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fpu_kern.9: Document fpu_kern_enter API change in r329878

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While here, clean up some of the language.

Reported by:	delphij
Sponsored by:	Dell EMC Isilon
This commit is contained in:
Conrad Meyer 2018-03-07 18:31:31 +00:00
parent e9c3ceb159
commit 4e6bbdd6fe
1 changed files with 13 additions and 11 deletions
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24
share/man/man9/fpu_kern.9
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@ -23,7 +23,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd October 20, 2016
.Dd March 7, 2018
.Dt FPU_KERN 9
.Os
.Sh NAME
@ -34,7 +34,7 @@
.Fn fpu_kern_alloc_ctx "u_int flags"
.Ft void
.Fn fpu_kern_free_ctx "struct fpu_kern_ctx *ctx"
.Ft int
.Ft void
.Fn fpu_kern_enter "struct thread *td" "struct fpu_kern_ctx *ctx" "u_int flags"
.Ft int
.Fn fpu_kern_leave "struct thread *td" "struct fpu_kern_ctx *ctx"
@ -139,19 +139,15 @@ after the function returns, as well as after each context switch.
On i386 and amd64 this will be the
.Nm Device Not Available
exception (see Intel Software Developer Manual for the reference).
Currently, no errors are defined which can be returned by
.Fn fpu_kern_enter
to the caller.
.Pp
The
.Fn fpu_kern_leave
function ends the region started by
.Fn fpu_kern_enter .
The uses of FPU in the kernel after the call to
.Fn fpu_kern_leave
are erroneous until the next call to
It is erroneous to use the FPU in the kernel before
.Fn fpu_kern_enter
is performed.
or after
.Fn fpu_kern_leave .
The function takes the
.Fa td
thread argument, which currently must be
@ -161,9 +157,9 @@ and the
context pointer, previously passed to
.Fn fpu_kern_enter .
After the function returns, the context may be freed or reused
by other invocation of
by another invocation of
.Fn fpu_kern_enter .
There are no errors defined for the function, it always returns 0.
The function always returns 0.
.Pp
The
.Fn fpu_kern_thread
@ -210,3 +206,9 @@ facitily and this manual page were written by
.An Konstantin Belousov Aq Mt kib@FreeBSD.org .
The arm64 support was added by
.An Andrew Turner Aq Mt andrew@FreeBSD.org .
.Sh BUGS
.Fn fpu_kern_leave
should probably have type
.Ft void
(like
.Fn fpu_kern_enter ) .