AXI fixed burst to a slave with narrow data width

Hi,

I have an AXI master with data width 64, and an AHB slave of data width 32. What would happen when there is a 64bit FIXED burst READ (i.e., asize=3)to an address 0X100 of the slave? 

Would the the data be read from 0x100 only, with data[63:32] always 0? Or would the data be read from 0x100 and 0x104? 

Thanks