Re: [Xen-devel] Xen: Support for mapping OperationRegion in ACPI ASL

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 20.12.16 at 00:01, <sstabellini@xxxxxxxxxx> wrote:
> This is actually not an ARM specific question, so changing the subject
> and CC'ing more people.
> 
> On Wed, 14 Dec 2016, Konrad Rzeszutek Wilk wrote:
>> On Tue, Dec 13, 2016 at 07:14:27PM -0600, Jiandi An wrote:
>> > Xen currently does not handle mapping of MMIO regions specified under 
> OperationRegion in ACPI ASL.  OperationRegion is well defined in ACPI 
> specification.  I'm seeking for architectural direction on adding support for 
> mapping OperationRegion.
>> > 
>> > Some context here.  Mapping of resources specificed under _CRS in ACPI is 
> handled by dom0 requesting Xen to map as platform devices are added.  
> https://lwn.net/Articles/674666/ provided service xen_map_device_mmio() in 
> dom0 to call Xen to map and it's done so by registering 
> xen_platform_notifier() platform bus driver.  This covers the platform 
> devices.
>> > 
>> > The OperationRegion access in dom0 is in acpica path.  The following is a 
> stack of the code path where OperationRegion is parsed.  

But aren't such regions required to be claimed by resource
declarations elsewhere? I don't think the mapping (into the p2m)
should happen during an access attempt, but much earlier. But
perhaps I'm missing some context ...

Jan


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