From: Paul Thompson
Date: Wed Dec 19 2012 - 02:22:08 EST


Perhaps Im being an idiot, but it looks to me like the
menu-item for SPARSE_IRQ (under General setup -> IRQ subsystem)
depends solely on MAY_HAVE_SPARSE_IRQ, but I only see *one* user
for that in the kernel now, the SuperH arch (arch/sh/Kconfig). It
looks like everyone else explicitly sets SPARSE_IRQ. However the
menu-items description implies it is a more generic option...
It seems like this menu item used to appear, in a forced
on state, then this condition made it disapear, leaving a blank
IRQ subsystem menu for me. I was trying to work around that, but
now, I am not sure exactly what is supposed to be going on here...


(from kernel/irq/Kconfig)
bool "Support sparse irq numbering" if MAY_HAVE_SPARSE_IRQ

Sparse irq numbering is useful for distro kernels that want
to define a high CONFIG_NR_CPUS value but still want to have
low kernel memory footprint on smaller machines.

( Sparse irqs can also be beneficial on NUMA boxes, as they spread
out the interrupt descriptors in a more NUMA-friendly way. )

If you don't know what to do here, say N.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at