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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package runtime
import "unsafe"
const (
_AT_PLATFORM = 15 // introduced in at least 2.6.11
_HWCAP_VFP = 1 << 6 // introduced in at least 2.6.11
_HWCAP_VFPv3 = 1 << 13 // introduced in 2.6.30
)
var randomNumber uint32
var armArch uint8 = 6 // we default to ARMv6
var hwcap uint32 // set by setup_auxv
func checkgoarm() {
if goarm > 5 && hwcap&_HWCAP_VFP == 0 {
print("runtime: this CPU has no floating point hardware, so it cannot run\n")
print("this GOARM=", goarm, " binary. Recompile using GOARM=5.\n")
exit(1)
}
if goarm > 6 && hwcap&_HWCAP_VFPv3 == 0 {
print("runtime: this CPU has no VFPv3 floating point hardware, so it cannot run\n")
print("this GOARM=", goarm, " binary. Recompile using GOARM=5.\n")
exit(1)
}
}
func archauxv(tag, val uintptr) {
switch tag {
case _AT_RANDOM:
// sysargs filled in startupRandomData, but that
// pointer may not be word aligned, so we must treat
// it as a byte array.
randomNumber = uint32(startupRandomData[4]) | uint32(startupRandomData[5])<<8 |
uint32(startupRandomData[6])<<16 | uint32(startupRandomData[7])<<24
case _AT_PLATFORM: // v5l, v6l, v7l
t := *(*uint8)(unsafe.Pointer(val + 1))
if '5' <= t && t <= '7' {
armArch = t - '0'
}
case _AT_HWCAP: // CPU capability bit flags
hwcap = uint32(val)
}
}
//go:nosplit
func cputicks() int64 {
// Currently cputicks() is used in blocking profiler and to seed fastrand().
// nanotime() is a poor approximation of CPU ticks that is enough for the profiler.
// randomNumber provides better seeding of fastrand.
return nanotime() + int64(randomNumber)
}
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