Re: [Xen-devel] [ARM] Handling CMA pool device nodes in Dom0

[Julien Grall <julien.grall@xxxxxxx>]

(CC Stefano)

On 25/11/16 12:19, Iurii Mykhalskyi wrote:
> Hello!
Hi Iurii,

> I'm working under Renesas Gen3 H3 board with 4GB RAM (Salvator-X)
> support in Xen mainline.
>
> Salvator-X has several  CMA pool nodes, for example:
>
> 1:
> adsp_reserved: linux,adsp {
> compatible = "shared-dma-pool";
> reusable;
> reg = <0x00000000 0x57000000 0x0 0x01000000>;
> };
>
> 2:
> linux,cma {
> compatible = "shared-dma-pool";
> reusable;
> reg = <0x00000000 0x58000000 0x0 0x18000000>;
> linux,cma-default;
> };
>
> During Dom0 allocation, we can't guarantee, that allocated memory will
> contain mentioned regions.
> In second сase, we can actually hardcode mapped region by using separate
> DTS for Dom0 with changed memory regions.
> But for first one, this in not an option - this pool is used for audio
> DSP and its firmware relies on this addresses.
>
> What is the correct way to solve this situation?
> Does Xen has some mechanism to handle such cases?
From my understanding all the nodes you mentioned are living under the 
node /reserved-memory, right? Currently Xen is not parsing this node.
Before answering about possible implementation in Xen, I would like to 
understand what are the constraints on these reserved memory regions.
I understand that when "reg" property is specified, it is a static 
allocation and we need to be able to map those regions at the same 
address in DOM0.
However, do these regions need to be included in memory node?

Regards,

--
Julien Grall

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