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CPUCTL(4)	       FreeBSD Kernel Interfaces Manual		     CPUCTL(4)

NAME
     cpuctl -- cpuctl pseudo device

SYNOPSIS
     To	compile	this driver into the kernel, place the following lines in your
     kernel configuration file:

	   device cpuctl

     Alternatively, to load the	driver as a module at boot time, place the
     following in loader.conf(5):

	   cpuctl_load="YES"

DESCRIPTION
     The special device	/dev/cpuctl presents interface to the system CPU.  It
     provides functionality to retrieve	CPUID information, read/write machine
     specific registers	(MSR) and perform CPU firmware updates.

     For each CPU present in the system, the special device /dev/cpuctl%d with
     the appropriate index will	be created.  For multicore CPUs	such a special
     device will be created for	each core.

     Currently,	only i386 and amd64 processors are supported.

IOCTL INTERFACE
     All of the	supported operations are invoked using the ioctl(2) system
     call.  Currently, the following ioctls are	defined:

     CPUCTL_RDMSR cpuctl_msr_args_t *args

     CPUCTL_WRMSR cpuctl_msr_args_t *args
			 Read/write CPU	machine	specific register.  The
			 cpuctl_msr_args_t structure is	defined	in
			 <sys/cpuctl.h>	as:

			 typedef struct	{
				 int		 msr;	 /* MSR	to read	*/
				 uint64_t	 data;
			 } cpuctl_msr_args_t;

     CPUCTL_MSRSBIT cpuctl_msr_args_t *args

     CPUCTL_MSRCBIT cpuctl_msr_args_t *args
			 Set/clear MSR bits according to the mask given	in the
			 data field.

     CPUCTL_CPUID cpuctl_cpuid_args_t *args
			 Retrieve CPUID	information.  Arguments	are supplied
			 in the	following structure:

			 typedef struct	{
				 int		 level;		 /* CPUID level	*/
				 uint32_t	 data[4];
			 } cpuctl_cpuid_args_t;
			 It is equivalent to the CPUCTL_CPUID_COUNT request
			 with level_type set to	0.

     CPUCTL_CPUID_COUNT	cpuctl_cpuid_count_args_t *args
			 Retrieve CPUID	information.  Arguments	are supplied
			 in the	following structure:

			 typedef struct	{
				 int		 level;		 /* CPUID level	*/
				 int		 level_type;	 /* CPUID level	type */
				 uint32_t	 data[4];
			 } cpuctl_cpuid_count_args_t;
			 The level field indicates the CPUID level to
			 retrieve, it is loaded	into the %eax register before
			 the CPUID instruction is executed, The	level_type
			 field indicates the CPUID level type to retrieve, it
			 is loaded into	the %ecx register.

			 The data field	is used	to store the received CPUID
			 data.	That is, data[0] contains the value of %eax
			 register after	the CPUID instruction is executed,
			 data[1] is for	%ebx, data[2] for %ecx,	and data[3]
			 for %edx.

     CPUCTL_UPDATE cpuctl_update_args_t	*args
			 Update	CPU firmware (microcode).  The structure is
			 defined in <sys/cpuctl.h> as:

			 typedef struct	{
				 void	 *data;
				 size_t	 size;
			 } cpuctl_update_args_t;

			 The data field	should point to	the firmware image of
			 size size.

     For additional information	refer to cpuctl.h.

RETURN VALUES
     [ENXIO]		The operation requested	is not supported by the	device
			(e.g., unsupported architecture	or the CPU is dis-
			abled).

     [EINVAL]		Incorrect request was supplied,	or microcode image is
			not correct.

     [ENOMEM]		No physical memory was available to complete the
			request.

     [EFAULT]		The firmware image address points outside the process
			address	space.

FILES
     /dev/cpuctl

SEE ALSO
     hwpmc(4), cpucontrol(8)

HISTORY
     The cpuctl	driver first appeared in FreeBSD 7.2.

AUTHORS
     The cpuctl	module and this	manual page were written by Stanislav Sedov
     <stas@FreeBSD.org>.

BUGS
     Yes, probably, report if any.

FreeBSD	10.1			 June 20, 2014			  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | IOCTL INTERFACE | RETURN VALUES | FILES | SEE ALSO | HISTORY | AUTHORS | BUGS

Want to link to this manual page? Use this URL:
<http://www.freebsd.org/cgi/man.cgi?query=cpuctl&sektion=4&manpath=FreeBSD+10.1-RELEASE>

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