About 24 hours prior to its collision, NASA’s Double Asteroid Redirect Test (DART) probe performed its last course correction based on commands sent by ground controllers. “It’s pointed to within a football field of the central body,” said Bobby Braun of the Johns Hopkins Applied Physics Lab (APL). “That last maneuver was spot-on.”
Enlarge / A second-generation Epyc server chip from AMD, one that may have been running 2002-era Linux code slowing it down. (credit: Getty Images)
AMD has come a long way since 2002, but the Linux kernel still treats modern Threadrippers like Athlon-era systems—at least in one potentially lag-inducing respect.
AMD engineer Prateek Nayak recently submitted a patch to Linux’s processor idle drivers that would “skip dummy wait for processors based on the Zen microarchitecture.” When ACPI support was added to the Linux kernel in 2002—written by Andy Grover, committed by Linus Torvalds—it included a “dummy wait op.” The system essentially read data with no purpose other than delaying the next instruction until the CPU could…
The CHERI
architecture is the product of a research program to extend common
CPU architectures in a way that prevents many types of memory-related bugs (and
vulnerabilities). At the 2022 GNU Tools Cauldron,
Alex Coplan and Szabolcs Nagy described the work that has been done to
bring GCC and the GNU C Library (glibc) to this architecture. CHERI is a fundamentally
different approach to how memory is accessed, and supporting it properly is anything
but a trivial task.
Enlarge / One of the last images from DART. (credit: NASA/APL)