golang.org/x/sys@v0.20.1-0.20240517151509-673e0f94c16d/cpu/proc_cpuinfo_linux.go (about)

     1  // Copyright 2022 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build linux && arm64
     6  
     7  package cpu
     8  
     9  import (
    10  	"errors"
    11  	"io"
    12  	"os"
    13  	"strings"
    14  )
    15  
    16  func readLinuxProcCPUInfo() error {
    17  	f, err := os.Open("/proc/cpuinfo")
    18  	if err != nil {
    19  		return err
    20  	}
    21  	defer f.Close()
    22  
    23  	var buf [1 << 10]byte // enough for first CPU
    24  	n, err := io.ReadFull(f, buf[:])
    25  	if err != nil && err != io.ErrUnexpectedEOF {
    26  		return err
    27  	}
    28  	in := string(buf[:n])
    29  	const features = "\nFeatures	: "
    30  	i := strings.Index(in, features)
    31  	if i == -1 {
    32  		return errors.New("no CPU features found")
    33  	}
    34  	in = in[i+len(features):]
    35  	if i := strings.Index(in, "\n"); i != -1 {
    36  		in = in[:i]
    37  	}
    38  	m := map[string]*bool{}
    39  
    40  	initOptions() // need it early here; it's harmless to call twice
    41  	for _, o := range options {
    42  		m[o.Name] = o.Feature
    43  	}
    44  	// The EVTSTRM field has alias "evstrm" in Go, but Linux calls it "evtstrm".
    45  	m["evtstrm"] = &ARM64.HasEVTSTRM
    46  
    47  	for _, f := range strings.Fields(in) {
    48  		if p, ok := m[f]; ok {
    49  			*p = true
    50  		}
    51  	}
    52  	return nil
    53  }