.\" Copyright (c) 2007 Joseph Koshy. All rights reserved.
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.\" $FreeBSD$
.\"
.Dd November 25, 2007
.Dt PMC_ATTACH 3
.Os
.Sh NAME
.Nm pmc_attach ,
.Nm pmc_detach
.Nd attaching and detaching process scope PMCs to target processes
.Sh LIBRARY
.Lb libpmc
.Sh SYNOPSIS
.In pmc.h
.Ft int
.Fn pmc_attach "pmc_id_t pmcid" "pid_t pid"
.Ft int
.Fn pmc_detach "pmc_id_t pmcid" "pid_t pid"
.Sh DESCRIPTION
These functions control the set of target processes tracked by a
process scope PMC.
.Pp
Function
.Fn pmc_attach
is used to attach a process scope PMC specified by argument
.Fa pmcid
to a target process specified by argument
.Fa pid .
Argument
.Fa pid
may be zero to denote the current process.
If the PMC was allocated with modifier
.Dv PMC_F_DESCENDANTS ,
the PMC will additionally attach to current and future descendents of
the specified target process.
The PMC should be in a quiescent state (i.e., not running).
.Pp
Function
.Fn pmc_detach
is used to detach a process scope PMC specified by argument
.Fa pmcid
from a process specified by argument
.Fa pid .
Argument
.Fa pid
may be zero to denote the current process.
.Sh RETURN VALUES
.Rv -std
.Sh ERRORS
A call to function
.Fn pmc_attach
may fail with the following errors:
.Bl -tag -width Er
.It Bq Er EBUSY
Argument
.Fa pmcid
specified a PMC that was not in a quiescent state.
.It Bq Er EBUSY
The target process specified by function
.Fa pmc_attach
is being tracked by another process scope PMC that uses the same PMC
hardware resources.
.It Bq Er EEXIST
The target process is already being tracked by the specified PMC.
.It Bq Er EINVAL
Argument
.Fa pmcid
specified a PMC with system scope.
.It Bq Er EINVAL
Argument
.Fa pid
specified an illegal process id.
.It Bq Er EINVAL
The current process does not own a PMC with the handle specified in
argument
.Fa pmcid .
.It Bq Er EPERM
The caller lacked the privilege needed to attach PMCs to
the specified target process.
.It Bq Er EPERM
(i386 and amd64 architectures) The PMC specified by argument
.Fa pmcid
has been setup to allow the use of the RDPMC instruction for
self measurement.
.It Bq Er ESRCH
The current process does not own any PMCs.
.It Bq Er ESRCH
The process specified by argument
.Fa pid
did not exist.
.El
.Pp
A call to function
.Fn pmc_detach
may fail with the following errors:
.Bl -tag -width Er
.It Bq Er EINVAL
Argument
.Fa pmcid
specified a PMC with system scope.
.It Bq Er EINVAL
Argument
.Fa pid
specified an illegal process id.
.It Bq Er EINVAL
The current process does not own a PMC with the handle specified in
argument
.Fa pmcid .
.It Bq Er EINVAL
The specified PMC was not attached to the target process.
.It Bq Er ESRCH
The current process does not own any PMCs.
.It Bq Er ESRCH
The process specified by argument
.Fa pid
is not being monitored by
.Xr hwpmc 4 .
.It Bq Er ESRCH
The process specified by argument
.Fa pid
did not exist.
.El
.Sh SEE ALSO
.Xr pmc 3 ,
.Xr pmc_start 3 ,
.Xr pmc_stop 3 ,
.Xr hwpmc 4
