gld(7D)
NAME
gld - Generic LAN Driver
SYNOPSIS
#include <sys/stropts.h>
#include <sys/stream.h>
#include <sys/dlpi.h>
#include <sys/gld.h>
INTERFACE LEVEL
Solaris architecture specific (Solaris DDI).
DESCRIPTION
GLD is a multi-threaded, clonable, loadable kernel module
providing support for Solaris local area network (LAN) dev-
ice drivers. LAN drivers in Solaris are STREAMS-based
drivers that use the Data Link Provider Interface (DLPI) to
communicate with network protocol stacks. These protocol
stacks use the network drivers to send and receive packets
on a local area network. A network device driver must imple-
ment and adhere to the requirements imposed by the DDI/DKI
specification, STREAMS specification, DLPI specification,
and programmatic interface of the device itself.
GLD implements most STREAMS and DLPI functionality required
of a Solaris LAN driver. Several Solaris network drivers are
implemented using GLD.
A Solaris network driver implemented using GLD comprises two
distinct parts: a generic component that deals with STREAMS
and DLPI interfaces, and a device-specific component that
deals with the particular hardware device. The device-
specific module indicates its dependency on the GLD module
and registers itself with GLD from within the driver's
attach(9E) function. Once it is successfully loaded, the
driver is DLPI-compliant. The device-specific part of the
driver calls gld(9F) functions when it receives data or
needs some service from GLD. GLD makes calls into the
gld(9E) entry points of the device-specific driver through
pointers provided to GLD by the device-specific driver when
it registered itself with GLD. The gld_mac_info(9S) struc-
ture is the main data interface between GLD and the device-
specific driver.
The GLD facility currently supports devices of type
DL_ETHER, DL_TPR, and DL_FDDI. GLD drivers are expected to
process fully-formed MAC-layer packets and should not per-
form logical link control (LLC) handling.
In some cases, it may be necessary or desirable to implement
a full DLPI-compliant driver without using the GLD facility.
This is true for devices that are not IEEE 802-style LAN
devices, or where a device type or DLPI service not sup-
ported by GLD is required.
Device Naming Constraints
The name of the device-specific driver module must adhere to
the naming constraints outlined in the NOTES section of
dlpi(7P).
Type DL_ETHER: Ethernet V2 and ISO 8802-3 (IEEE 802.3)
For devices designated type DL_ETHER, GLD provides support
for both Ethernet V2 and ISO 8802-3 (IEEE 802.3) packet pro-
cessing. Ethernet V2 enables a data link service user to
access and use any of a variety of conforming data link ser-
vice providers without special knowledge of the provider's
protocol. A service access point (SAP) is the point through
which the user communicates with the service provider.
Streams bound to SAP values in the range [0-255] are treated
as equivalent and denote that the user wishes to use 802.3
mode. If the value of the SAP field of the DL_BIND_REQ is
within this range, GLD computes the length, not including
the 14-byte MAC header, of each subsequent DL_UNITDATA_REQ
message on that stream and transmits 802.3 frames having
that length in the MAC frame header type field. Such lengths
will never exceed 1500.
All frames received from the media that have a type field in
the range [0-1500] are assumed to be 802.3 frames and are
routed up all open streams that are in 802.3 mode, (those
streams bound to a SAP value in the [0-255] range). If more
than one stream is in 802.3 mode, the incoming frame will be
duplicated and routed up each such stream.
Streams bound to SAP values > 1500 receive incoming packets
whose Ethernet MAC header type value exactly matches the
value of the SAP to which the stream is bound.
Types DL_TPR and DL_FDDI: SNAP Processing
For media types DL_TPR and DL_FDDI, GLD implements minimal
SNAP (Sub-Net Access Protocol) processing for any stream
bound to a SAP value greater than 255. SAP values in the
range [0-255] are LLC SAP values and are carried naturally
by the media packet format. SAP values greater than 255
require a SNAP header, under the LLC header, to carry the
16-bit Ethernet V2-style SAP value.
SNAP headers are carried under LLC headers with destination
SAP 0xAA. For outgoing packets with SAP values greater than
255, GLD creates an LLC+ SNAP header that always looks like:
``AA AA 03 00 00 00 XX XX''
where ``XX XX'' represents the 16-bit SAP, corresponding to
the Ethernet V2 style ``type.'' This is the only class of
SNAP header supported - non-zero OUI fields, and LLC control
fields other than 03 are considered to be LLC packets with
SAP 0xAA. Clients wishing to use SNAP formats other than
this one must use LLC and bind to SAP 0xAA.
Incoming packets are examined to ascertain whether they fall
into the format specified above. Packets that do will be
matched to streams bound to the packet's 16-bit SNAP type,
as well as being considered to match the LLC SNAP SAP 0xAA.
Packets received for any LLC SAP are passed up all streams
that are bound to an LLC SAP, as described for media type
DL_ETHER above.
Type DL_TPR: Source Routing
For type DL_TPR devices, GLD implements minimal support for
source routing. Source routing enables a station that is
sending a packet across a bridged medium to specify (in the
packet MAC header) routing information that determines the
route that the packet will take through the network.
Functionally, the source routing support provided by GLD
learns routes, solicits and responds to requests for infor-
mation about possible multiple routes and selects among the
multiple routes that are available. It adds Routing Informa-
tion Fields to the MAC headers of outgoing packets and
recognizes such fields in incoming packets.
GLD's source routing support does not implement the full
Route Determination Entity (RDE) specified in ISO 8802-2
(IEEE 802.2) Section 9. However, it is designed to intero-
perate with any such implementations that may exist in the
same (or a bridged) network.
Style 1 and 2 Providers
GLD implements both Style 1 and Style 2 providers. A physi-
cal point of attachment (PPA) is the point at which a system
attaches itself to a physical communication medium. All com-
munication on that physical medium funnels through the PPA.
The Style 1 provider attaches the stream to a particular PPA
based on the major/minor device that has been opened. The
Style 2 provider requires the DLS user to explicitly iden-
tify the desired PPA using DL_ATTACH_REQ. In this case,
open(9E) creates a stream between the user and GLD and
DL_ATTACH_REQ subsequently associates a particular PPA with
that stream. Style 2 is denoted by a minor number of zero.
If a device node whose minor number is not zero is opened,
Style 1 is indicated and the associated PPA is the minor
number minus 1. In both Style 1 and Style 2 opens, the dev-
ice is cloned.
Implemented DLPI Primitives
GLD implements the following DLPI primitives:
The DL_INFO_REQ primitive requests information about the
DLPI stream. The message consists of one M_PROTO message
block. GLD returns device-dependent values in the
DL_INFO_ACK response to this request, based on information
the GLD-based driver specified in the gld_mac_info(9S)
structure passed to gld_register(). However GLD returns the
following values on behalf of all GLD-based drivers:
o The version is DL_VERSION_2.
o The service mode is DL_CLDLS - GLD implements
connectionless-mode service.
o The provider style is DL_STYLE1 or DL_STYLE2, depend-
ing on how the stream was opened.
o No optional Quality Of Service (QOS) support is
present and the QOS fields are zero.
The DL_ATTACH_REQ primitive is called to associate a PPA
with a stream. This request is needed for Style 2 DLS pro-
viders to identify the physical medium over which the com-
munication will transpire. Upon completion, the state
changes from DL_UNATTACHED to DL_UNBOUND. The message con-
sists of one M_PROTO message block. This request may not be
issued when using the driver in Style 1 mode; streams opened
using Style 1 are already attached to a PPA by the time the
open completes.
The DL_DETACH_REQ primitive requests to detach the PPA from
the stream. This is only allowed if the stream was opened
using Style 2.
The DL_BIND_REQ and DL_UNBIND_REQ primitives bind and unbind
a DLSAP to the stream. The PPA associated with each stream
will have been initialized upon completion of the processing
of the DL_BIND_REQ. Multiple streams may be bound to the
same SAP; each such stream receives a copy of any packets
received for that SAP.
The DL_ENABMULTI_REQ and DL_DISABMULTI_REQ primitives enable
and disable reception of individual multicast group
addresses. A set of multicast addresses may be iteratively
created and modified on a per-stream basis using these prim-
itives. The stream must be attached to a PPA for these
primitives to be accepted.
The DL_PROMISCON_REQ and DL_PROMISCOFF_REQ primitives enable
and disable promiscuous mode on a per-stream basis, either
at a physical level or at the SAP level. The DL Provider
will route all received messages on the media to the DLS
user until either a DL_DETACH_REQ or a DL_PROMISCOFF_REQ is
received or the stream is closed. Physical level promiscuous
mode may be specified for all packets on the medium or for
multicast packets only. The stream must be attached to a PPA
for these primitives to be accepted.
The DL_UNITDATA_REQ primitive is used to send data in a con-
nectionless transfer. Because this is an unacknowledged ser-
vice, there is no guarantee of delivery. The message con-
sists of one M_PROTO message block followed by one or more
M_DATA blocks containing at least one byte of data.
The DL_UNITDATA_IND type is used when a packet is received
and is to be passed upstream. The packet is put into an
M_PROTO message with the primitive set to DL_UNITDATA_IND.
The DL_PHYS_ADDR_REQ primitive returns the MAC address
currently associated with the PPA attached to the stream, in
the DL_PHYS_ADDR_ACK primitive. When using style 2, this
primitive is only valid following a successful
DL_ATTACH_REQ.
The DL_SET_PHYS_ADDR_REQ primitive changes the MAC address
currently associated with the PPA attached to the stream.
This primitive affects all other current and future streams
attached to this device. Once changed, all streams currently
or subsequently opened and attached to this device will
obtain this new physical address. The new physical address
will remain in effect until this primitive is used to change
the physical address again or the driver is reloaded.
The DL_GET_STATISTICS_REQ primitive requests a
DL_GET_STATISTICS_ACK response containing statistics infor-
mation associated with the PPA attached to the stream. Style
2 streams must be attached to a particular PPA using
DL_ATTACH_REQ before this primitive will be successful.
Implemented ioctl Functions
GLD implements the ioctl ioc_cmd function described below.
If GLD receives an ioctl command that it does not recognize,
it passes it to the device-specific driver's gldm_ioctl()
routine as described in gld(9E).
The DLIOCRAW ioctl function is used by some DLPI applica-
tions, most notably the snoop(1M) command. The DLIOCRAW com-
mand puts the stream into a raw mode, which, upon receive,
causes the the full MAC-level packet to be sent upstream in
an M_DATA message instead of it being transformed into the
DL_UNITDATA_IND form normally used for reporting incoming
packets. Packet SAP filtering is still performed on streams
that are in raw mode; if a stream user wants to receive all
incoming packets it must also select the appropriate promis-
cuous modes. After successfully selecting raw mode, the
application is also allowed to send fully formatted packets
to the driver as M_DATA messages for transmission. DLIOCRAW
takes no arguments. Once enabled, the stream remains in this
mode until closed.
Requirements on GLD Drivers
GLD-based drivers must include the header file <sys/gld.h>.
GLD-based drivers must also include the following declara-
tion:
char _depends_on[] = "misc/gld";
GLD implements the open(9E) and close(9E) functions and the
required STREAMS put(9E) and srv(9E) functions on behalf of
the device-specific driver. GLD also implements the
getinfo(9E) function for the driver.
The mi_idname element of the module_info(9S) structure is a
string specifying the name of the driver. This must exactly
match the name of the driver module as it exists in the file
system.
The read-side qinit(9S) structure should specify the follow-
ing elements as shown below:
qi_putp
NULL
qi_srvp
gld_rsrv
qi_qopen
gld_open
qi_qclose
gld_close
The write-side qinit(9S) structure should specify the fol-
lowing elements as shown below:
qi_putp
gld_wput
qi_srvp
gld_wsrv
qi_qopen
NULL
qi_qclose
NULL
The devo_getinfo element of the dev_ops(9S) structure should
specify gld_getinfo as the getinfo(9E) routine.
The driver's attach(9E) function does all the work of asso-
ciating the hardware-specific device driver with the GLD
facility and preparing the device and driver for use.
The attach(9E) function allocates a gld_mac_info(9S)
(``macinfo'') structure using gld_mac_alloc(). The driver
usually needs to save more information per device than is
defined in the macinfo structure; it should allocate the
additional required data structure and save a pointer to it
in the gldm_private member of the gld_mac_info(9S) struc-
ture.
The attach(9E) routine must initialize the macinfo structure
as described in gld_mac_info(9S) and then call
gld_register() to link the driver with the GLD module. The
driver should map registers if necessary and be fully ini-
tialized and prepared to accept interrupts before calling
gld_register(). The attach(9E) function should add inter-
rupts but not enable the device to generate them. The driver
should reset the hardware before calling gld_register() to
ensure it is quiescent; the device must not be started or
put into a state where it may generate an interrupt before
gld_register() is called. That will be done later when GLD
calls the driver's gldm_start() entry point described in
gld(9E). Once gld_register() succeeds, the gld(9E) entry
points may be called by GLD at any time.
The attach(9E) routine should return DDI_SUCCESS if
gld_register() succeeds. If gld_register() fails, it returns
DDI_FAILURE and the attach(9E) routine should deallocate any
resources it allocated before calling gld_register() and
then also return DDI_FAILURE. Under no circumstances should
a failed macinfo structure be reused; it should be deallo-
cated using gld_mac_free().
The detach(9E) function should attempt to unregister the
driver from GLD. This is done by calling gld_unregister()
described in gld(9F). The detach(9E) routine can get a
pointer to the needed gld_mac_info(9S) structure from the
device's private data using ddi_get_driver_private(9F).
gld_unregister() checks certain conditions that could
require that the driver not be detached. If the checks fail,
gld_unregister() returns DDI_FAILURE, in which case the
driver's detach(9E) routine must leave the device opera-
tional and return DDI_FAILURE. If the checks succeed,
gld_unregister() ensures that the device interrupts are
stopped, calling the driver's gldm_stop() routine if neces-
sary, unlinks the driver from the GLD framework, and returns
DDI_SUCCESS. In this case, the detach(9E) routine should
remove interrupts, deallocate any data structures allocated
in the attach(9E) routine, using gld_mac_free() to deallo-
cate the macinfo structure, and return DDI_SUCCESS. It is
important to remove the interrupt before calling
gld_mac_free().
Network Statistics
Solaris network drivers must implement statistics variables.
GLD itself tallies some network statistics, but other
statistics must be counted by each GLD-based driver. GLD
provides support for GLD-based drivers to report a standard
set of network driver statistics. Statistics are reported by
GLD using the kstat(7D) and kstat(9S) mechanism. The
DL_GET_STATISTICS_REQ DLPI command may also be used to
retrieve the current statistics counters. All statistics are
maintained as unsigned, and all are 32 bits unless otherwise
noted.
GLD maintains and reports the following statistics.
rbytes64
Total bytes successfully received on the interface (64
bits).
rbytes
Total bytes successfully received on the interface.
obytes64
Total bytes requested to be transmitted on the inter-
face (64 bits).
obytes
Total bytes requested to be transmitted on the inter-
face.
ipackets64
Total packets successfully received on the interface
(64 bits).
ipackets
Total packets successfully received on the interface.
opackets64
Total packets requested to be transmitted on the
interface (64 bits).
opackets
Total packets requested to be transmitted on the
interface.
multircv
Multicast packets successfully received, including
group and functional addresses (long).
multixmt
Multicast packets requested to be transmitted, includ-
ing group and functional addresses (long).
brdcstrcv
Broadcast packets successfully received (long).
brdcstxmt
Broadcast packets requested to be transmitted (long).
unknowns
Valid received packets not accepted by any stream
(long).
noxmtbuf
Packets discarded on output because transmit buffer
was busy, or no buffer could be allocated for transmit
(long).
blocked
Times a received packet could not be put up a stream
because the queue was flow controlled (long).
xmtretry
Times transmit was retried after having been delayed
due to lack of resources (long).
promisc
Current ``promiscuous'' state of the interface
(string).
The device dependent driver counts the following statistics,
keeping track of them in a private per-instance structure.
When GLD is asked to report statistics, it calls the
driver's gldm_get_stats() entry point, as described in
gld(9E), to update the device-specific statistics in the
gld_stats(9S) structure. GLD then reports the updated
statistics using the named statistics variables below.
ifspeed
Current estimated bandwidth of the interface in bits
per second (64 bits).
media Current media type in use by the device (string).
intr Times interrupt handler was called and claimed the
interrupt (long).
norcvbuf
Times a valid incoming packet was known to have been
discarded because no buffer could be allocated for
receive (long).
ierrors
Total packets received that couldn't be processed
because they contained errors (long).
oerrors
Total packets that weren't successfully transmitted
because of errors (long).
missed
Packets known to have been dropped by the hardware on
receive (long).
uflo Times FIFO underflowed on transmit (long).
oflo Times receiver overflowed during receive (long).
The following group of statistics applies to networks of
type DL_ETHER; these are maintained by device-specific
drivers of that type, as above.
align_errors
Packets received with framing errors (not an integral
number of octets) (long).
fcs_errors
Packets received with CRC errors (long).
duplex
Current duplex mode of the interface (string).
carrier_errors
Times carrier was lost or never detected on a
transmission attempt (long).
collisions
Ethernet collisions during transmit (long).
ex_collisions
Frames where excess collisions occurred on transmit,
causing transmit failure (long).
tx_late_collisions
Times a transmit collision occurred late (after 512
bit times) (long).
defer_xmts
Packets without collisions where first transmit
attempt was delayed because the medium was busy
(long).
first_collisions
Packets successfully transmitted with exactly one col-
lision.
multi_collisions
Packets successfully transmitted with multiple colli-
sions.
sqe_errors
Times SQE test error was reported.
macxmt_errors
Packets encountering transmit MAC failures, except
carrier and collision failures.
macrcv_errors
Packets received with MAC errors, except align, fcs,
and toolong errors.
toolong_errors
Packets received larger than the maximum permitted
length.
runt_errors
Packets received smaller than the minimum permitted
length (long).
The following group of statistics applies to networks of
type DL_TPR; these are maintained by device-specific drivers
of that type, as above.
line_errors
Packets received with non-data bits or FCS errors.
burst_errors
Times an absence of transitions for five half-bit
timers was detected.
signal_losses
Times loss of signal condition on the ring was
detected.
ace_errors
Times an AMP or SMP frame in which A is equal to C is
equal to 0, was followed by another such SMP frame
without an intervening AMP frame.
internal_errors
Times the station recognized an internal error.
lost_frame_errors
Times the TRR timer expired during transmit.
frame_copied_errors
Times a frame addressed to this station was received
with the FS field A bit set to 1.
token_errors
Times the station acting as the active monitor recog-
nized an error condition that needed a token transmit-
ted.
freq_errors
Times the frequency of the incoming signal differed
from the expected frequency.
The following group of statistics applies to networks of
type DL_FDDI; these are maintained by device-specific
drivers of that type, as above.
mac_errors
Frames detected in error by this MAC that had not been
detected in error by another MAC.
mac_lost_errors
Frames received with format errors such that the frame
was stripped.
mac_tokens
Number of tokens received (total of non-restricted and
restricted).
mac_tvx_expired
Number of times that TVX has expired.
mac_late
Number of TRT expirations since this MAC was reset or
a token was received.
mac_ring_ops
Number of times the ring has entered the
``Ring_Operational'' state from the ``Ring Not Opera-
tional'' state.
FILES
/kernel/misc/gld
loadable kernel module
SEE ALSO
kstat(7D), dlpi(7P), attach(9E), gld(9E), open(9E), gld(9F),
gld_mac_info(9S), gld_stats(9S), kstat(9S)
Writing Device Drivers
WARNINGS
Contrary to the DLPI specification, GLD returns the device's
correct address length and broadcast address in DL_INFO_ACK
even before the stream has been attached to a PPA.
Promiscuous mode may only be entered by streams that are
attached to a PPA.
The physical address of a PPA may be changed by the
superuser while other streams are bound to the same PPA.
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