I am sponsoring the following fasttrack for myself. Micro/patch binding
is requested. I believe the case qualifies for self review (since all
the interfaces are Consolidation Private) and have filed it as Closed Approved
Automatic. If there is a request, I'd be happy to convert it to a
fasttrack and set the timer to enable further discussion.
-Chris
1. Introduction
1.1. Project/Component Working Name:
ndi hidden nodes
1.2. Name of Document Author/Supplier:
Author: Chris Horne
1.3. Date of This Document:
Mon Feb 9 17:45:42 MST 2009
4.0 Technical Description
A new Nexus Driver Interface (NDI) extension that allows for
"hidden" devinfo nodes that do not appear in the /devices namespace
or in a di_init(3DEVINFO) snapshot is proposed.
This extension allows a nexus driver to control the visibility of
devinfo nodes it creates in both /devices and in di_init() devinfo
snapshots. The ability to control visibility allows a nexus to
create children as an artifact of its discovery implementation,
while preventing these transitory children from being seen by other
software.
Here are two examples of why a nexus driver may want to hide
certain devinfo nodes:
o For a nexus driver that implements a dynamic bus config [1], in
order to use a bus's existing transport mechanisms to "probe"
and obtain both configuration and identity information about
Self-Identifying Device children (SID ddi_dev_is_sid(9F)), a
fully initialized and linked "probe" devinfo node is needed.
While kernel creation and full linkage of this "probe" devinfo
node is necessary to use an existing transport, the "probe"
node is just an implementation artifact of a nexus driver's
bus_config implementation, and should not show up in the
/devices namespace or in devinfo snapshots.
A facility is needed to allow these "probe" nodes to be created
as hidden nodes. After configuration and identity information
is obtained using an initialized "probe" node, a 'real' node is
typically created - with the probe information obtained being
used to form the real node's 'compatible' property.
As an example, we want common SCSAv3 bus config code (in the
SCSA framework) to be able to DDI_CTLOPS_INITCHILD
(tran_tgt_init(9E)) a "probe" devinfo node bound to the
nulldriver [2] at an enumerated unit-address. Using this
initialized "probe" node, discovery related SCSI commands (like
INQUIRY) can be issued using an unmodified HBA transport
implementation. The information obtained is then used to to
construct the appropriate self-identifying SCSI target device
node (devinfo or pathinfo) with a 'compatible' property per
scsi(4). The "probe" node can also be used to drive
enumeration of LUNs associated with a target (using REPORTLUN).
o OBP sd(7D)/st(7D) "stub" (wildcard) nodes are an implementation
artifact that should be hidden. These nodes do not represent
devices, they have no addressing information. With a facility
to mark these nodes as hidden in a driver's
DDI_CTLOPS_INITCHILD, confusion surrounding their existence in
the Solaris device tree can be avoided.
The alternative approach of excluding node names that begin with
"." from /devices and devinfo snapshots was considered but
rejected. While a leading "." in a node name does not violate the
OpenFirmware specification (IEEE 1275), this approach would require
changing the node name via ndi_devi_set_nodename() to hide OBP
"stub" nodes.
NOTE: ndi_devi_clr_hidden is provided for completeness, I am not
aware of any immediate applicability.
4.5 Interfaces:
The following private NDI extensions allow a nexus driver to
create/mark devinfo nodes so they are excluded from /devices and
from devinfo snapshots. These are extensions of existing ndi
Private interfaces [3, 4]. The commitment level of the proposed
extensions is also Sun Private.
------------------------------------------------------------------
Interface Name Comm.Lev. Comments
------------------------------------------------------------------
DEVI_SID_HIDDEN_NODEID Cons.Private New i_ddi_alloc_node nodeid
argument used to create a node
that should be considered an
implementation artifact.
Create hidden SID node. Peer
of DEVI_SID_NODEID.
ndi_devi_set_hidden " Mark a node as hidden. Can be
used in initchild to hide nodes
that lack correct addressing
information (like stub sd OBP
nodes) or against nodes that
become implementation
artifacts. Peer of interfaces
like ndi_devi_set_nodename().
ndi_devi_clr_hidden " Mark a node as not hidden.
ndi_dev_is_hidden_node " Determine if a node is hidden.
Peer of interfaces like
ndi_dev_is_persistent_node().
DDI_HIDDEN " New devi_node_attributes bit.
Peer of DDI_PERSISTENT.
Prototypes:
void ndi_devi_set_hidden(dev_info_t *);
void ndi_devi_clr_hidden(dev_info_t *);
int ndi_dev_is_hidden_node(dev_info_t *);
4.6 Man page changes:
None.
4.7 Release Binding
Micro/patch binding is requested.
4.8 References
[1] PSARC/2002/168 Bus Config
http://sac.sfbay/PSARC/2002/168
http://www.opensolaris.org/os/community/arc/caselog/2002/168
[2] PSARC/2008/674 nulldriver
http://sac.sfbay/PSARC/2008/674
http://www.opensolaris.org/os/community/arc/caselog/2008/674
[3] PSARC/1993/687 Hot Plugging and Dynamic Configuration
http://sac.sfbay/PSARC/1993/687
http://www.opensolaris.org/os/community/arc/caselog/1993/687
[4] PSARC/1996/409 Modifications to Solaris I/O Hotplug
http://sac.sfbay/PSARC/1996/409
http://www.opensolaris.org/os/community/arc/caselog/1996/409
6. Resources and Schedule
6.4. Steering Committee requested information
6.4.1. Consolidation C-team Name:
ON
6.5. ARC review type: Automatic
6.6. ARC Exposure: open
