The LCNC real-time module will run some checks to determine what RT systems, if any, are available on the running kernel, and then load the appropriate RT support module. We wish to distinguish between PREEMPT_RT and non-RT kernels because LCNC must confirm that the kernel really does have realtime capabilities, if that's what the user expects, and print big warning messages if not. LCNC drives machines that weigh many tons and spins spindles at 24k RPM, so this is important! The RT PREEMPT HOWTO discusses checking the kernel here: https://rt.wiki.kernel.org/index.php/RT_PREEMPT_HOWTO#Checking_the_Kernel One method is to use string matching against the kernel version, which I'm a bit suspicious of. An improvement, figure 7 suggests using string matching against the process list in search of kernel thread names matching '[softirq-foo]'. Figure 8 show how to check /proc/interrupts on older kernels, but 9 states this doesn't work for newer kernels, so this isn't an option. We haven't found /proc/config.gz in any vendor-provided PREEMPT_RT kernels, so that is not an option either. So, is string matching against the process list the best detection method, or is there something I've missed? John -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
