github.com/varialus/godfly@v0.0.0-20130904042352-1934f9f095ab/src/pkg/runtime/os_linux_arm.c (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  #include "runtime.h"
     6  #include "defs_GOOS_GOARCH.h"
     7  #include "os_GOOS.h"
     8  #include "../../cmd/ld/textflag.h"
     9  
    10  #define AT_NULL		0
    11  #define AT_PLATFORM	15 // introduced in at least 2.6.11
    12  #define AT_HWCAP	16 // introduced in at least 2.6.11
    13  #define AT_RANDOM	25 // introduced in 2.6.29
    14  #define HWCAP_VFP	(1 << 6) // introduced in at least 2.6.11
    15  #define HWCAP_VFPv3	(1 << 13) // introduced in 2.6.30
    16  static uint32 runtime·randomNumber;
    17  uint8  runtime·armArch = 6;	// we default to ARMv6
    18  uint32 runtime·hwcap;	// set by setup_auxv
    19  uint8  runtime·goarm;	// set by 5l
    20  
    21  void
    22  runtime·checkgoarm(void)
    23  {
    24  	if(runtime·goarm > 5 && !(runtime·hwcap & HWCAP_VFP)) {
    25  		runtime·printf("runtime: this CPU has no floating point hardware, so it cannot run\n");
    26  		runtime·printf("this GOARM=%d binary. Recompile using GOARM=5.\n", runtime·goarm);
    27  		runtime·exit(1);
    28  	}
    29  	if(runtime·goarm > 6 && !(runtime·hwcap & HWCAP_VFPv3)) {
    30  		runtime·printf("runtime: this CPU has no VFPv3 floating point hardware, so it cannot run\n");
    31  		runtime·printf("this GOARM=%d binary. Recompile using GOARM=6.\n", runtime·goarm);
    32  		runtime·exit(1);
    33  	}
    34  }
    35  
    36  #pragma textflag NOSPLIT
    37  void
    38  runtime·setup_auxv(int32 argc, byte **argv)
    39  {
    40  	byte **envp;
    41  	byte *rnd;
    42  	uint32 *auxv;
    43  	uint32 t;
    44  
    45  	// skip envp to get to ELF auxiliary vector.
    46  	for(envp = &argv[argc+1]; *envp != nil; envp++)
    47  		;
    48  	envp++;
    49  	
    50  	for(auxv=(uint32*)envp; auxv[0] != AT_NULL; auxv += 2) {
    51  		switch(auxv[0]) {
    52  		case AT_RANDOM: // kernel provided 16-byte worth of random data
    53  			if(auxv[1]) {
    54  				rnd = (byte*)auxv[1];
    55  				runtime·randomNumber = rnd[4] | rnd[5]<<8 | rnd[6]<<16 | rnd[7]<<24;
    56  			}
    57  			break;
    58  		case AT_PLATFORM: // v5l, v6l, v7l
    59  			if(auxv[1]) {
    60  				t = *(uint8*)(auxv[1]+1);
    61  				if(t >= '5' && t <= '7')
    62  					runtime·armArch = t - '0';
    63  			}
    64  			break;
    65  		case AT_HWCAP: // CPU capability bit flags
    66  			runtime·hwcap = auxv[1];
    67  			break;
    68  		}
    69  	}
    70  }
    71  
    72  #pragma textflag NOSPLIT
    73  int64
    74  runtime·cputicks(void)
    75  {
    76  	// Currently cputicks() is used in blocking profiler and to seed runtime·fastrand1().
    77  	// runtime·nanotime() is a poor approximation of CPU ticks that is enough for the profiler.
    78  	// runtime·randomNumber provides better seeding of fastrand1.
    79  	return runtime·nanotime() + runtime·randomNumber;
    80  }