39 lines
1.5 KiB
Go
39 lines
1.5 KiB
Go
// Copyright 2019 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package cpuid provides basic functionality for creating and adjusting CPU
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// feature sets.
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//
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// To use FeatureSets, one should start with an existing FeatureSet (either a
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// known platform, or HostFeatureSet()) and then add, remove, and test for
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// features as desired.
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//
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// For example: on x86, test for hardware extended state saving, and if
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// we don't have it, don't expose AVX, which cannot be saved with fxsave.
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//
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// if !HostFeatureSet().HasFeature(X86FeatureXSAVE) {
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// exposedFeatures.Remove(X86FeatureAVX)
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// }
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package cpuid
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// Feature is a unique identifier for a particular cpu feature. We just use an
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// int as a feature number on x86 and arm64.
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//
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// On x86, features are numbered according to "blocks". Each block is 32 bits, and
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// feature bits from the same source (cpuid leaf/level) are in the same block.
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//
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// On arm64, features are numbered according to the ELF HWCAP definition.
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// arch/arm64/include/uapi/asm/hwcap.h
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type Feature int
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