| // 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 |
| _AT_HWCAP = 16 // 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 fastrand1(). |
| // nanotime() is a poor approximation of CPU ticks that is enough for the profiler. |
| // randomNumber provides better seeding of fastrand1. |
| return nanotime() + int64(randomNumber) |
| } |