USB HID driver fails to recognize input devices

[Julian Stecklina]

Udo Steinberg <udo at ...121...> wrote:

>On Fri, 20 Jul 2012 12:22:37 -0700 Julian Stecklina (JS) wrote:
>JS> Udo, is there an easy way to figure out, if a system supports
>Interrupt
>JS> Remapping short of looking into ACPI tables?
>
>You could infer that from looking at the MSI data provided by the
>hypervisor.
>Or the hypervisor could announce it in the HIP. But like I said,
>userland
>doesn't really need to know.

I meant  it more in the way of figuring out which test box to use. :-) ark.intel.com doesn't list this unfortunately. 

And yes, correct userland code should be completely oblivious to whether IRQ remapping is used.

>JS> > (I'm thinking about adding some code to the hypervisor, causing
>sem_down to
>JS> > fail on an interrupt semaphore unless the interrupt has been
>configured
>JS> > using assign_gsi.)
>JS> 
>JS> +1 from me. That would cause broken code to fail early.
>
>The reason I haven't done it yet, is, that it adds a branch to every
>sem_down
>on an interrupt semaphore, which is overhead you pay every time, just
>to get
>some additional checking at initialization time.

You could enable it only for debug builds, but I don't think it makes any noticeable difference either way.

Julian

-- 
Sent from my phone. Please excuse my brevity.