Re: [Xen-devel] XEN on R-CAR H3

[Oleksandr <olekstysh@xxxxxxxxx>]

> Hi Oleksandr,
Hi, Julien


> > There is a question which worries me and likely other people as well. 
> > Which is "reserved memory area support in Xen". Some SoCs except 
> > application processors have some IPs (co-processors, dsps, codecs, 
> > whatever) which rely on a specific predefined memory regions, or even 
> > can work with these memory regions only...
> This discussion came-up time to time on the ML. I would love to see 
> patches we can discuss :)
> > Without this feature being supported, we won't be able to use IPs, 
> > whose firmware requires a predefined memory region to talk to an 
> > application processor, I am afraid.
> > One option comes to mind... I presume, the use of "iomem" property in 
> > domain config could allow us to assign 1:1 mapped region to that 
> > guest domain. Would it be a correct option?
> > What needs to be implementing it Xen, for example, to have a 
> > possibility to assign a particular reserved memory region(s) to a 
> > particular guest domain?
> Well, for a first you need to deal with Xen and Dom0. For instance, 
> Xen allocator should not be able to use that memory for a normal RAM 
> page.
I understand.


> There was some discussions on the ML a long time ago with Andrii (see 
> [1]). Maybe he has some patches ready for it.
> Cheers,
>
> [1] 
> https://lists.xenproject.org/archives/html/xen-devel/2017-07/msg02674.html

Thank you for the pointer. I will read it.


--
Regards,

Oleksandr Tyshchenko


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