Quick AnswerNo, those .pyc files you created on your x86_64 PC aren't secure, they're not the best fit, and they'll likely get recreated fresh on the ARM64 board—as long as Python can write to the file system there. The wonky system clock on the board could throw a wrench into that process, though.Digging Deeper1. Are .pyc Files from x86_64 a Security Headache on ARM64?Security worries with .pyc files aren't usually a big deal, since they're not like sneaky native code that could run wild. Let's break it down:
They're not actual machine code: .pyc files hold Python bytecode, which runs on the Python Virtual Machine (PVM), not directly on your CPU. The PVM on ARM64 can happily read and run bytecode made on x86_64—no problem there. The format is the same across platforms.
The real "risk" isn't what you might think: It's not about the board running some evil x86_64 instructions (it literally can't). Instead, the issue is that these old .pyc files are just extra baggage that could hide bugs. If something went wrong in your build and you end up with mismatched .pyc files that don't match your .py source code, you'll get weird, head-scratching errors later.
Bottom line on security: They won't let hackers take over your board like a bad binary might. But from a "is my software solid?" angle, they're like a mismatched puzzle piece—wrong and potentially misleading.2. Will They Get Updated on the ARM64 Board? (The Big Question)Yeah, they'll probably get rebuilt from scratch, and that's the key takeaway here. Python decides whether to use an existing .pyc or make a new one based on a few checks:
Does the .pyc file even exist?
Does its "magic number" match? (That's a little 4-byte tag at the start that says which Python version made it.) If you used the same Python version (like 3.9) on both machines, this is fine.
Is the .pyc newer than the .py source file? Timestamps are where things get messy, especially with your board's off-kilter clock.
Here's how it plays out:
Scenario A: Board's clock is right (or ahead of your build time). The .pyc looks old compared to the .py (which the board thinks is "recent"). Python says, "Outdated—time to remake it."
Scenario B: Board's clock is behind your build time (the sneaky one). From the board's view, the .pyc was made in the "future," so it's newer than the .py. Python goes, "Cool, I'll use this one," and skips regenerating. Boom—your code runs on outdated bytecode that doesn't match what you shipped. Debugging nightmare.
Pro tip: Don't trust timestamps for reliable builds. Always wipe the slate clean to avoid these gotchas.3. How Does the Wrong System Time Mess Things Up?Like I mentioned, a screwy clock can trick Python's "is this fresh?" check. It might make it reuse stale .pyc files when it shouldn't, or force unnecessary rebuilds. Either way, it's a recipe for frustration.What You Should Do: Tips and FixesYou're smart to worry about this—it's a common pitfall. Here's how to handle it: