github.com/geraldss/go/src@v0.0.0-20210511222824-ac7d0ebfc235/runtime/os_linux_arm.go (about)

     1  // Copyright 2009 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  package runtime
     6  
     7  import "internal/cpu"
     8  
     9  const (
    10  	_HWCAP_VFP   = 1 << 6  // introduced in at least 2.6.11
    11  	_HWCAP_VFPv3 = 1 << 13 // introduced in 2.6.30
    12  )
    13  
    14  func checkgoarm() {
    15  	// On Android, /proc/self/auxv might be unreadable and hwcap won't
    16  	// reflect the CPU capabilities. Assume that every Android arm device
    17  	// has the necessary floating point hardware available.
    18  	if GOOS == "android" {
    19  		return
    20  	}
    21  	if goarm > 5 && cpu.HWCap&_HWCAP_VFP == 0 {
    22  		print("runtime: this CPU has no floating point hardware, so it cannot run\n")
    23  		print("this GOARM=", goarm, " binary. Recompile using GOARM=5.\n")
    24  		exit(1)
    25  	}
    26  	if goarm > 6 && cpu.HWCap&_HWCAP_VFPv3 == 0 {
    27  		print("runtime: this CPU has no VFPv3 floating point hardware, so it cannot run\n")
    28  		print("this GOARM=", goarm, " binary. Recompile using GOARM=5 or GOARM=6.\n")
    29  		exit(1)
    30  	}
    31  }
    32  
    33  func archauxv(tag, val uintptr) {
    34  	switch tag {
    35  	case _AT_HWCAP:
    36  		cpu.HWCap = uint(val)
    37  	case _AT_HWCAP2:
    38  		cpu.HWCap2 = uint(val)
    39  	}
    40  }
    41  
    42  func osArchInit() {}
    43  
    44  //go:nosplit
    45  func cputicks() int64 {
    46  	// Currently cputicks() is used in blocking profiler and to seed fastrand().
    47  	// nanotime() is a poor approximation of CPU ticks that is enough for the profiler.
    48  	return nanotime()
    49  }