4 ms·
Direct link to a description of the fix: https://support.google.com/faqs/answer/7625886 https://support.google.com/faqs/answer/7625886 Someone on SO trying to
by kyrra 9y ago
Direct link to a description of the fix: https://support.google.com/faqs/answer/7625886 https://support.google.com/faqs/answer/7625886
Someone on SO trying to explain it another way: https://stackoverflow.com/a/48099456 https://stackoverflow.com/a/48099456
Some interesting discussion about how this patch isn't a 100% fix for Skylake processors (at least that's my understanding): https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1577670.html https://www.mail-archive.com/linux-kernel@vger.kernel.org/ms...
- x0x0 9y agoI don't understand how this fix can possibly be so performant. The speculative executions must be doing something positive, right? It seems like it should never hurt (ignoring security, obv). So how can disabling it not hurt? Thanks for the stackover flow link!
- bradleyjkemp 9y agoSounds like they're just forcing the CPU to use a different (less vulnerable) type of predictor. It's the branch target predictor that's vulnerable so instead of using a branch instruction the compiler now adds a mini stack frame (with the return address as the place we want to jump to) and then "returns". The CPU now happily predicts the target using the non-vulnerable stack predictor and does do speculative execution.