Peter Maydell <peter.mayd...@linaro.org> writes:
> On Wed, 5 Jan 2022 at 21:05, Alex Bennée <alex.ben...@linaro.org> wrote:
>> Can't be added as a subregion to the container...
>>
>> qemu-system-arm: ../../softmmu/memory.c:2538:
>> memory_region_add_subregion_common: Assertion `!subregion->container' failed.
>
> This assert means you tried to add the same MemoryRegion
> as a subregion of more than one parent MR.
Right - that is probably something we should make (more?) explicitly
clear in the Memory API docs.
> You can either:
> * pass all the CPUs the same container as their "memory" link,
> if they all see the same view of the world
This should be the case - I don't think the different cores have any
particular different view of the world. The use of the two 4kb banks I
think is purely convention.
However trying for a single container shared between both cores fails
because armv7m_realize adds it's board_memory to another container:
memory_region_add_subregion_overlap(&s->container, 0, s->board_memory, -1);
So I guess I just have to repeat the creation of the aliases for each
core. This seems needlessly messy...
> * if they have different views of the world, you need to
> create a container for each CPU to be the "memory" link,
> and to populate that container you need to create N-1 alias MRs
> of the board_memory MR (CPU 0's container can use the original
> board_memory MR; CPU 1, ... use the aliases).
>
> Example of option 1: virt board
> Example of option 2: hw/arm/armsse.c (look at what it does with
> the s->cpu_container[] and s->container_alias[] arrays)
>
> -- PMM
--
Alex Bennée
