376ccd5c9d
PR: docs/115632 Submitted by: Romain Tartiere <romain@blogreen.org> Approved by: re (bmah) MFC after: 3 days
180 lines
4.6 KiB
Groff
180 lines
4.6 KiB
Groff
.\"
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.\" Copyright (c) 2004 Pawel Jakub Dawidek <pjd@FreeBSD.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd August 13, 2007
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.Dt DECLARE_GEOM_CLASS 9
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.Os
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.Sh NAME
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.Nm DECLARE_GEOM_CLASS
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.Nd "GEOM class declaration macro"
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.Sh SYNOPSIS
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.In geom/geom.h
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.Fn DECLARE_GEOM_CLASS "class" "mod_name"
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.Sh DESCRIPTION
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The
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.Fn DECLARE_GEOM_CLASS
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macro registers a GEOM class in GEOM.
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A GEOM class itself implements one particular kind of transformation.
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Typical examples are: MBR disk partition,
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.Bx
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disklabel and RAID5 classes.
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.Fn DECLARE_GEOM_CLASS
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can be used both for compiled in and loaded as
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.Xr kld 4
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modules GEOM classes and it is the only official way for class registration.
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.Pp
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The arguments to
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.Fn DECLARE_GEOM_CLASS
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are:
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.Bl -tag -offset indent
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.It Fa class
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The
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.Vt g_class
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structure which describes a GEOM class.
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.It Fa mod_name
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A kernel module name (not a class name!).
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.El
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.Pp
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Structure
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.Vt g_class
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contains data describing the class.
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They are:
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.Bl -tag -offset indent -width indent
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.It Vt "const char *" Va name
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Class name.
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.It Vt "g_taste_t *" Va taste
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Pointer to function used for taste event handling.
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If it is
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.Pf non- Dv NULL
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it is called in three situations:
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.Pp
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.Bl -dash -compact
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.It
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On class activation, all existing providers are offered for tasting.
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.It
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When new provider is created it is offered for tasting.
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.It
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After last write access to a provider is closed it is offered for retasting
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(on first write open event
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.Dq spoil
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was sent).
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.El
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.It Vt "g_config_t *" Va config
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This field is not used anymore, its functionality was replaced by the
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.Va ctlreq
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field.
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.It Vt "g_ctl_req_t *" Va ctlreq
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Pointer to function used for handling events from userland applications.
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.It Vt "g_init_t *" Va init
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Pointer to function which is called right after class registration.
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.It Vt "g_fini_t *" Va fini
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Pointer to function which is called right before class deregistration.
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.It Vt "g_ctl_destroy_geom_t *" Va destroy_geom
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Pointer to a function which is called for every geom on class unload.
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If this field is not set, the class can not be unloaded.
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.El
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.Pp
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Only a
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.Fa name
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field is required; the rest are optional.
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.Sh RESTRICTIONS/CONDITIONS
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The fields of
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.Vt g_class
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should always be initialized using C99-style field naming
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(see the initialization of
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.Va example_class
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below).
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.Sh EXAMPLES
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Example class declaration.
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.Bd -literal -offset indent
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static struct g_geom *
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g_example_taste(struct g_class *mp, struct g_provider *pp,
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int flags __unused)
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{
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g_topology_assert();
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[...]
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}
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static void
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g_example_ctlreq(struct gctl_req *req, struct g_class *cp,
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char const *verb)
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{
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[...]
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}
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static int
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g_example_destroy_geom(struct gctl_req *req, struct g_class *cp,
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struct g_geom *gp)
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{
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g_topology_assert();
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[...]
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}
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static void
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g_example_init(struct g_class *mp)
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{
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[...]
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}
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static void
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g_example_fini(struct g_class *mp)
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{
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[...]
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}
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struct g_class example_class = {
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.name = "EXAMPLE",
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.taste = g_example_taste,
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.ctlreq = g_example_ctlreq,
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.init = g_example_init,
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.fini = g_example_fini,
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.destroy_geom = g_example_destroy_geom
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};
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DECLARE_GEOM_CLASS(example_class, g_example);
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.Ed
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.Sh SEE ALSO
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.Xr geom 4 ,
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.Xr g_attach 9 ,
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.Xr g_bio 9 ,
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.Xr g_consumer 9 ,
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.Xr g_data 9 ,
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.Xr g_event 9 ,
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.Xr g_geom 9 ,
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.Xr g_provider 9 ,
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.Xr g_provider_by_name 9 ,
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.Xr g_wither_geom 9
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.Sh AUTHORS
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.An -nosplit
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This manual page was written by
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.An Pawel Jakub Dawidek Aq pjd@FreeBSD.org .
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