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The CPU won't speculatively execute past certain instructions. AFAIK it's up to (e.g.) the SSD driver to prevent the CPU from speculatively sending commands to
by panic 11y ago
The CPU won't speculatively execute past certain instructions. AFAIK it's up to (e.g.) the SSD driver to prevent the CPU from speculatively sending commands to the drive.
- gliptic 11y agoIt's not up to the SSD driver. The SSD driver will not see any effects of speculatively executed code and there's no way the CPU could speculatively send commands to the drive.
- panic 11y agoWhat if you're communicating with the SSD via DMA? Don't you have to make sure that the writes aren't speculatively executed?
- daemin 11y agoBecause DMA occurs when the CPU writes to memory, and as my comment above states this occurs after the condition is evaluated and the jump instruction (not) taken. Speculative execution is purely within the CPU and doesn't leak out - except in the case of worse than ideal performance.