[avr-gcc-list] Re: [avr-chat] task/thread stack usage

[Larry Barello]

My rtos, AvrX, does the same thing with a separate stack for
interrupts.  Switching stacks slows down processing a tad, but saves a
lot of SRAM.  It is not necessary to patch the kernel: I used the
"naked" attribute which had the problem of not setting up a local
frame properly (usually not a problem).  IIRC, the "noreturn"
attribute works now with only two bytes of wasted stack storing the
previous frame pointer, or something like that.

Cheers!

----- Original Message -----
From: "Tvrtko A. Ursulin" <address@hidden>

So in case if interrupts are not nested, each task must accomodate
"largest"
interrupt stack? In my own micro-kernel I have optimized that case in
a way
that interrupts have their own stack. Therefore task stack size is not
related to interrupts. In this way I save (n-1)*max_irq_stack bytes of
RAM.
Where n is total number of tasks.

Drawback is that you need to patch your gcc with my __attribute__
((irq))
patch to be able to write proper interrupt handlers.