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):
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 disabled).
- [
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.