1 # Configuring the DragonFly Kernel
3 ***Updated and restructured by Jim Mock. Originally contributed by Jake Hamby.***
9 The kernel is the core of the DragonFly operating system. It is responsible for managing memory, enforcing security controls, networking, disk access, and much more. While more and more of DragonFly becomes dynamically configurable it is still occasionally necessary to reconfigure and recompile your kernel.
11 After reading this chapter, you will know:
13 * Why you might need to build a custom kernel.
14 * How to write a kernel configuration file, or alter an existing configuration file.
15 * How to use the kernel configuration file to create and build a new kernel.
16 * How to install the new kernel.
17 * How to troubleshoot if things go wrong.
19 ## Why Build a Custom Kernel?
21 Traditionally, DragonFly has had what is called a ***monolithic*** kernel. This means that the kernel was one large program, supported a fixed list of devices, and if you wanted to change the kernel's behavior then you had to compile a new kernel, and then reboot your computer with the new kernel.
23 Today, DragonFly is rapidly moving to a model where much of the kernel's functionality is contained in modules which can be dynamically loaded and unloaded from the kernel as necessary. This allows the kernel to adapt to new hardware suddenly becoming available (such as PCMCIA cards in a laptop), or for new functionality to be brought into the kernel that was not necessary when the kernel was originally compiled. This is known as a modular kernel. Colloquially these are called KLDs.
25 Despite this, it is still necessary to carry out some static kernel configuration. In some cases this is because the functionality is so tied to the kernel that it can not be made dynamically loadable. In others it may simply be because no one has yet taken the time to write a dynamic loadable kernel module for that functionality yet.
27 Building a custom kernel is one of the most important rites of passage nearly every UNIX® user must endure. This process, while time consuming, will provide many benefits to your DragonFly system. Unlike the `GENERIC` kernel, which must support a wide range of hardware, a custom kernel only contains support for ***your*** PC's hardware. This has a number of benefits, such as:
29 * Faster boot time. Since the kernel will only probe the hardware you have on your system, the time it takes your system to boot will decrease dramatically.
31 * Less memory usage. A custom kernel often uses less memory than the `GENERIC` kernel, which is important because the kernel must always be present in real memory. For this reason, a custom kernel is especially useful on a system with a small amount of RAM.
33 * Additional hardware support. A custom kernel allows you to add in support for devices such as sound cards, which are not present in the `GENERIC` kernel.
35 ## Building and Installing a Custom Kernel
37 First, let us take a quick tour of the kernel build directory. All directories mentioned will be relative to the main `/usr/src/sys` directory, which is also accessible through `/sys`. There are a number of subdirectories here representing different parts of the kernel, but the most important, for our purposes, is `config`, where you will edit your custom kernel configuration, and `compile`, which is the staging area where your kernel will be built. Notice the logical organization of the directory structure, with each supported device, file system, and option in its own subdirectory.
39 ### Installing the Source
41 If there is ***no*** `/usr/src/sys` directory on your system, then the kernel source has not been installed. One method to do this is via git. An alternative is to install the kernel source tree from the archive distributed on the DragonFly CD named `src-sys.tar.bz2`. This is especially useful when you do not have ready access to the internet. Use the Makefile in `/usr` to fetch the source or to unpack the archive. When installing kernel source only, use the alternate build procedure below.
43 The preferred way of installing the sources is:
48 This will download the whole source tree via git into /usr/src. This method also allows for easy updating of the source tree by using:
52 ### Your Custom Config File
54 Next, move to the `config` directory and copy the `GENERIC` configuration file to the name you want to give your kernel. For example:
56 # cd /usr/src/sys/config
59 Traditionally, this name is in all capital letters and, if you are maintaining multiple DragonFly machines with different hardware, it is a good idea to name it after your machine's hostname. We will call it `MYKERNEL` for the purpose of this example.
61 **Tip:** Storing your kernel config file directly under `/usr/src` can be a bad idea. If you are experiencing problems it can be tempting to just delete `/usr/src` and start again. Five seconds after you do that you realize that you have deleted your custom kernel config file. Do not edit `GENERIC` directly, as it may get overwritten the next time you [update your source tree](updating.html#UPDATING-SETUP), and your kernel modifications will be lost. You might want to keep your kernel config file elsewhere, and then create a symbolic link to the file in the `config` directory.
65 # cd /usr/src/sys/config
67 # cp GENERIC /root/kernels/MYKERNEL
68 # ln -s /root/kernels/MYKERNEL
70 **Note:** You must execute these and all of the following commands under the `root` account or you will get permission denied errors.
72 Now, edit `MYKERNEL` with your favorite text editor. If you are just starting out, the only editor available will probably be ***vi***, which is too complex to explain here, but is covered well in many books in the [bibliography](bibliography.html). However, DragonFly does offer an easier editor called ***ee*** which, if you are a beginner, should be your editor of choice. Feel free to change the comment lines at the top to reflect your configuration or the changes you have made to differentiate it from `GENERIC`.
74 If you have built a kernel under SunOS™ or some other BSD operating system, much of this file will be very familiar to you. If you are coming from some other operating system such as DOS, on the other hand, the `GENERIC` configuration file might seem overwhelming to you, so follow the descriptions in the [[Configuration File|handbook-kernelconfig-config]] section slowly and carefully.
76 ### Building a Kernel - Full Source Tree
78 **Note:** Be sure to always check the file `/usr/src/UPDATING`, before you perform any update steps, in the case you [sync your source tree](updating.html#UPDATING-SETUP) with the latest sources of the DragonFly project. In this file all important issues with updating DragonFly are typed out. `/usr/src/UPDATING` always fits your version of the DragonFly source, and is therefore more accurate for new information than the handbook.
80 1. Change to the `/usr/src` directory.
86 1. Compile the kernel.
88 # make buildkernel KERNCONF=MYKERNEL
90 1. Install the new kernel.
92 # make installkernel KERNCONF=MYKERNEL
96 If you have ***not*** upgraded your source tree in any way since the last time you successfully completed a `buildworld`-`installworld` cycle (you have not run `git pull` ), then it is safe to use the `quickworld` and `quickkernel`, `buildworld`, `buildkernel` sequence.
98 ### Building a Kernel - Kernel Source Only
100 When only the kernel source is installed, you need to change step 2, above, to this:
103 # make nativekernel KERNCONF=MYKERNEL
105 The other steps are the same.
107 ### Running Your New Kernel
109 The installer copies the new kernel and modules to `/boot/kernel/`, the kernel being `/boot/kernel/kernel` and the modules being `/boot/kernel/*.ko`. The old kernel and modules are moved to `/boot/kernel.old/`. Now, shutdown the system and reboot to use your new kernel. In case something goes wrong, there are some [troubleshooting](kernelconfig-trouble.html) instructions at the end of this chapter. Be sure to read the section which explains how to recover in case your new kernel [does not boot](kernelconfig-trouble.html#KERNELCONFIG-NOBOOT).
111 **Note:** If you have added any new devices (such as sound cards), you may have to add some device nodes to your `/dev` directory before you can use them. For more information, take a look at device nodes section later on in this chapter.
113 ## The Configuration File
114 <!-- XXX: do we really want to mention all these million config options? -->
115 The general format of a configuration file is quite simple. Each line contains a keyword and one or more arguments. For simplicity, most lines only contain one argument. Anything following a `#` is considered a comment and ignored. The following sections describe each keyword, generally in the order they are listed in `GENERIC`, although some related keywords have been grouped together in a single section (such as Networking) even though they are actually scattered throughout the `GENERIC` file. An exhaustive list of options and more detailed explanations of the device lines is present in the `LINT` configuration file, located in the same directory as `GENERIC`. If you are in doubt as to the purpose or necessity of a line, check first in `LINT`.
117 The following is an example `GENERIC` kernel configuration file with various additional comments where needed for clarity. This example should match your copy in `/usr/src/sys/config/GENERIC` fairly closely. For details of all the possible kernel options, see `/usr/src/sys/config/LINT`.
125 # GENERIC -- Generic kernel configuration file for DragonFly/i386
129 # Check the LINT configuration file in sys/config, for an
131 # exhaustive list of options.
135 # $DragonFly: src/sys/config/GENERIC,v 1.56 2007/12/26 14:02:36 sephe Exp $
137 The following are the mandatory keywords required in ***every*** kernel you build:
143 This is the machine architecture. It must be `i386` at the moment. Support for `amd64` will be added in the future.
155 The above option specifies the type of CPU you have in your system. You may have multiple instances of the CPU line (i.e., you are not sure whether you should use `I586_CPU` or `I686_CPU`), however, for a custom kernel, it is best to specify only the CPU you have. If you are unsure of your CPU type, you can check the `/var/run/dmesg.boot` file to view your boot up messages.
161 This is the identification of the kernel. You should change this to whatever you named your kernel, i.e. `MYKERNEL` if you have followed the instructions of the previous examples. The value you put in the `ident` string will print when you boot up the kernel, so it is useful to give the new kernel a different name if you want to keep it separate from your usual kernel (i.e. you want to build an experimental kernel).
167 The `maxusers` option sets the size of a number of important system tables. This number is supposed to be roughly equal to the number of simultaneous users you expect to have on your machine.
169 (Recommended) The system will auto-tune this setting for you if you explicitly set it to `0`[(1)](#FTN.AEN7414). If you want to manage it yourself you will want to set `maxusers` to at least 4, especially if you are using the X Window System or compiling software. The reason is that the most important table set by `maxusers` is the maximum number of processes, which is set to `20 + 16 * maxusers`, so if you set `maxusers` to 1, then you can only have 36 simultaneous processes, including the 18 or so that the system starts up at boot time, and the 15 or so you will probably create when you start the X Window System. Even a simple task like reading a manual page will start up nine processes to filter, decompress, and view it. Setting `maxusers` to 64 will allow you to have up to 1044 simultaneous processes, which should be enough for nearly all uses. If, however, you see the dreaded proc table full error when trying to start another program, or are running a server with a large number of simultaneous users, you can always increase the number and rebuild.
171 **Note:** `maxusers` does ***not*** limit the number of users which can log into your machine. It simply sets various table sizes to reasonable values considering the maximum number of users you will likely have on your system and how many processes each of them will be running. One keyword which ***does*** limit the number of simultaneous ***remote logins and X terminal windows*** is [kernelconfig-config.html#KERNELCONFIG-PTYS `pseudo-device pty 16`].
175 # Floating point support - do not disable.
177 device npx0 at nexus? port IO_NPX irq 13
179 `npx0` is the interface to the floating point math unit in DragonFly, which is either the hardware co-processor or the software math emulator. This is ***not*** optional.
183 # Pseudo devices - the number indicates how many units to allocate.
185 pseudo-device loop # Network loopback
187 This is the generic loopback device for TCP/IP. If you telnet or FTP to `localhost` (a.k.a., `127.0.0.1`) it will come back at you through this device. This is ***mandatory***.
189 Everything that follows is more or less optional. See the notes underneath or next to each option for more information.
193 #makeoptions DEBUG=-g #Build kernel with gdb(1) debug symbols
195 The normal build process of the DragonFly does not include debugging information when building the kernel and strips most symbols after the resulting kernel is linked, to save some space at the install location. If you are going to do tests of kernels in the DEVELOPMENT branch or develop changes of your own for the DragonFly kernel, you might want to uncomment this line. It will enable the use of the `-g` option which enables debugging information when passed to [gcc(1)](http://leaf.dragonflybsd.org/cgi/web-man?command#gcc§ion1).
199 options MATH_EMULATE #Support for x87 emulation
201 This line allows the kernel to simulate a math co-processor if your computer does not have one (386 or 486SX). If you have a 486DX, or a 386 or 486SX (with a separate 387 or 487 chip), or higher (Pentium®, Pentium II, etc.), you can comment this line out.
203 **Note:** The normal math co-processor emulation routines that come with DragonFly are ***not*** very accurate. If you do not have a math co-processor, and you need the best accuracy, it is recommended that you change this option to `GPL_MATH_EMULATE` to use the GNU math support, which is not included by default for licensing reasons.
207 options INET #InterNETworking
209 Networking support. Leave this in, even if you do not plan to be connected to a network. Most programs require at least loopback networking (i.e., making network connections within your PC), so this is essentially mandatory.
213 options INET6 #IPv6 communications protocols
215 This enables the IPv6 communication protocols.
219 options FFS #Berkeley Fast Filesystem
221 options FFS_ROOT #FFS usable as root device [keep this!]
223 This is the basic hard drive Filesystem. Leave it in if you boot from the hard disk.
227 options UFS_DIRHASH #Improve performance on big directories
229 This option includes functionality to speed up disk operations on large directories, at the expense of using additional memory. You would normally keep this for a large server, or interactive workstation, and remove it if you are using DragonFly on a smaller system where memory is at a premium and disk access speed is less important, such as a firewall.
233 options SOFTUPDATES #Enable FFS Soft Updates support
235 This option enables Soft Updates in the kernel, this will help speed up write access on the disks. Even when this functionality is provided by the kernel, it must be turned on for specific disks. Review the output from [mount(8)](http://leaf.dragonflybsd.org/cgi/web-man?command#mount§ion8) to see if Soft Updates is enabled for your system disks. If you do not see the `soft-updates` option then you will need to activate it using the [tunefs(8)](http://leaf.dragonflybsd.org/cgi/web-man?command=tunefs§ion=8) (for existing filesystems) or [newfs(8)](http://leaf.dragonflybsd.org/cgi/web-man?command=newfs§ion=8) (for new filesystems) commands.
239 options MFS #Memory Filesystem
241 options MD_ROOT #MD is a potential root device
243 This is the memory-mapped filesystem. This is basically a RAM disk for fast storage of temporary files, useful if you have a lot of swap space that you want to take advantage of. A perfect place to mount an MFS partition is on the `/tmp` directory, since many programs store temporary data here. To mount an MFS RAM disk on `/tmp`, add the following line to `/etc/fstab`:
247 /dev/ad1s2b /tmp mfs rw 0 0
249 Now you simply need to either reboot, or run the command `mount /tmp`.
253 options NFS #Network Filesystem
255 options NFS_ROOT #NFS usable as root device, NFS required
257 The network Filesystem. Unless you plan to mount partitions from a UNIX® file server over TCP/IP, you can comment these out.
261 options MSDOSFS #MSDOS Filesystem
263 The MS-DOS® Filesystem. Unless you plan to mount a DOS formatted hard drive partition at boot time, you can safely comment this out. It will be automatically loaded the first time you mount a DOS partition, as described above. Also, the excellent ***mtools*** software (in pkgsrc®) allows you to access DOS floppies without having to mount and unmount them (and does not require `MSDOSFS` at all).
267 options CD9660 #ISO 9660 Filesystem
269 options CD9660_ROOT #CD-ROM usable as root, CD9660 required
271 The ISO 9660 Filesystem for CDROMs. Comment it out if you do not have a CDROM drive or only mount data CDs occasionally (since it will be dynamically loaded the first time you mount a data CD). Audio CDs do not need this Filesystem.
275 options PROCFS #Process filesystem
277 The process filesystem. This is a ***pretend*** filesystem mounted on `/proc` which allows programs like [ps(1)](http://leaf.dragonflybsd.org/cgi/web-man?command#ps§ion1) to give you more information on what processes are running. ***
281 Compatibility with 4.3BSD. Leave this in; some programs will act strangely if you comment this out.
285 options SCSI_DELAY=5000 #Delay (in ms) before probing SCSI
287 This causes the kernel to pause for 15 seconds before probing each SCSI device in your system. If you only have IDE hard drives, you can ignore this, otherwise you will probably want to lower this number, perhaps to five seconds (5000 ms), to speed up booting. Of course, if you do this, and DragonFly has trouble recognizing your SCSI devices, you will have to raise it back up.
291 options UCONSOLE #Allow users to grab the console
293 Allow users to grab the console, which is useful for X users. For example, you can create a console ***xterm*** by typing `xterm -C`, which will display any [write(1)](http://leaf.dragonflybsd.org/cgi/web-man?command#write§ion1), [talk(1)](http://leaf.dragonflybsd.org/cgi/web-man?command=talk§ion=1), and any other messages you receive, as well as any console messages sent by the kernel.
297 options USERCONFIG #boot -c editor
299 This option allows you to boot the configuration editor from the boot menu.
303 options VISUAL_USERCONFIG #visual boot -c editor
305 This option allows you to boot the visual configuration editor from the boot menu.
309 options KTRACE #ktrace(1) support
311 This enables kernel process tracing, which is useful in debugging.
315 options SYSVSHM #SYSV-style shared memory
317 This option provides for System V shared memory. The most common use of this is the XSHM extension in X, which many graphics-intensive programs will automatically take advantage of for extra speed. If you use X, you will definitely want to include this.
321 options SYSVSEM #SYSV-style semaphores
323 Support for System V semaphores. Less commonly used but only adds a few hundred bytes to the kernel.
327 options SYSVMSG #SYSV-style message queues
329 Support for System V messages. Again, only adds a few hundred bytes to the kernel.
331 **Note:** The [ipcs(1)](http://leaf.dragonflybsd.org/cgi/web-man?command#ipcs§ion1) command will list any processes using each of these System V facilities.
335 options P1003_1B #Posix P1003_1B real-time extensions
337 options _KPOSIX_PRIORITY_SCHEDULING
339 Real-time extensions added in the 1993 POSIX®. Certain applications in the ports collection use these (such as **StarOffice™** ).
343 options ICMP_BANDLIM #Rate limit bad replies
345 This option enables ICMP error response bandwidth limiting. You typically want this option as it will help protect the machine from denial of service packet attacks.
349 # To make an SMP kernel, the next two are needed
351 #options SMP # Symmetric MultiProcessor Kernel
353 #options APIC_IO # Symmetric (APIC) I/O
355 The above are both required for SMP support.
361 All PCs supported by DragonFly have one of these. Do not remove, even if you have no ISA slots. If you have an IBM PS/2 (Micro Channel Architecture), DragonFly provides some limited support at this time. For more information about the MCA support, see `/usr/src/sys/config/LINT`.
367 Include this if you have an EISA motherboard. This enables auto-detection and configuration support for all devices on the EISA bus.
373 Include this if you have a PCI motherboard. This enables auto-detection of PCI cards and gatewaying from the PCI to ISA bus.
379 Include this if you have an AGP card in the system. This will enable support for AGP, and AGP GART for boards which have these features.
385 device fdc0 at isa? port IO_FD1 irq 6 drq 2
387 device fd0 at fdc0 drive 0
389 device fd1 at fdc0 drive 1
391 This is the floppy drive controller. `fd0` is the `A:` floppy drive, and `fd1` is the `B:` drive.
397 This driver supports all ATA and ATAPI devices. You only need one `device ata` line for the kernel to detect all PCI ATA/ATAPI devices on modern machines.
401 device atadisk # ATA disk drives
403 This is needed along with `device ata` for ATA disk drives.
407 device atapicd # ATAPI CDROM drives
409 This is needed along with `device ata` for ATAPI CDROM drives.
413 device atapifd # ATAPI floppy drives
415 This is needed along with `device ata` for ATAPI floppy drives.
419 device atapist # ATAPI tape drives
421 This is needed along with `device ata` for ATAPI tape drives.
425 options ATA_STATIC_ID #Static device numbering
427 This makes the controller number static (like the old driver) or else the device numbers are dynamically allocated.
431 # ATA and ATAPI devices
433 device ata0 at isa? port IO_WD1 irq 14
435 device ata1 at isa? port IO_WD2 irq 15
437 Use the above for older, non-PCI systems.
443 device ahb # EISA AHA1742 family
445 device ahc # AHA2940 and onboard AIC7xxx devices
447 device amd # AMD 53C974 (Teckram DC-390(T))
449 device dpt # DPT Smartcache - See LINT for options!
451 device isp # Qlogic family
453 device ncr # NCR/Symbios Logic
455 device sym # NCR/Symbios Logic (newer chipsets)
467 SCSI controllers. Comment out any you do not have in your system. If you have an IDE only system, you can remove these altogether.
473 device scbus # SCSI bus (required)
475 device da # Direct Access (disks)
477 device sa # Sequential Access (tape etc)
481 device pass # Passthrough device (direct SCSI
485 SCSI peripherals. Again, comment out any you do not have, or if you have only IDE hardware, you can remove them completely.
487 **Note:** The USB [umass(4)](http://leaf.dragonflybsd.org/cgi/web-man?command#umass§ion4) driver (and a few other drivers) use the SCSI subsystem even though they are not real SCSI devices. Therefore make sure not to remove SCSI support, if any such drivers are included in the kernel configuration.
493 device ida # Compaq Smart RAID
495 device amr # AMI MegaRAID
497 device mlx # Mylex DAC960 family
499 Supported RAID controllers. If you do not have any of these, you can comment them out or remove them.
503 # atkbdc0 controls both the keyboard and the PS/2 mouse
505 device atkbdc0 at isa? port IO_KBD
507 The keyboard controller (`atkbdc`) provides I/O services for the AT keyboard and PS/2 style pointing devices. This controller is required by the keyboard driver (`atkbd`) and the PS/2 pointing device driver (`psm`).
511 device atkbd0 at atkbdc? irq 1
513 The `atkbd` driver, together with `atkbdc` controller, provides access to the AT 84 keyboard or the AT enhanced keyboard which is connected to the AT keyboard controller.
517 device psm0 at atkbdc? irq 12
519 Use this device if your mouse plugs into the PS/2 mouse port.
525 The video card driver.
529 # splash screen/screen saver
533 Splash screen at start up! Screen savers require this too.
537 # syscons is the default console driver, resembling an SCO console
541 `sc0` is the default console driver, which resembles a SCO console. Since most full-screen programs access the console through a terminal database library like `termcap`, it should not matter whether you use this or `vt0`, the `VT220` compatible console driver. When you log in, set your `TERM` variable to `scoansi` if full-screen programs have trouble running under this console.
545 # Enable this and PCVT_FREEBSD for pcvt vt220 compatible console driver
549 #options XSERVER # support for X server on a vt console
551 #options FAT_CURSOR # start with block cursor
553 # If you have a ThinkPAD, uncomment this along with the rest of the PCVT lines
555 #options PCVT_SCANSET=2 # IBM keyboards are non-std
557 This is a VT220-compatible console driver, backward compatible to VT100/102. It works well on some laptops which have hardware incompatibilities with `sc0`. Also set your `TERM` variable to `vt100` or `vt220` when you log in. This driver might also prove useful when connecting to a large number of different machines over the network, where `termcap` or `terminfo` entries for the `sc0` device are often not available -- `vt100` should be available on virtually any platform.
561 # Power management support (see LINT for more options)
563 device apm0 at nexus? disable flags 0x20 # Advanced Power Management
565 Advanced Power Management support. Useful for laptops.
569 # PCCARD (PCMCIA) support
573 device pcic0 at isa? irq 10 port 0x3e0 iomem 0xd0000
575 device pcic1 at isa? irq 11 port 0x3e2 iomem 0xd4000 disable
577 PCMCIA support. You want this if you are using a laptop.
583 device sio0 at isa? port IO_COM1 flags 0x10 irq 4
585 device sio1 at isa? port IO_COM2 irq 3
587 device sio2 at isa? disable port IO_COM3 irq 5
589 device sio3 at isa? disable port IO_COM4 irq 9
591 These are the four serial ports referred to as COM1 through COM4 in the MS-DOS/Windows® world.
593 **Note:** If you have an internal modem on COM4 and a serial port at COM2, you will have to change the IRQ of the modem to 2 (for obscure technical reasons, IRQ2 # IRQ 9) in order to access it from DragonFly. If you have a multiport serial card, check the manual page for [sio(4)](http://leaf.dragonflybsd.org/cgi/web-man?commandsio§ion=4) for more information on the proper values for these lines. Some video cards (notably those based on S3 chips) use IO addresses in the form of `0x*2e8`, and since many cheap serial cards do not fully decode the 16-bit IO address space, they clash with these cards making the COM4 port practically unavailable.
595 Each serial port is required to have a unique IRQ (unless you are using one of the multiport cards where shared interrupts are supported), so the default IRQs for COM3 and COM4 cannot be used.
601 device ppc0 at isa? irq 7
603 This is the ISA-bus parallel port interface.
607 device ppbus # Parallel port bus (required)
609 Provides support for the parallel port bus.
615 Support for parallel port printers.
617 **Note:** All three of the above are required to enable parallel printer support.
621 device plip # TCP/IP over parallel
623 This is the driver for the parallel network interface.
627 device ppi # Parallel port interface device
629 The general-purpose I/O (***geek port) + IEEE1284 I/O.
633 #device vpo # Requires scbus and da
635 This is for an Iomega Zip drive. It requires `scbus` and `da` support. Best performance is achieved with ports in EPP 1.9 mode.
641 device de # DEC/Intel DC21x4x (Tulip)
643 device fxp # Intel EtherExpress PRO/100B (82557, 82558)
645 device tx # SMC 9432TX (83c170 EPIC)
647 device vx # 3Com 3c590, 3c595 (Vortex)
649 device wx # Intel Gigabit Ethernet Card (Wiseman)
651 Various PCI network card drivers. Comment out or remove any of these not present in your system.
655 # PCI Ethernet NICs that use the common MII bus controller code.
657 device miibus # MII bus support
659 MII bus support is required for some PCI 10/100 Ethernet NICs, namely those which use MII-compliant transceivers or implement transceiver control interfaces that operate like an MII. Adding `device miibus` to the kernel config pulls in support for the generic miibus API and all of the PHY drivers, including a generic one for PHYs that are not specifically handled by an individual driver.
663 device dc # DEC/Intel 21143 and various workalikes
665 device rl # RealTek 8129/8139
667 device sf # Adaptec AIC-6915 (Starfire)
669 device sis # Silicon Integrated Systems SiS 900/SiS 7016
671 device ste # Sundance ST201 (D-Link DFE-550TX)
673 device tl # Texas Instruments ThunderLAN
675 device vr # VIA Rhine, Rhine II
677 device wb # Winbond W89C840F
679 device xl # 3Com 3c90x (Boomerang, Cyclone)
681 Drivers that use the MII bus controller code.
687 device ed0 at isa? port 0x280 irq 10 iomem 0xd8000
693 # WaveLAN/IEEE 802.11 wireless NICs. Note: the WaveLAN/IEEE really
695 # exists only as a PCMCIA device, so there is no ISA attachment needed
697 # and resources will always be dynamically assigned by the pccard code.
701 # Aironet 4500/4800 802.11 wireless NICs. Note: the declaration below will
703 # work for PCMCIA and PCI cards, as well as ISA cards set to ISA PnP
705 # mode (the factory default). If you set the switches on your ISA
707 # card for a manually chosen I/O address and IRQ, you must specify
709 # those parameters here.
713 # The probe order of these is presently determined by i386/isa/isa_compat.c.
715 device ie0 at isa? port 0x300 irq 10 iomem 0xd0000
717 device fe0 at isa? port 0x300
719 device le0 at isa? port 0x300 irq 5 iomem 0xd0000
721 device lnc0 at isa? port 0x280 irq 10 drq 0
723 device cs0 at isa? port 0x300
725 device sn0 at isa? port 0x300 irq 10
727 # requires PCCARD (PCMCIA) support to be activated
731 ISA Ethernet drivers. See `/usr/src/sys/config/LINT` for which cards are supported by which driver.
735 pseudo-device ether # Ethernet support
737 `ether` is only needed if you have an Ethernet card. It includes generic Ethernet protocol code.
741 pseudo-device sl 1 # Kernel SLIP
743 `sl` is for SLIP support. This has been almost entirely supplanted by PPP, which is easier to set up, better suited for modem-to-modem connection, and more powerful. The ***number*** after `sl` specifies how many simultaneous SLIP sessions to support.
747 pseudo-device ppp 1 # Kernel PPP
749 This is for kernel PPP support for dial-up connections. There is also a version of PPP implemented as a userland application that uses `tun` and offers more flexibility and features such as demand dialing. The ***number*** after `ppp` specifies how many simultaneous PPP connections to support. .
753 device tun # Packet tunnel.
755 This is used by the userland PPP software. A ***number*** after `tun` specifies the number of simultaneous PPP sessions to support. See the [userppp.html PPP] section of this book for more information.
759 pseudo-device pty # Pseudo-ttys (telnet etc)
761 This is a ***pseudo-terminal*** or simulated login port. It is used by incoming `telnet` and `rlogin` sessions, ***xterm***, and some other applications such as ***Emacs***. The ***number*** after `pty` indicates the number of `pty`s to create. If you need more than the default of 16 simultaneous ***xterm*** windows and/or remote logins, be sure to increase this number accordingly, up to a maximum of 256. ***
765 Memory disk pseudo-devices.
769 pseudo-device gif # IPv6 and IPv4 tunneling
771 This implements IPv6 over IPv4 tunneling, IPv4 over IPv6 tunneling, IPv4 over IPv4 tunneling, and IPv6 over IPv6 tunneling.
775 pseudo-device faith # IPv6-to-IPv4 relaying (translation)
777 This pseudo-device captures packets that are sent to it and diverts them to the IPv4/IPv6 translation daemon.
781 # The `bpf' device enables the Berkeley Packet Filter.
783 # Be aware of the administrative consequences of enabling this!
785 pseudo-device bpf # Berkeley packet filter
787 This is the Berkeley Packet Filter. This pseudo-device allows network interfaces to be placed in promiscuous mode, capturing every packet on a broadcast network (e.g., an Ethernet). These packets can be captured to disk and or examined with the [tcpdump(1)](http://leaf.dragonflybsd.org/cgi/web-man?command#tcpdump§ion1) program.
789 **Note:** The [bpf(4)](http://leaf.dragonflybsd.org/cgi/web-man?command#bpf§ion4) device is also used by [dhclient(8)](http://leaf.dragonflybsd.org/cgi/web-man?command=dhclient§ion=8) to obtain the IP address of the default router (gateway) and so on. If you use DHCP, leave this uncommented.
795 #device uhci # UHCI PCI->USB interface
797 #device ohci # OHCI PCI->USB interface
799 #device usb # USB Bus (required)
801 #device ugen # Generic
803 #device uhid # ***Human Interface Devices***
805 #device ukbd # Keyboard
807 #device ulpt # Printer
809 #device umass # Disks/Mass storage - Requires scbus and da
813 # USB Ethernet, requires mii
815 #device aue # ADMtek USB ethernet
817 #device cue # CATC USB ethernet
819 #device kue # Kawasaki LSI USB ethernet
821 Support for various USB devices.
823 For more information and additional devices supported by DragonFly, see `/usr/src/sys/i386/conf/LINT`.
828 <tablewidth="100%"> [(1)](kernelconfig-config.html#AEN7414) | The auto-tuning algorithm sets `maxuser` equal to the amount of memory in the system, with a minimum of 32, and a maximum of 384. |
834 Almost every device in the kernel has a corresponding node entry in the `/dev` directory. These nodes look like regular files, but are actually special entries into the kernel which programs use to access the device.
836 These nodes are created automatically once devfs is mounted, which happens manually for the root `/dev` during boot, just after the root mount.
838 ## If Something Goes Wrong
840 **Note:** If you are having trouble building a kernel, make sure to keep a `GENERIC`, or some other kernel that is known to work on hand as a different name that will not get erased on the next build. You cannot rely on `kernel.old` because when installing a new kernel, `kernel.old` is overwritten with the last installed kernel which may be non-functional. Also, as soon as possible, move the working kernel to the proper `kernel` location or commands such as [ps(1)](http://leaf.dragonflybsd.org/cgi/web-man?command#ps§ion1) will not work properly. The proper command to ***unlock*** the kernel file that `make` installs (in order to move another kernel back permanently) is:
842 % chflags noschg /boot/kernel
845 If you find you cannot do this, you are probably running at a [securelevel(8)](http://leaf.dragonflybsd.org/cgi/web-man?command#securelevel§ion8) greater than zero. Edit `kern_securelevel` in `/etc/rc.conf` and set it to `-1`, then reboot. You can change it back to its previous setting when you are happy with your new kernel.
847 And, if you want to ***lock*** your new kernel into place, or any file for that matter, so that it cannot be moved or tampered with:
851 % chflags schg /boot/kernel
854 There are five categories of trouble that can occur when building a custom kernel. They are:
856 * `config` fails: If the [config(8)](http://leaf.dragonflybsd.org/cgi/web-man?command#config§ion8) command fails when you give it your kernel description, you have probably made a simple error somewhere. Fortunately, [config(8)](http://leaf.dragonflybsd.org/cgi/web-man?command=config§ion=8) will print the line number that it had trouble with, so you can quickly skip to it with ***vi***. For example, if you see `config: line 17: syntax error`. You can skip to the problem in ***vi*** by typing `17G` in command mode. Make sure the keyword is typed correctly, by comparing it to the `GENERIC` kernel or another reference.
858 * `make` fails: If the `make` command fails, it usually signals an error in your kernel description, but not severe enough for [config(8)](http://leaf.dragonflybsd.org/cgi/web-man?command#config§ion8) to catch it. Again, look over your configuration, and if you still cannot resolve the problem, send mail to the [DragonFly Bugs mailing list](http://leaf.dragonflybsd.org/mailarchive/) with your kernel configuration, and it should be diagnosed very quickly.
860 * Installing the new kernel fails: If the kernel compiled fine, but failed to install (the `make install` or `make installkernel` command failed), the first thing to check is if your system is running at securelevel 1 or higher (see [init(8)](http://leaf.dragonflybsd.org/cgi/web-man?command#init§ion8)). The kernel installation tries to remove the immutable flag from your kernel and set the immutable flag on the new one. Since securelevel 1 or higher prevents unsetting the immutable flag for any files on the system, the kernel installation needs to be performed at securelevel 0 or lower.
862 * The kernel does not boot: If your new kernel does not boot, or fails to recognize your devices, do not panic! Fortunately, DragonFly has an excellent mechanism for recovering from incompatible kernels. Simply choose the kernel you want to boot from at the DragonFly boot loader. You can access this when the system counts down from 10. Hit any key except for the **Enter** key, type `unload` and then type `boot ***kernel.old***`, or the filename of any other kernel that will boot properly. When reconfiguring a kernel, it is always a good idea to keep a kernel that is known to work on hand. After booting with a good kernel you can check over your configuration file and try to build it again. One helpful resource is the `/var/log/messages` file which records, among other things, all of the kernel messages from every successful boot. Also, the [dmesg(8)](http://leaf.dragonflybsd.org/cgi/web-man?command#dmesg§ion8) command will print the kernel messages from the current boot.
864 * The kernel works, but [ps(1)](http://leaf.dragonflybsd.org/cgi/web-man?command#ps§ion1) does not work any more: If you have installed a different version of the kernel from the one that the system utilities have been built with, many system-status commands like [ps(1)](http://leaf.dragonflybsd.org/cgi/web-man?command=ps§ion=1) and [vmstat(8)](http://leaf.dragonflybsd.org/cgi/web-man?command=vmstat§ion=8) will not work any more. You must recompile the `libkvm` library as well as these utilities. This is one reason it is not normally a good idea to use a different version of the kernel from the rest of the operating system.