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 struct:
typedef struct {
int level; /* CPUID level */
uint32_t data[4];
} cpuctl_cpuid_args_t;
The level field indicates the CPUID level to retrieve
information for, while the data field is used to
store the received CPUID data.
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.
BUGS¶
Yes, probably, report if any.
AUTHORS¶
The
cpuctl module and this manual page were written by
Stanislav Sedov
⟨stas@FreeBSD.org⟩.
