Re: [Xen-devel] Design doc of adding ACPI support for arm64 on Xen - version 4

[Shannon Zhao <zhaoshenglong@xxxxxxxxxx>]

Hi Roger,

On 2015/8/19 23:02, Roger Pau Monné wrote:
> El 19/08/15 a les 14.13, Shannon Zhao ha escrit:
>> 4. Map MMIO regions
>> -------------------
>> Register a bus_notifier for platform and amba bus in Linux. Add a new
> 
> Can we make this OS agnostic? Could you explain what you mean with the
> above sentence without using Linux kernel internals?
> 
Ok, will change it.

>> XENMAPSPACE "XENMAPSPACE_dev_mmio". The usage of this hypercall
>> parameters:
>> - domid: DOMID_SELF.
>> - space: XENMAPSPACE_dev_mmio.
>> - gpfns: guest physical addresses where the mapping should appear.
> 
> This is not complete, you have forgotten to add the idxs field, 

Sorry, I didn't use the idx for the mmio region mapping. What's the idx
useful for here?

> and I
> don't think the domid field needs an explanation TBH.
> 
>>
>> Within the register, check if the device is newly added, then call
>> hypercall XENMEM_add_to_physmap to map the mmio regions.
>>
>> For PCI bus device, it could reuse the existing PCI bus_notifier like
>> X86.
> 
> What is a PCI bus_notifier? I don't see any mention of bus_notifier in
> Xen code.
> 
I thought You konw what I mean here. If not, what should I do! Yeah, as
you said, I will change the description.

But I want to say that the purpose of this document is to explain some
important implementation details for ACPI support on ARM, which have
some divergence before. I don't hope this doc to be official but I do
hope this lets us reach an agreement on the approach before respinning
the patches. If we focus on the words or description or even
word-splitting, it doesn't help to make this move on!

> In general the text above seems more like a description of the Linux
> implementation rather than a Xen design document. Could you explain
> without using Linux internals how/when this new hypercall should be used?
> 
> If you want you can provide examples about how this new interface is
> going to be used in Linux, but the general description should remain OS
> agnostic IMHO.
> 
> Roger.
> 
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> 
> .
> 

-- 
Shannon


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