Re: [PATCH/RFC] PCI prepare/activate instead of enable to avoid IRQ storm and rogue DMA access

Russell King
2007-03-14T21:56:06Z

On Thu, Mar 15, 2007 at 12:23:02AM +0900, Tejun Heo wrote:
> The problem is that a PCI device can be in any arbitrary when it gets
> enabled and the device has to be enabled for its driver to
> initialize/reset it. The most common case this causes headache is as
> follows.
>
> Let's assume there's a device which shares its INTX IRQ line with
> another device and the other one is already initialized.

pci_enable_device() doesn't deal with this; in most PCI setups I've
seen, there is no control at PCI level over whether a device generates
an interrupt on the bus. Certainly the memory and io command enables
have no effect on the ability of the device to cause an interrupt.

In most cases, only the driver of the device knows how to disable
interrupts on any particular device.

--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/