Re: [Xen-devel] [RFC PATCH v2 3/3] tools, libxl: handle the iomem parameter with the memory_mapping hcall

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 13.03.14 at 16:27, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> On Mon, 2014-03-10 at 09:25 +0100, Arianna Avanzini wrote:
>> Currently, the configuration-parsing code concerning the handling of the
>> iomem parameter only invokes the XEN_DOMCTL_iomem_permission hypercall.
>> This commit lets the XEN_DOMCTL_memory_mapping hypercall be invoked
>> after XEN_DOMCTL_iomem_permission when the iomem parameter is parsed
>> from a domU configuration file, so that the address range can be mapped
>> to the address space of the domU.
>> NOTE: the added code is still common to both x86 and ARM; it also
>>       implements a simple 1:1 mapping that could clash with the domU's
>>       existing memory layout if the range is already in use in the
>>       guest's address space.
> 
> In that case you need to CC the x86 maintainers (Jan, Keir, Tim) here.
> It doesn't seem to me that this is going to be the correct thing to do
> for either x86 PV or x86 HVM guests.
> 
> My gut feeling is that this should be ifdef'd or otherwise made
> conditional.

At the very least - it really looks more like a temporary hack than
a long term solution to me. Why would we ever want, for other
than experimental purposes, a 1:1 address relationship baked
into anything?

Jan


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