Nico Weber 8a01be4849 Kernel: Add some CPU feature flags related to TSC ... In case we want to rely more on TSC in time keeping in the future, idk This adds: - RDTSCP, for when the RDTSCP instruction is available - CONSTANT_TSC, for when the TSC has a constant frequency, invariant under things like the CPU boosting its frequency. - NONSTOP_TSC, for when the TSC doesn't pause when the CPU enters sleep states. AMD cpus and newer intel cpus set the INVSTC bit (bit 8 in edx of extended cpuid 0x8000000008), which implies both CONSTANT_TSC and NONSTOP_TSC. Some older intel processors have CONSTANT_TSC but not NONSTOP_TSC; this is set based on cpu model checks. There isn't a ton of documentation on this, so this follows Linux terminology and http://blog.tinola.com/?e=54 CONSTANT_TSC: 39b3a79105 NONSTOP_TSC: 40fb17152c qemu disables invtsc (bit 8 in edx of extended cpuid 0x8000000008) by default even if the host cpu supports it. It can be enabled by running with `SERENITY_QEMU_CPU=host,migratable=off` set.		2020-10-08 10:00:39 +02:00
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i386	Kernel: Add some CPU feature flags related to TSC	2020-10-08 10:00:39 +02:00
PC	AK: Rename KB, MB, GB to KiB, MiB, GiB	2020-08-16 16:33:28 +02:00