DT(4) | Device Drivers Manual | DT(4) |
dt
— dynamic
tracer
pseudo-device dt
System and application tracing can happen in the kernel. It has to be configured and enabled through the ioctl(2) interface exposed by the pseudo-device /dev/dt.
This device can only be opened when the kern.allowdt sysctl(2) variable is set.
The ioctl(2) command codes below
are defined in
<dev/dt/dtvar.h>
.
DTIOCGPLIST
struct dtioc_probe *dtprstruct dtioc_probe { size_t dtpr_size; struct dtioc_probe_info *dtpr_probes; };
If dtpr_size is non-zero, as many probes
as possible that can fit into this size will be copied into the supplied
buffer. On exit, dtpr_size is always set to the
total size required to hold all probe entries (i.e., it is set to
sizeof(struct dtioc_probe_info) *
dt_nprobes
).
DTIOCGSTATS
struct dtioc_stat *dtststruct dtioc_stat { uint64_t dtst_readevt; uint64_t dtst_dropevt; };
DTIOCRECORD
int onDTIOCPRBENABLE
struct dtioc_req *dtrqstruct dtioc_req { uint32_t dtrq_pbn; struct dt_filter dtrq_filter; uint32_t dtrq_rate; uint64_t dtrq_evtflags; };
An open of /dev/dt will fail if:
The dt
dynamic tracing mechanism first
appeared in OpenBSD 6.7.
December 2, 2020 | OpenBSD-current |