I'm working with a small embedded O/S on an ARM7TDMI.
A typical IRQ handler must save the state of a previous task, perform
some processing, possibly invoke the scheduler, and then restore a new
task. I'd like to do as much of this as possible from C, but
automatically generated prologue/epilogue chunks interfere with my
IRQ_TASK_SAVE/RESTORE macros (which are inline assembly). So I've been
doing this:
static void emac_irq(void) __attribute__ ((naked));
static void emac_irq(void)
{
IRQ_TASK_SAVE;
emac_irq_real();
IRQ_TASK_RESTORE;
}
Calling out to the actual ISR as a separate function call seems to
isolate stack variable allocations to the section between the
IRQ_TASK_SAVE/RESTORE.
This works pretty well, however, if I optimize at -O4, emac_irq_real is
inlined, and the IRQ handler no longer runs correctly. (I've verified:
the code works with -O4 -fno-inline, but doesn't work with just -O4).
I can attach a "noinline" attribute to emac_irq_real, which again causes
things to work, but the whole thing is starting to feel clumsy.
Does anyone have an idea of how I can do this in a more elegant way,
that doesn't require setting a bunch of attributes?
-Ed
