aligned_malloc
void* aligned_malloc(size_t required_bytes, size_t alignment);
fDescs = (VirtioDesc*)aligned_malloc(sizeof(VirtioDesc) * fQueueLen, 4096);
fAvail = (VirtioAvail*)aligned_malloc(sizeof(VirtioAvail)
fUsed = (VirtioUsed*)aligned_malloc(sizeof(VirtioUsed)