January 4, 2026
Paging wars, spicy cores
Linear Address Spaces: Unsafe at any speed
Old-school memory maps roasted, but fans yell “don’t break my stuff”
TLDR: A veteran engineer says the way computers map memory is outdated and dangerously complex, urging an object-based rethink. Commenters clap back: preserving old software matters, real hardware still needs addresses, and some security features already help—sparking a lively split between “future now” and “don’t break what works.”
ACM’s Queue asked for feedback on a redesign and got a full-on tech soap opera. In a fiery essay, systems veteran Poul-Henning Kamp claims the way computers track memory—one big “line” of addresses—is “unsafe at any speed.” He praises Apple’s M1 chip for sipping power but says modern memory mapping is a five-layer lasagna of complexity. His pitch: ditch the old “one giant line of memory” and think in objects, like boxes you label and store, not a single endless shelf.
Cue the comment brawl. The loudest chorus: backwards compatibility or bust. User tliltocatl quips that old software still runs the world, so don’t nuke the past. Security-minded btdmaster counters that hardware is already nudging toward safer designs—think “shadow stacks” (extra bookkeeping to prevent sneaky jumps) and control-flow integrity (don’t let code run off the rails). Pragmatists like irdc throw cold water: if your “objects” are huge, how do you even find them without mega maps? mikewarot drops the mic: somewhere, a real physical address still has to exist.
Meanwhile, the crowd giggles at Kamp’s zingers—“We don’t talk about Thumb-2” becomes a meme, and the S/360 RISC joke earns a chorus of “ahaha so true.” It’s high drama, low jargon, and maximum vibes: modernize memory or protect the past? The thread picks both, loudly.
Key Points
- •Modern ARM and x86-64 architectures share complexity in translating linear virtual addresses to linear physical addresses.
- •Deep page-table hierarchies (up to five levels) and multiple page sizes introduce performance overhead and numerous exception paths.
- •Linear address spaces persist primarily due to backward compatibility with older systems lacking virtual memory.
- •Operating systems typically implement abstract object stores over linear memory, then map virtual to physical memory within architectural limits.
- •The author highlights alternative approaches and cites work emulating the Rational R1000/s400, implying different architectural models are possible.