sk98lin(4)

sk98lin(4) — Kernel Interfaces Manual 🌈

okay so bestie, welcome to the sk98lin(4) page 💖 this is the Kernel Interfaces Manual, and we're about to get into the Marvell/SysKonnect Gigabit Ethernet driver. it's giving vintage, but we're gonna make it make sense. no cap.

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✨ NAME ✨

• sk98lin — Marvell/SysKonnect Gigabit Ethernet driver v6.21 🎀

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🦋 SYNOPSIS 🦋

insmod sk98lin.o [Speed_A=i,j,...]  [Speed_B=i,j,...]
[AutoNeg_A=i,j,...]  [AutoNeg_B=i,j,...]  [DupCap_A=i,j,...]
[DupCap_B=i,j,...]  [FlowCtrl_A=i,j,...]  [FlowCtrl_B=i,j,...]
[Role_A=i,j,...]  [Role_B=i,j,...]  [ConType=i,j,...]
[Moderation=i,j,...]  [IntsPerSec=i,j,...]  [PrefPort=i,j,...]
[RlmtMode=i,j,...]

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💅 DESCRIPTION 💅

⚠️ Note: This obsolete driver was removed in Linux 2.6.26. 💀

so sk98lin is the Gigabit Ethernet driver for Marvell and SysKonnect network adapter cards 💖 it supports the SysKonnect SK-98xx/SK-95xx compliant Gigabit Ethernet Adapter and any Yukon compliant chipset. periodt.

when loading the driver using insmod, parameters for the network adapter cards might be stated as a sequence of comma separated commands. if for instance two network adapters are installed and AutoNegotiation on Port A of the first adapter should be ON, but on the Port A of the second adapter switched OFF, one must enter:

insmod sk98lin.o AutoNeg_A=On,Off

after sk98lin is bound to one or more adapter cards and the /proc filesystem is mounted on your system, a dedicated statistics file will be created in the folder /proc/net/sk98lin for all ports of the installed network adapter cards. those files are named eth[x], where x is the number of the interface that has been assigned to a dedicated port by the system. iykyk.

if loading is finished, any desired IP address can be assigned to the respective eth[x] interface using the ifconfig(8) command. this causes the adapter to connect to the Ethernet and to display a status message on the console saying "ethx: network connection up using port y" followed by the configured or detected connection parameters. slay.

the sk98lin also supports large frames (also called jumbo frames). using jumbo frames can improve throughput tremendously when transferring large amounts of data. to enable large frames, the MTU (maximum transfer unit) size for an interface is to be set to a high value. the default MTU size is 1500 and can be changed up to 9000 (bytes). setting the MTU size can be done when assigning the IP address to the interface or later by using the ifconfig(8) command with the mtu parameter. if for instance eth0 needs an IP address and a large frame MTU size, the following two commands might be used:

ifconfig eth0 10.1.1.1
ifconfig eth0 mtu 9000

those two commands might even be combined into one:

ifconfig eth0 10.1.1.1 mtu 9000

note that large frames can be used only if permitted by your network infrastructure. this means, that any switch being used in your Ethernet must also support large frames. quite some switches support large frames, but need to be configured to do so. most of the times, their default setting is to support only standard frames with an MTU size of 1500 (bytes). in addition to the switches inside the network, all network adapters that are to be used must also be enabled regarding jumbo frames. if an adapter is not set to receive large frames, it will simply drop them. 💀

switching back to the standard Ethernet frame size can be done by using the ifconfig(8) command again:

ifconfig eth0 mtu 1500

the Marvell/SysKonnect Gigabit Ethernet driver for Linux is able to support VLAN and Link Aggregation according to IEEE standards 802.1, 802.1q, and 802.3ad. those features are available only after installation of open source modules which can be found on the Internet:

• VLAN: http://www.candelatech.com/~greear/vlan.html
• Link Aggregation: http://www.st.rim.or.jp/~yumo

note that Marvell/SysKonnect does not offer any support for these open source modules and does not take the responsibility for any kind of failures or problems arising when using these modules. 🙈

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🎀 Parameters 🎀

• Speed_A=i,j,... — this parameter is used to set the speed capabilities of port A of an adapter card. it is valid only for Yukon copper adapters. possible values are: 10, 100, 1000, or Auto; Auto is the default. usually, the speed is negotiated between the two ports during link establishment. if this fails, a port can be forced to a specific setting with this parameter. 💖
• Speed_B=i,j,... — this parameter is used to set the speed capabilities of port B of an adapter card. it is valid only for Yukon copper adapters. possible values are: 10, 100, 1000, or Auto; Auto is the default. usually, the speed is negotiated between the two ports during link establishment. if this fails, a port can be forced to a specific setting with this parameter. 💖
• AutoNeg_A=i,j,... — enables or disables the use of autonegotiation of port A of an adapter card. possible values are: On, Off, or Sense; On is the default. the Sense mode automatically detects whether the link partner supports auto-negotiation or not. ✨
• AutoNeg_B=i,j,... — enables or disables the use of autonegotiation of port B of an adapter card. possible values are: On, Off, or Sense; On is the default. the Sense mode automatically detects whether the link partner supports auto-negotiation or not. ✨
• DupCap_A=i,j,... — this parameter indicates the duplex mode to be used for port A of an adapter card. possible values are: Half, Full, or Both; Both is the default. this parameter is relevant only if AutoNeg_A of port A is not set to Sense. if AutoNeg_A is set to On, all three values of DupCap_A (Half, Full, or Both) might be stated. if AutoNeg_A is set to Off, only DupCap_A values Full and Half are allowed. this DupCap_A parameter is useful if your link partner does not support all possible duplex combinations. 🦋
• DupCap_B=i,j,... — this parameter indicates the duplex mode to be used for port B of an adapter card. possible values are: Half, Full, or Both; Both is the default. this parameter is relevant only if AutoNeg_B of port B is not set to Sense. if AutoNeg_B is set to On, all three values of DupCap_B (Half, Full, or Both) might be stated. if AutoNeg_B is set to Off, only DupCap_B values Full and Half are allowed. this DupCap_B parameter is useful if your link partner does not support all possible duplex combinations. 🦋
• FlowCtrl_A=i,j,... — this parameter can be used to set the flow control capabilities the port reports during auto-negotiation. possible values are: Sym, SymOrRem, LocSend, or None; SymOrRem is the default. the different modes have the following meaning:
  • Sym = Symmetric — both link partners are allowed to send PAUSE frames.
  • SymOrRem = SymmetricOrRemote — both or only remote partner are allowed to send PAUSE frames.
  • LocSend = LocalSend — only local link partner is allowed to send PAUSE frames.
  • None = None — no link partner is allowed to send PAUSE frames. note that this parameter is ignored if AutoNeg_A is set to Off. 💅
• FlowCtrl_B=i,j,... — this parameter can be used to set the flow control capabilities the port reports during auto-negotiation. possible values are: Sym, SymOrRem, LocSend, or None; SymOrRem is the default. the different modes have the following meaning:
  • Sym = Symmetric — both link partners are allowed to send PAUSE frames.
  • SymOrRem = SymmetricOrRemote — both or only remote partner are allowed to send PAUSE frames.
  • LocSend = LocalSend — only local link partner is allowed to send PAUSE frames.
  • None = None — no link partner is allowed to send PAUSE frames. note that this parameter is ignored if AutoNeg_B is set to Off. 💅
• Role_A=i,j,... — this parameter is valid only for 1000Base-T adapter cards. for two 1000Base-T ports to communicate, one must take the role of the master (providing timing information), while the other must be the slave. possible values are: Auto, Master, or Slave; Auto is the default. usually, the role of a port is negotiated between two ports during link establishment, but if that fails the port A of an adapter card can be forced to a specific setting with this parameter. 👑
• Role_B=i,j,... — this parameter is valid only for 1000Base-T adapter cards. for two 1000Base-T ports to communicate, one must take the role of the master (providing timing information), while the other must be the slave. possible values are: Auto, Master, or Slave; Auto is the default. usually, the role of a port is negotiated between two ports during link establishment, but if that fails the port B of an adapter card can be forced to a specific setting with this parameter. 👑
• ConType=i,j,... — this parameter is a combination of all five per-port parameters within one single parameter. this simplifies the configuration of both ports of an adapter card. the different values of this variable reflect the most meaningful combinations of port parameters. possible values and their corresponding combination of per-port parameters:

ConType   DupCap   AutoNeg   FlowCtrl   Role   Speed
Auto      Both     On        SymOrRem   Auto   Auto
100FD     Full     Off       None       Auto   100
100HD     Half     Off       None       Auto   100
10FD      Full     Off       None       Auto   10
10HD      Half     Off       None       Auto   10

stating any other port parameter together with this ConType parameter will result in a merged configuration of those settings. this is due to the fact, that the per-port parameters (e.g., Speed_A) have a higher priority than the combined variable ConType. 🔥

• Moderation=i,j,... — interrupt moderation is employed to limit the maximum number of interrupts the driver has to serve. that is, one or more interrupts (which indicate any transmit or receive packet to be processed) are queued until the driver processes them. when queued interrupts are to be served, is determined by the IntsPerSec parameter, which is explained later below. possible moderation modes are: None, Static, or Dynamic; None is the default. the different modes have the following meaning:
• None — zero moderation, bestie. Every single transmit or receive interrupt gets served immediately, the literal second it appears on the interrupt line of the adapter card. ✨
• Static — moderation is on, and it stays on. All transmit and receive interrupts get queued until a complete moderation interval ends. Once that interval ends, everything queued gets processed in one big bunch, no delay at all. 💥 The word Static is here to remind you that moderation is always enabled, no matter how much network load is currently passing through a particular interface. On top of that, the duration of the moderation interval has a fixed length that never changes while the driver is operational. 🧊
• Dynamic — moderation might be applied on the adapter card, depending on the load of the system. If the driver detects the system load is too high, it tries to shield the system against too much network load by enabling interrupt moderation. And then — if at a later time the CPU utilization decreases again (or the network load is just negligible) — the interrupt moderation disables itself automatically. self-regulating queen behavior 🦋

Interrupt moderation should be used when the driver has to handle one or more interfaces with a high network load, which — as a consequence — also leads to high CPU utilization. When moderation is applied in those high network load situations, CPU load might be reduced by 20–30% on slow computers. 👑

Heads up though: the drawback of using interrupt moderation is an increase of the round-trip-time (RTT), because of the queuing and serving of interrupts at dedicated moderation times. Trade-offs are real, bestie. 😭

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IntsPerSec=i,j,...

This parameter determines the length of any interrupt moderation interval. Say static interrupt moderation is what you're using — then an IntsPerSec parameter value of 2000 will lead to an interrupt moderation interval of 500 microseconds. ⏱️ Possible values for this parameter live in the range of 30...40000 (interrupts per second). The default value is 2000.

This parameter is used only if either static or dynamic interrupt moderation is enabled on a network adapter card. If no moderation is applied, this parameter is ignored. 🚫

Note that the duration of the moderation interval is to be chosen with care, fr fr. At first glance, picking a very long duration (e.g., only 100 interrupts per second) seems meaningful, but the increase of packet-processing delay is tremendous. On the other hand, picking a very short moderation time might compensate the use of any moderation being applied. 💀

PrefPort=i,j,...

This parameter forces the preferred port to A or B (relevant on dual-port network adapters). The preferred port is the one that gets used if both ports A and B are detected as fully functional. Possible values are: A or B; and A is the default. 🅰️

RlmtMode=i,j,...

RLMT monitors the status of the port. If the link of the active port fails, RLMT switches immediately to the standby link, and the virtual link is maintained as long as at least one "physical" link is up. 🔗 This parameter states how RLMT should monitor both ports. Possible values are: CheckLinkState, CheckLocalPort, CheckSeg, or DualNet — and CheckLinkState is the default. The different modes mean the following:

• CheckLinkState — check link state only. RLMT uses the link state reported by the adapter hardware for each individual port to figure out whether a port can be used for all network traffic or not. ✅
• CheckLocalPort — in this mode, RLMT monitors the network path between the two ports of an adapter by regularly exchanging packets between them. It requires a network configuration in which the two ports are able to "see" each other (i.e., there must not be any router between the ports). 👀
• CheckSeg — check local port and segmentation. This mode supports the same functions as the CheckLocalPort mode and additionally checks network segmentation between the ports. Because of that extra job, it's to be used only if Gigabit Ethernet switches are installed on the network that have been configured to use the Spanning Tree protocol. 🌳
• DualNet — in this mode, ports A and B are used as separate devices. If you have a dual port adapter, port A will be configured as eth[x] and port B as eth[x+1]. Both ports can be used independently with distinct IP addresses. The preferred port setting is not used, and RLMT is turned off. 🚪🚪

Note that RLMT modes CheckLocalPort and CheckLinkState are designed to operate in configurations where a network path between the ports on one adapter exists. Moreover, they are not designed to work where adapters are connected back-to-back. 🙈

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📁 FILES 📁

• /proc/net/sk98lin/eth[x] — the statistics file of a particular interface of an adapter card. It's got generic information about the adapter card plus a detailed summary of all transmit and receive counters. 📊
• /usr/src/linux/Documentation/networking/sk98lin.txt — this is the README file of the sk98lin driver. It contains a detailed installation HOWTO and describes all parameters of the driver. It also denotes common problems and provides the solution to them. 🩹

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🐛 BUGS 🐛

Report any bugs to linux@syskonnect.de. Tell them everything, no gatekeeping. 💌

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👀 SEE ALSO 👀

ifconfig(8), insmod(8), modprobe(8) — go read those next, bestie, they're the supporting cast. 🌸

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and that's the whole page, periodt 💅 This lil masterpiece is from the Linux man-pages collection, version 6.20, and it's dated 2026-02-08 — so yeah, it's giving freshly-shipped, iconic, and most importantly: you now know it. 🫶✨🎀