On Mon, Sep 29, 2014 at 01:46:50PM -0700, javqui wrote: > Hi, > I'm working on a couple of projects requiring the classic Micro controller > features (low power, deterministic real time processing) and the classic > UX, flexibility and functionality of Linux /android. > > Most SoCs today provide many high level external hardware interfaces (like > Camera, USB, HDMI, etc) but some projects require additional drivers and > interfaces to handle different external hardware. Usually we solve the > interconnectivity with extra MCUs, FPGAs or other specialized chip > interfaces available. > > Sometimes, we design product boards with two solutions: a Cortex A SoC like > Allwinner/rockchip/Omap series and a small MCU Cortex M like the STM32 > series, but with a powerful A80, it could change forever. > > I will receive my first Optimus board soon, and I want to customize the > kernel to create a classic Linux running on the powerful 4x A15+ GPU and > Nucleus (or Free RTOS) on one or two of the A7 of the Allwinner A80 Soc. (I > made similar kernel works with MTK SoCs in the past, but never try to run > two operating systems in the same chip at the same time) > > Both projects require continuous operation and deterministic real time > response on the low power processor(s) (RTOS on A7). > User interaction (Linux on the A15 + GPU side ) is only eventual, so termal > issues by running almost all processors at the same time occasionally, > should not be a problem. > > If anyone anticipate a significant barrier to build a kernel of this type, > please share it here, I will really appreciate. I will share the results > and evaluation test here
What might be easier for you, and probably less intrusive from the kernel point of view, would be to use the co-processor that some Allwinner SoCs have. I know the A31 has one, and I'm pretty sure the A80 too. That would leave Linux in charge of the "real" CPUs, while offloading your RT tasks to a smaller processor, without having to deal with all the segmentation in the bootloader. And if you're used to using Cortex-M, you shouldn't need all that horsepower anyway. Maxime -- Maxime Ripard, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com
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