Re: PMU and timer interrupts

[Stephane Eranian <eranian@hpl.hp.com>]

Jes,

On Fri, Feb 10, 2006 at 06:26:34PM -0500, Jes Sorensen wrote:
> >>>>> "Ken" = Chen, Kenneth W <kenneth.w.chen@intel.com> writes:
> 
> Ken> By hardware, upon an interrupt, both psr.i and psr.ic bit are off
> Ken> when the control goes into the ivt:interrupt().  In there,
> Ken> pt_regs is saved and only psr.ic bit is turned on.  It eventually
> Ken> calls down to handle_IRQ_event(). Since SA_INTERRUPT flag is on
> Ken> for timer interrupt, kernel doesn't enable irq when invoking the
> Ken> handler.
> 
> Ken> In fact, most of the interrupts having SA_INTERRUPT flag set.  So
> Ken> the blind spots you worried about for PMU is a lot wider.  For
> Ken> example, on my system, serial, e1000, mpt fusion, qla2300
> Ken> interrupts all have that flag set. Looks like kernel executes
> Ken> these handlers with irq disabled all the way through.
> 
> Ken,
> 
> I wonder if that isn't mostly bugs on the driver authors side?
> SA_INTERRUPT was really introduced to handle UART interrupts, whereas
> I think  all the other drivers you mention ought to be able to handle
> it correctly.
> 

Who would know for sure wether interrupt masking is really needed 
on those drivers?

-- 
-Stephane