Spectre & Meltdown

On Jan 13, 2018 11:36 AM, "Paul Koning via cctalk" <cctalk at classiccmp.org> wrote: wrote: fixes. This is now standard and the delays are defined... fixing-security-vulnerability-chips-52122993 AMD and PowerPC but nothing from them either. IBM won't tell the world (it will tell customers, but I am not a customer) if and how it affects Z. There are two bugs that are largely unrelated other than the fact they both start from speculative execution. One is "Meltdown" which is specific to Intel as far as is known. The other is "Spectre" which is a pretty much unavoidable side effect of the existence of speculative execution and appears to apply to multiple architectures. There may be variations; I assume some designs have much shorter speculation pipelines than others and if so would be less affected. Meltdown has a software workaround (it could also be fixed in future chips by changing how speculative loads work, to match what other companies did). Sorta. A 10% performance hit and tthe workaround is extensive. So it's forcing everyone to eat a shit sandwich to work around it. Spectre needs software fixes, possibly along with microcode changes (for machines that have such a thing). You're likely to hear more when the fixes are available; it would not make sense to have much discussion before then for the reason you mentioned at the top. Spectre for Intel requires microcode changes and OS level changes to cope, and changes to the compiler for retpoline support. The os guys need to talk about their piece a lot, so it needs disclosure as well... it's a smaller shit sandwich in terms of performance hit... Warner