On 12/11/2017 02:40 PM, Arnd Bergmann wrote:
On Mon, Dec 11, 2017 at 11:25 AM, Linus Walleij
<linus.walleij@xxxxxxxxxx> wrote:
On Fri, Dec 8, 2017 at 3:11 PM, Ludovic Barre <ludovic.Barre@xxxxxx> wrote:
From: Ludovic Barre <ludovic.barre@xxxxxx>
This patch prepares the STM32 machine for the integration of Cortex-A
based microprocessor (MPU), on top of the existing Cortex-M
microcontroller family (MCU). Since both MCUs and MPUs are sharing
common hardware blocks we can keep using ARCH_STM32 flag for most of
them. If a hardware block is specific to one family we can use either
ARCH_STM32_MCU or ARCH_STM32_MPU flag.
Signed-off-by: Ludovic Barre <ludovic.barre@xxxxxx>
To what degree do we need to treat them as separate families
at all then? I wonder if the MCU/MPU distinction is always that
clear along the Cortex-M/Cortex-A separation, especially if
we ever get to a chip that has both types of cores. What
exactly would we miss if we do away with the ARCH_STM32_MCU
symbol here?
This patch series extends the existing STM32 microcontrollers (MCUs)
family to microprocessors (MPUs). Now, ARCH_STM32 groups STM32 chips
with Cortex-M or Cortex-A cores. But each core has different
infrastructure mpu vs mmu; nvic vs gic; systick vs arch_timer ...
So, ARCH_STM32_MCU/ARCH_STM32_MPU allow to define these specific blocks.
br
Ludo
So yesterdays application processors are todays MCU processors.
I said this on a lecture for control systems a while back and
stated it as a reason I think RTOSes are not really seeing a bright
future compared to Linux.
It happened quicker than I thought though, interesting.
I think there is still lots of room for smaller RTOS in the long run,
but it's likely that the 'MPU + external DRAM' design point will
shift further to Linux, as there isn't really a benefit in squeezing
in anything smaller when the minimum is 32MB or 128MB of
RAM, depending on the interface.
For on-chip eDRAM or SRAM based MPUs, that doesn't hold
true, the memory size is what drives the cost here.
Arnd
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