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authorAndreas Sandberg <andreas@sandberg.pp.se>2013-09-25 12:24:26 +0200
committerAndreas Sandberg <andreas@sandberg.pp.se>2013-09-25 12:24:26 +0200
commit599b59b38754c764aced7edf553c2dea846d3cd8 (patch)
tree164e5d2216f789d00baea2efcceaf4bdc3041a4b /src/doc
parentcd9cd85ce9b0f3905ecfcd843d128b0fd754871c (diff)
downloadgem5-599b59b38754c764aced7edf553c2dea846d3cd8.tar.xz
kvm: Initial x86 support
This changeset adds support for KVM on x86. Full support is split across a number of commits since some features are relatively complex. This changeset includes support for: * Integer state synchronization (including segment regs) * CPUID (gem5's CPUID values are inserted into KVM) * x86 legacy IO (remapped and handled by gem5's memory system) * Memory mapped IO * PCI * MSRs * State dumping Most of the functionality is fairly straight forward. There are some quirks to support PCI enumerations since this is done in the TLB(!) in the simulated CPUs. We currently replicate some of that code. Unlike the ARM implementation, the x86 implementation of the virtual CPU does not use the cycles hardware counter. KVM on x86 simulates the time stamp counter (TSC) in the kernel. If we just measure host cycles using perfevent, we might end up measuring a slightly different number of cycles. If we don't get the cycle accounting right, we might end up rewinding the TSC, with all kinds of chaos as a result. An additional feature of the KVM CPU on x86 is extended state dumping. This enables Python scripts controlling the simulator to request dumping of a subset of the processor state. The following methods are currenlty supported: * dumpFpuRegs * dumpIntRegs * dumpSpecRegs * dumpDebugRegs * dumpXCRs * dumpXSave * dumpVCpuEvents * dumpMSRs Known limitations: * M5 ops are currently not supported. * FPU synchronization is not supported (only affects CPU switching). Both of the limitations will be addressed in separate commits.
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