[Qemu-devel] Single 64bit memory transaction instead of two 32bit memory transaction.

[Adnan Khaleel]

In the file exec.c:

The memory Write/Read functions are declared as an array of 4 entries where the 
index values of 0,1,2 correspond to 8,16 and 32bit write and read functions 
respectively.

CPUWriteMemoryFunc *io_mem_write[IO_MEM_NB_ENTRIES][4];
CPUReadMemoryFunc *io_mem_read[IO_MEM_NB_ENTRIES][4];

Is there any reason why we can't extend this to include 64bit writes and read 
by increasing the array size? This is because 64bit reads are currently handled 
as two separate 32bit reads for eg: sommu_template.h

static inline DATA_TYPE glue(io_read, SUFFIX)(target_phys_addr_t physaddr,
                                              target_ulong addr,
                                              void *retaddr)
{
:
    res = io_mem_read[index][2](io_mem_opaque[index], physaddr);
    res |= (uint64_t)io_mem_read[index][2](io_mem_opaque[index], physaddr + 4) 
<< 32;
:
    return res;
}

I'm sure this is happening in other places as well. Is there a reason for this 
or could we arbitrarily increase this (within limits ofcourse)?

Thanks

AK