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mi_switch.9: Remove cpu_switch, cpu_throw

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cpu_machdep.9 was added to document cpu_*, but cpu_switch and cpu_throw
were already documented in mi_switch.9, and MLINKed.  cpu_machdep.9
seems like the correct place for this, so remove them from mi_switch.9.

Some of the removed text was stale, although there are few notes that
ought to be added to cpu_machdep.9 in a future commit.

Reported by:	tools/pkgbase/metalog_reader.lua
Reviewed by:	jhb
Sponsored by:	The FreeBSD Foundation
Fixes: 9c87cbbcaaed ("cpu_machdep.9: New manpage describing the semantics of several cpu_*")
Differential Revision: https://reviews.freebsd.org/D48360

(cherry picked from commit f73c9b5da190954a81e9e70e2caa8e9168623bfd)
This commit is contained in:
Ed Maste 2025-01-07 11:04:00 -05:00 committed by John Baldwin
parent dab1feb75e
commit 0cfebe47d9
2 changed files with 4 additions and 66 deletions
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2
share/man/man9/Makefile
View file

@ -1592,8 +1592,6 @@ MLINKS+=microuptime.9 binuptime.9 \
microuptime.9 getsbinuptime.9 \
microuptime.9 nanouptime.9 \
microuptime.9 sbinuptime.9
MLINKS+=mi_switch.9 cpu_switch.9 \
mi_switch.9 cpu_throw.9
MLINKS+=mod_cc.9 CCV.9 \
mod_cc.9 DECLARE_CC_MODULE.9
MLINKS+=mtx_pool.9 mtx_pool_alloc.9 \

68
share/man/man9/mi_switch.9
View file

@ -31,23 +31,17 @@
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd January 9, 2023
.Dd January 7, 2025
.Dt MI_SWITCH 9
.Os
.Sh NAME
.Nm mi_switch ,
.Nm cpu_switch ,
.Nm cpu_throw
.Nm mi_switch
.Nd switch to another thread context
.Sh SYNOPSIS
.In sys/param.h
.In sys/proc.h
.Ft void
.Fn mi_switch "int flags"
.Ft void
.Fn cpu_switch "struct thread *oldtd" "struct thread *newtd" "struct mtx *lock"
.Ft void
.Fn cpu_throw "struct thread *oldtd" "struct thread *newtd"
.Sh DESCRIPTION
The
.Fn mi_switch
@ -168,63 +162,9 @@ running thread
.Fa oldtd
to the chosen thread
.Fa newtd .
First, it saves the context of
.Fa oldtd
to its Process Control Block
.Po
PCB,
.Vt struct pcb
.Pc ,
pointed at by
.Va oldtd->td_pcb .
The function then updates important per-CPU state such as the
.Dv curthread
variable, and activates
.Fa newtd\&'s
virtual address space using its associated
.Xr pmap 9
structure.
Finally, it reads in the saved context from
.Fa newtd\&'s
PCB.
CPU instruction flow continues in the new thread context, on
.Fa newtd\&'s
kernel stack.
The return from
.Fn cpu_switch
can be understood as a completion of the function call initiated by
.Fa newtd
when it was previously switched out, at some point in the distant (relative to
CPU time) past.
.Pp
The
.Fa mtx
argument to
.Fn cpu_switch
is used to pass the mutex which will be stored as
.Fa oldtd\&'s
thread lock at the moment that
.Fa oldtd
is completely switched out.
This is an implementation detail of
.Fn sched_switch .
.Pp
.Fn cpu_throw
is similar to
.Fn cpu_switch
except that it does not save the context of the old thread.
This function is useful when the kernel does not have an old thread
context to save, such as when CPUs other than the boot CPU perform their
first task switch, or when the kernel does not care about the state of the
old thread, such as in
.Xr thread_exit 9
when the kernel terminates the current thread and switches into a new
thread,
.Fa newtd .
The
.Fa oldtd
argument is unused.
.Sh SEE ALSO
.Xr cpu_switch 9 ,
.Xr cpu_throw 9 ,
.Xr critical_exit 9 ,
.Xr issignal 9 ,
.Xr kern_yield 9 ,