June 1999 Kernel Parameters v2.2.9 ~~~~~~~~~~~~~~~~~ The following is a consolidated list of the kernel parameters as defined in the file init/main.c and sorted into English Dictionary order (defined as ignoring all punctuation and sorting digits before letters in a case insensitive manner), and with descriptions where known. The text in square brackets at the beginning of the description state the restrictions on the kernel for the said kernel parameter to be valid. The restrictions referred to are that the relevant option is valid if: APIC APIC support is enabled. APM Advanced Power Management support is enabled. AX25 Appropriate AX.25 support is enabled. CD Appropriate CD support is enabled. EIDE EIDE/ATAPI support is enabled. FB The frame buffer device is enabled. HW Appropriate hardware is enabled. ISDN Appropriate ISDN support is enabled. JOY Appropriate joystick support is enabled. LP Printer support is enabled. LOOP Loopback device support is enabled. MCA MCA bus support is enabled. MDA MDA console support is enabled. MOUSE Appropriate mouse support is enabled. NET Appropriate network support is enabled. NFS Appropriate NFS support is enabled. PARIDE The ParIDE subsystem is enabled. PCI PCI bus support is enabled. PCMCIA The PCMCIA subsystem is enabled. PNP Plug & Play support is enabled. PPT Parallel port support is enabled. PS2 Appropriate PS/2 support is enabled. RAM RAM disk support is enabled. SCSI Appropriate SCSI support is enabled. SERIAL Serial support is enabled. SMP The kernel is an SMP kernel. SOUND Appropriate sound system support is enabled. VGA The VGA console has been enabled. VT Virtual terminal support is enabled. XT IBM PC/XT MFM hard disk support is enabled. In addition, the following text indicates that the option: BUGS= Relates to possible processor bugs on the said processor. KNL Is a kernel start-up parameter. Note that ALL kernel parameters listed below are CASE SENSITIVE, and that a trailing = on the name of any parameter states that that parameter will be entered as an environment variable, whereas its absence indicates that it will appear as a kernel argument readable via /proc/cmdline by programs running once the system is up. 53c7xx= [HW,SCSI] Amiga SCSI controllers. adb_buttons= [HW,MOUSE] advansys= [HW,SCSI] aha152x= [HW,SCSI] aha1542= [HW,SCSI] aic7xxx= [HW,SCSI] AM53C974= [HW,SCSI] apm= [APM] Advanced Power Management. arcrimi= [HW,NET] ataflop= [HW, M68k] atamouse= [HW,MOUSE] Atari Mouse. atascsi= [HW,SCSI] Atari SCSI. aztcd= [HW,CD] Aztec CD driver. baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem. baycom_ser_fdx= [HW,AX25] BayCom Serial Port AX.25 Modem in Full Duplex Mode. baycom_ser_hdx= [HW,AX25] BayCom Serial Port AX.25 Modem in Half Duplex Mode. bmouse= [HW,MOUSE,PS2] Bus mouse. BusLogic= [HW,SCSI] cdu31a= [HW,CD] cm206= [HW,CD] com20020= [HW,NET] com90io= [HW,NET] com90xx= [HW,NET] console= [KNL] output console + comm spec (speed, control, parity). cyclades= [HW,SERIAL] Cyclades multi-serial port adapter. debug [KNL] Enable kernel debugging (events log level). decnet= [HW,NET] digi= [HW,SERIAL] io parameters + enable/disable command. digiepca= [HW,SERIAL] dmascc= [HW,AX25,SERIAL] AX.25 Z80SCC driver with DMA support available. dmasound= [HW,SOUND] (sound subsystem buffers). dtc3181e= [HW,SCSI] eata= [HW,SCSI] eda= [HW,PS2] edb= [HW,PS2] ether= [HW,NET] Ethernet cards parameters (iomem, irq, dev_name). fd_mcs= [HW,SCSI] fdomain= [HW,SCSI] floppy= [HW] ftape= [HW] Floppy Tape subsystem debugging options. gdth= [HW,SCSI] gscd= [HW,CD] gvp11= [HW,SCSI] hd= [EIDE] (E)IDE hard drive subsystem geometry (Cyl/heads/sectors) or tune parameters. hfmodem= [HW,AX25] HiSax= [HW,ISDN] hisax= [HW,ISDN] in2000= [HW,SCSI] init= [KNL] ibmmcascsi= [HW,MCA,SCSI] IBM MicroChannel SCSI adapter. icn= [HW,ISDN] ide?= [HW] (E)IDE subsystem : config (iomem/irq), tuning or debugging (serialize,reset,no{dma,tune,probe}) or chipset specific parameters. idebus= [HW] (E)IDE subsystem : VLB/PCI bus speed. in2000= [HW,SCSI] init= [KNL] Default init level. ip= [PNP] isp16= [HW,CD] js_14= [HW,JOY] js_am= [HW,JOY] js_an= [HW,JOY] js_as= [HW.JOY] js_console= [HW,JOY] js_console2= [HW,JOY] js_console3= [HW,JOY] js_db9= [HW,JOY] js_db9_2= [HW,JOY] js_db9_3= [HW,JOY] js_tg= [HW,JOY] js_tg_2= [HW,JOY] js_tg_3= [HW,JOY] kbd-reset [VT] load_ramdisk= [RAM] List of ramdisks to load from floppy. lp=0 [LP] Specify parallel ports to use, e.g, lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses lp=reset first parallel port). 'lp=0' disables the lp=auto printer driver. 'lp=reset' (which can be specified in addition to the ports) causes attached printers to be reset. Using lp=port1,port2,... specifies the parallel ports to associate lp devices with, starting with lp0. A port specification may be 'none' to skip that lp device, or a parport name such as 'parport0'. Specifying 'lp=auto' instead of a port specification list means that device IDs from each port should be examined, to see if an IEEE 1284-compliant printer is attached; if so, the driver will manage that printer. ltpc= [HW] mac5380= [HW,SCSI] max_loop=[0-255] [LOOP] Set the maximum number of loopback devices that can be mounted. maxcpus= [SMP] States the maximum number of processors that an SMP kernel should make use of. max_scsi_luns= [SCSI] mca-pentium [BUGS=ix86] mcd= [HW,CD] mcdx= [HW,CD] md= [HW] RAID subsystems devices and level. mdacon= [MDA] mem= [KNL] force use XX Mb of memory when the kernel is not able to see the whole system memory or for test. msmouse= [HW,MOUSE] Microsoft Mouse. ncr5380= [HW,SCSI] ncr53c400= [HW,SCSI] ncr53c400a= [HW,SCSI] ncr53c406a= [HW,SCSI] ncr53c8xx= [HW,SCSI] nfsaddrs= [NFS] nfsroot= [NFS] nfs root filesystem for disk-less boxes. nmi_watchdog= [KNL, BUGS=ix86] debugging features for SMP kernels. no387 [BUGS=ix86] Tells the kernel to use the 387 maths emulation library even if a 387 maths coprocessor is present. noapic [SMP,APIC] Tells the kernel not to make use of any APIC that may be present on the system. noasync [HW, M68K] Disables async and sync negotiation for all devices. nodisconnect [HW,SCSI, M68K] Disables SCSI disconnects. no-halt [BUGS=ix86] noinitrd [RAM] Tells the kernel not to load any configured initial RAM disk. no-scroll [VGA] nosmp [SMP] Tells an SMP kernel to act as a UP kernel. nosync [HW, M68K] Disables sync negotiation for all devices. optcd= [HW,CD] panic= [KNL] kernel behaviour on panic. parport=0 [HW,PPT] Specify parallel ports. 0 disables. parport=auto Use 'auto' to force the driver to use parport=0xBBB[,IRQ[,DMA]] any IRQ/DMA settings detected (the default is to ignore detected IRQ/DMA settings because of possible conflicts). You can specify the base address, IRQ, and DMA settings; IRQ and DMA should be numbers, or 'auto' (for using detected settings on that particular port), or 'nofifo' (to avoid using a FIFO even if it is detected). Parallel ports are assigned in the order they are specified on the command line, starting with parport0. pas16= [HW,SCSI] pcbit= [HW,ISDN] pcd. [PARIDE] pci= [PCI] pd. [PARIDE] pf. [PARIDE] pg. [PARIDE] pirq= [SMP,APIC] mp-table. plip= [PPT,NET] Parallel port network link. profile= [KNL] enable kernel profiling via /proc/profile (param:log level). prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk before loading. pt. [PARIDE] ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]. ramdisk_size= [RAM] New name for the ramdisk parameter. ramdisk_start= [RAM] Starting block of RAM disk image (so you can place it after the kernel image on a boot floppy). reboot= [BUGS=ix86] reserve= [KNL,BUGS] force the kernel to ignore some iomem area. riscom8= [HW,SERIAL] ro [KNL] Mount root device read-only on boot. root= [KNL] root filesystem. rw [KNL] Mount root device read-write on boot. S [KNL] run init in single mode. sbpcd= [HW,CD] Soundblaster CD adapter. scsi_logging= [SCSI] sjcd= [HW,CD] sonycd535= [HW,CD] sound= [SOUND] soundmodem= [HW,AX25,SOUND] Use sound card as packet radio modem. specialix= [HW,SERIAL] Specialix multi-serial port adapter. st= [HW] SCSI tape parameters (buffers, etc.). st0x= [HW,SCSI] stram_swap= [HW] switches= [HW, M68K] sym53c416= [HW,SCSI] sym53c8xx= [HW,SCSI] t128= [HW,SCSI] tmc8xx= [HW,SCSI] tmscsim= [HW,SCSI] tp720= [HW,PS2] u14-34f= [HW,SCSI] video= [FB] frame buffer configuration. vga= [KNL] on ix386, enable to choose a peculiar video mode (use vga=ask for menu). wd33c93= [HW,SCSI] wd7000= [HW,SCSI] wdt= [HW] xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks. xd_geo= [HW,XT]