Linked by Thom Holwerda on Wed 3rd Jan 2018 00:42 UTC
Intel

A fundamental design flaw in Intel's processor chips has forced a significant redesign of the Linux and Windows kernels to defang the chip-level security bug.

Programmers are scrambling to overhaul the open-source Linux kernel's virtual memory system. Meanwhile, Microsoft is expected to publicly introduce the necessary changes to its Windows operating system in an upcoming Patch Tuesday: these changes were seeded to beta testers running fast-ring Windows Insider builds in November and December.

Crucially, these updates to both Linux and Windows will incur a performance hit on Intel products. The effects are still being benchmarked, however we're looking at a ballpark figure of five to 30 per cent slow down, depending on the task and the processor model. More recent Intel chips have features - such as PCID - to reduce the performance hit.

That's one hell of a bug.

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RE[2]: Overhyped
by Carewolf on Wed 3rd Jan 2018 12:32 UTC in reply to "RE: Overhyped"
Carewolf
Member since:
2005-09-08

"Note that the insane hackery to avoid this non-issue adds significant overhead to kernel system calls; ironically, making the performance of monolithic kernels worse than the performance of micro-kernels (while still providing inferior security than micro-kernels). The insane hackery doesn't entirely fix the "problem" either (a small part of kernel must remain mapped, and an attacker can still find out where in kernel space that small part of the kernel is and use this information to infer where the rest of the kernel is).

Please do not claim bogus. Microkernels fixed against this defect will in fact take a higher hit than a monolithic kernel.
"
No. Let me put is like this: Microkernels are already talking a similar hit as their context switches are from user to user, now Macrokernels get a similar hit by having to dump the virtual tables before going to user mode, just like each user's table are dropped when moving to another user.

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