Re: Design doc of adding ACPI support for arm64 on Xen - version 2

[Shannon Zhao <zhaoshenglong@huawei.com>]

On 2015/8/17 18:36, Roger Pau Monné wrote:
> El 11/08/15 a les 16.19, Ian Campbell ha escrit:
>> On Fri, 2015-08-07 at 10:11 +0800, Shannon Zhao wrote:
>>> This document is going to explain the design details of Xen booting with
>>> ACPI on ARM. Maybe parts of it may not be appropriate. Any comments are
>>> welcome.
>>
>> Some small subsets of this seem like they might overlap with what will be
>> required for PVH on x86 (a new x86 guest mode not dissimilar to the sole
>> ARM guest mode). If so then it would be preferable IMHO if PVH x86 could
>> use the same interfaces.
>>
>> I've trimmed the quotes to just those bits and CCd some of the PVH people
>> (Boris and Roger[0]) in case they have any thoughts.
>>
>> Actually, having done the trimming there is only one such bit:
>>
>> [...]
>>> 4. Map MMIO regions
>>> -------------------
>>> Register a bus_notifier for platform and amba bus in Linux. Add a new
>>> XENMAPSPACE "XENMAPSPACE_dev_mmio". Within the register, check if the
>>> device is newly added, then call hypercall XENMEM_add_to_physmap to map
>>> the mmio regions.
>>
>> Ian.
>>
>> [0] Roger is away for a week or so, but I'm expect feedback to be of the
>> "we could use one extra field" type rather than "this needs to be done some
>> totally different way for x86/PVH" (in which case we wouldn't want to share
>> the interface anyway I suppose) so need to block on awaiting that feedback.
> 
> This looks right to me. AFAICT this new memory space
> (XENMAPSPACE_dev_mmio) will only be available to the hardware domain on
> x86. I expect that for DomUs the toolstack will already map the
> appropriate MMIO regions when creating the domain if there are
> pass-through devices assigned, not sure if that's also the plan on ARM.
> IMHO this document should also list the usage of the hypercall parameters:
> 
> - space: XENMAPSPACE_dev_mmio.
> - idxs: native physical addresses.
> - gpfns: guest physical addresses where the mapping should appear.
> 
> This is quite obvious but I think it's worth spelling it out.
> 
Will add. Thanks :)

-- 
Shannon


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