Re: [Qemu-devel] External RAM

[Brian Roantree]

Thanks for the reply however as my boss was sat watching me I wound up taking 
another direction.

Because I knew the address of the block of RAM and the name I was calling it 
with I was able to create a block. Instead of using malloc to allocate the 
memory for it, I set the address for the RAM to the address of the external 
block I'd created meaning that all the standard RAM functions should work :)

When I have some time I'll have to try creating and using ROMD 
        
>-----Original Message-----
>From: Blue Swirl [mailto:address@hidden 
>Sent: 01 September 2012 10:26
>To: Brian Roantree
>Cc: address@hidden
>Subject: Re: [Qemu-devel] External RAM

>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.