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v0.8.1
https://github.com/torvalds/linux
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Tip revision: d1fdb6d8f6a4109a4263176c84b899076a5f8008 authored by Linus Torvalds on 09 June 2019, 03:24:46 UTC
Linux 5.2-rc4
Tip revision: d1fdb6d
msr.c
// SPDX-License-Identifier: GPL-2.0
#include <math.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/timeb.h>
#include <sched.h>
#include <errno.h>


int main(int argc, char **argv) {
	int cpu, fd;
	long long msr;
	char msr_file_name[64];

	if (argc != 2)
		return 1;

	errno = 0;
	cpu = strtol(argv[1], (char **) NULL, 10);

	if (errno)
		return 1;

	sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
	fd = open(msr_file_name, O_RDONLY);

	if (fd == -1) {
		perror("Failed to open");
		return 1;
	}

	pread(fd, &msr,  sizeof(msr), 0x199);

	printf("msr 0x199: 0x%llx\n", msr);
	return 0;
}
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