Re: [Qemu-devel] External RAM

[Blue Swirl]

On Wed, Aug 29, 2012 at 1:38 PM, Brian Roantree
<address@hidden> wrote:
> Hi, I’m not sure which list this belongs in and was unable to find anything
> like it so here goes,
>
>
>
> I am using QEMU 0.15.90 to emulate a processor and have currently got it
> running in a loosely timed simulation with a systemC kernel as well, I have
> also  created and attached a block of RAM as well as another device and am
> running into a problem. It is registered as IO memory and replaced the
> generic internal ram that was allocated using qemu_ram_alloc, the problem
> I’m having is that my bootloader is now trying to write to RAM address
> 4293918720 (0xFFF00000) which doesn’t exist. My question is can I somehow
> use qemu_ram_alloc to allocate the RAM but still use the different IO
> functions to read and write from this block of memory?
>
>
>
> I have tried creating a device for the ram and after initialising it using
>
>
>
> Addr = qemu_ram_alloc(s->sc_shared_ram,”name.ram”, ram_size);
>
> cpu_register_physical_memory(addr_base, ram_size, Addr);
>
> where s is processor device_state and sc_shared_ram is a device_state with
> the modified read and write functions
>
>
>
> however when the Ram is used the read and write functions are never
> employed.
>
>
>
> Any help you could provide would be much appreciated, also apologies if I’m
> not that clear with my wording I haven’t been doing QEMU development that
> long so am not also sure how to express what I want.

Either the memory is registered as MMIO (but then it's not possible to
execute code from it), or it's registered as RAM (but then it's not
possible to register MMIO handlers). In between those, there's ROMD,
which is read as RAM but written as MMIO device.