The short answer is no, x64 and ARM CPUs are not natively compatible with each other due to fundamental differences in their architectures. However, with the right software and hardware solutions, it is possible to get x64 and ARM systems to interoperate to some degree.
Key Differences Between x64 and ARM
x64, also known as x86-64 or AMD64, refers to the 64-bit extension of the x86 instruction set architecture developed by AMD. x64 is used in modern 64-bit versions of Windows, Linux, and macOS running on PCs and servers with 64-bit Intel and AMD processors.
In contrast, ARM is a reduced instruction set (RISC) architecture developed by ARM Holdings. Unlike x64, ARM is a licensable architecture, meaning ARM Holdings licenses the ARM instruction sets and architectures to other companies to design their own ARM-based CPUs.
Here are some key differences between x64 and ARM:
- Instruction set – x64 uses complex variable length CISC instructions, ARM uses simpler fixed-length RISC instructions.
- Registers – x64 has 8-16 general purpose registers, ARM has 13-32 registers.
- Addressing modes – x64 has more complex addressing modes, ARM addressing is simpler.
- Architecture – x64 uses little endian data ordering, ARM supports both little endian and big endian.
- Cost and power – ARM CPUs generally use less power and cost less than x64.
- Applications – x64 dominates PCs and servers, ARM dominates mobile and embedded devices.
These underlying differences in the architecture lead to incompatibilities at the machine code level. Code compiled for x64 will not run on ARM, and vice versa.
Similarities Between x64 and ARM
Despite the key differences, x64 and ARM CPUs share some common traits:
- Both use 64-bit registers and datapaths.
- Support common data types like integers, floats, pointers.
- Have conceptually similar hardware resources like general purpose registers, control registers, caches, MMUs etc.
- Capable of running complex modern operating systems like Windows, Linux, macOS.
- Support important security features like DEP, ASLR, NX bit.
These similarities mean that while the machine code is incompatible, higher level languages and APIs can be designed to work on both architectures with the proper abstraction layers.
Achieving Interoperability Between x64 and ARM
There are a few ways interoperability can be achieved between x64 and ARM platforms:
1. Instruction Emulation/Binary Translation
Using emulators or dynamic binary translation, x64 code can be converted to ARM instructions at runtime, allowing x64 programs to run transparently on ARM. Performance overhead can be significant.
Apple uses an emulation layer called Rosetta to run x64 Mac apps on ARM Macs. QEMU can emulate x64 on ARM Linux. Windows on ARM uses emulation for Win32 apps.
2. Cross-Compilation
Applications can be cross-compiled into native binaries for both x64 and ARM. This avoids emulation overhead but requires porting effort.
Mozilla Firefox, VS Code, Node.js distribute official native ARM64 builds alongside x64.
3. Hardware Abstraction Layers
Higher level languages like Java, .NET, Python, Node.js use interpretation or JIT compilation along with HALs to run managed code on any architecture. This provides excellent portability.
.NET Core, Node.js, Python support both x64 and ARM64, enabling full app portability.
4. Hypervisors
Type 1 hypervisors like VMware ESXi, Hyper-V, Xen allow mixing x64 and ARM virtual machines on the same physical server. Guest VMs only see emulated hardware provided by the hypervisor.
AWS Graviton chips power ARM instances that can interoperate seamlessly with x64 instances in the cloud.
ARM-Based Servers for Data Centers
The emergence of 64-bit ARM server CPUs like Amazon’s Graviton is driving increased adoption of ARM in cloud data centers. With the flexibility provided by hypervisors, containers, Kubernetes, microservices, more workloads are becoming portable across architectures.
While ARM servers have advantages in perf/watt, large legacy codebases still favor x64. But for newer cloud-native workloads, ARM’s advantages for density, cost and power efficiency make it appealing for large scale deployments.
So for new apps, targeting both x64 and ARM64 allows taking advantage of both architectures in a complementary manner based on their strengths.
ARM Laptop CPUs for Windows and macOS
On the client side, the launch of Windows laptops powered by Qualcomm Snapdragon ARM processors, and Apple Silicon ARM chips for Macs, brings ARM into the consumer mainstream.
Using extensive emulation layers, the experience across most desktop apps is seamless. But some software still requires native ARM versions for optimal compatibility and performance.
The flexibility to choose ARM laptops for their power efficiency or x64 laptops for maximum compatibility provides consumers more hardware options.
Conclusion
While x64 and ARM CPUs are fundamentally incompatible at the machine code level, modern software and hardware techniques allow achieving interoperability across the architectures. As ARM continues making inroads into client and server markets, this hybrid x64 + ARM ecosystem will likely expand greatly.
Developers can build portable apps using higher level languages and frameworks. IT departments can mix ARM and x64 seamlessly using hypervisors and containers. End users can enjoy both ARM and x64 devices with a unified experience across their apps and workloads.
So rather than compete, x64 and ARM appear positioned to complement each other with their respective strengths in the evolving compute landscape.
