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I wish to install Xenomai which works on Linux providing a kind of hard real time environment. x86/64 architectures are supposed to contain the "System Management Mode" which prevents them from being used for hard real time systems. By "System Management Mode" I mean this: http://en.wikipedia.org/wiki/System_Management_Mode Do embedded boards like ARM also have this "System Management Mode"? |
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System Management Mode is not the only thing that makes x86 bad at hard real time. The unpredictability of the execution speed due to caches, pipelines and so on makes x86, and any other high-end processor, bad at real time. All these features that make a processor fast on average also make the worst case difficult to manage. The current generation of ARM chips is divided in three series: Cortex A for high-end microprocessors (the closest thing to x86), Cortex-R for real-time applications, and Cortex-M in a microcontroller profile. The Cortex-R does not have an MMU (some have an MPU) but may have a cache. It is used in many real-time applications (ARM tries to compete with DSPs, fairly successfully). The ARM architecture itself does not define anything like SMM. It's possible that chip manufacturers add something like it, you'd have to look at the manufacturer's documentation. |
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See the section on Exceptions and Interrupts here: http://wiki.osdev.org/ARM_Overview#Exceptions.2C_IRQs_and_Software_Interrupts_on_ARMv4_and_up Basically, the answer is no. ARM CPUs do not have a "System Management Mode" or SMM. On ARM CPUs, the OS kernel handles the interrupts. |
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