Re: [Xen-users] Issues Booting DomU on TI DRA72 Chip

[Brandon Perez <a0225893@xxxxxx>]

On 07/13/2015 04:29 AM, Ian Campbell wrote:
> On Fri, 2015-07-10 at 11:21 -0400, Brandon Perez wrote:
>
> Is there a 1:1 mapping between (active) interrupts handled by this
> cascaded controller a SPIs? i.e. if there were 32 interrupts but only 16
> SPIs would you only be able to use 16 of the devices?
>
> Or does it support multiple interrupt sources triggering a single SPI?
    For the chip I'm working with, it only supports a 1:1 mapping. It 
doesn't allow for multiple interrupts to share an SPI line.
> Right, this is a tricky one. Other than various solutions involving
> trusting the firmware to get it right and requiring dom0 to not muck
> around with it the only other solution I can think of would be a bit of
> code in Xen which traps dom0's attempted changes and validates them,
> preventing dom0 from mucking with the ones Xen cares about.
>
> Given how simple these sorts of interrupt remappers often are that might
> not even be that much code.
>
> Ian.
    I think that wouldn't be too difficult to do, but for now, I'm 
going to stick with using the device tree to inform Xen and the Kernel.
Brandon

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