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#ident "$Id: wrmsr.c,v 1.3 2004/07/20 15:54:59 hpa Exp $"
/* ----------------------------------------------------------------------- *
*
* Copyright 2000 Transmeta Corporation - All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139,
* USA; either version 2 of the License, or (at your option) any later
* version; incorporated herein by reference.
*
* ----------------------------------------------------------------------- */
/*
* wrmsr.c
*
* Utility to write to an MSR.
*/
#include <errno.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <getopt.h>
#include <inttypes.h>
#include <sys/types.h>
#include "version.h"
struct option long_options[] = {
{ "help", 0, 0, 'h' },
{ "version", 0, 0, 'V' },
{ "processor", 1, 0, 'p' },
{ "cpu", 1, 0, 'p' },
{ 0, 0, 0, 0 }
};
const char *program;
void usage(void)
{
fprintf(stderr, "Usage: %s [options] regno value...\n"
" --help -h Print this help\n"
" --version -V Print current version\n"
" --processor # -p Select processor number (default 0)\n"
, program);
}
int main(int argc, char *argv[])
{
uint32_t reg;
uint64_t data;
int fd;
int c;
int cpu = 0;
unsigned long arg;
char *endarg;
char msr_file_name[64];
program = argv[0];
while ( (c = getopt_long(argc,argv,"hVp:",long_options,NULL)) != - 1 ) {
switch( c ) {
case 'h':
usage();
exit(0);
case 'V':
fprintf(stderr, "%s: version %s\n", program, VERSION_STRING);
exit(0);
case 'p':
arg = strtoul(optarg, &endarg, 0);
if ( *endarg || arg > 255 ) {
usage();
exit(127);
}
cpu = (int)arg;
break;
default:
usage();
exit(127);
}
}
if ( optind > argc-2 ) {
/* Should have at least two arguments */
usage();
exit(127);
}
reg = strtoul(argv[optind++], NULL, 0);
sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
fd = open(msr_file_name, O_WRONLY);
if ( fd < 0 ) {
if ( errno == ENXIO ) {
fprintf(stderr, "wrmsr: No CPU %d\n", cpu);
exit(2);
} else if ( errno == EIO ) {
fprintf(stderr, "wrmsr: CPU %d doesn't support MSRs\n", cpu);
exit(3);
} else {
perror("wrmsr:open");
exit(127);
}
}
while ( optind < argc ) {
data = strtoull(argv[optind++], NULL, 0);
if ( pwrite(fd, &data, sizeof data, reg) != sizeof data ) {
perror("wrmsr:pwrite");
exit(127);
}
}
close(fd);
exit(0);
}
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