Re: [Qemu-devel] [PATCH] dimm: Correct type of MemoryHotplugState->base

[Paolo Bonzini <pbonzini@redhat.com>]

On 22/01/2016 11:02, Igor Mammedov wrote:
> On Thu, 21 Jan 2016 12:37:51 +1100
> David Gibson <david@gibson.dropbear.id.au> wrote:
> 
>> The 'base' field of MemoryHotplugState is ram_addr_t, which indicates that
>> it exists in the abstract address space of RAM regions.
>>
>> However, the actual usage of this field indicates that it is a concrete
>> physical address (it's passed as an offset to memory_region_add_subgregion
>> for example).
>>
>> So, correct its type to 'hwaddr'.
>>
>> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
>> ---
>>  include/hw/mem/pc-dimm.h | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/include/hw/mem/pc-dimm.h b/include/hw/mem/pc-dimm.h
>> index d83bf30..218dfb0 100644
>> --- a/include/hw/mem/pc-dimm.h
>> +++ b/include/hw/mem/pc-dimm.h
>> @@ -77,7 +77,7 @@ typedef struct PCDIMMDeviceClass {
>>   * @mr: hotplug memory address space container
>>   */
>>  typedef struct MemoryHotplugState {
>> -    ram_addr_t base;
>> +    hwaddr base;
>>      MemoryRegion mr;
>>  } MemoryHotplugState;
>>  
> 
> I agree with this fix but that's not the only place where
> ram_addr_t needs to be replaced with hwaddr.
> For example type of MachineState.[max]ram_size fields needs
> to be changed as well. Because QEMU builds without CONFIG_XEN_BACKEND
> on 32-bit hosts are broken since ram_addr_t is 32-bits there
> while some targets assume and use it as 64-bit one.

But on a 32-bit system without CONFIG_XEN_BACKEND you cannot allocate
more than 4G anyway, so the choice of ram_addr_t is understandable in
that case.

On the other hand, on a 32-bit system without CONFIG_XEN_BACKEND you
definitely can place 128M of hot plugged memory between say 4096MB and
4224MB.

Paolo