On Fri, 2010-02-26 at 22:03 +0000, Russell King - ARM Linux wrote: > On Sat, Feb 27, 2010 at 08:49:40AM +1100, Benjamin Herrenschmidt wrote: > > It will deadlock if you use normal IRQs. I don't see a good way around > > that other than using a higher-level type of IRQs. I though ARM has > > something like that (FIQs ?). Can you use those guys for IPIs ? [...] > The other problem we'd encounter using FIQs for IPIs is that some IPIs > need to take locks - and in order to make that safe, we'd either need > another class of locks which disable IRQs and FIQs together, or we'd > need to disable FIQs everywhere we disable IRQs - at which point FIQs > become utterly pointless. You could use the FIQ only for the DMA cache maintenance operations and not as a generic IPI mechanism. But the hardware needs to be modified. -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
