1=================================== 2Command Line Options for Linux/m68k 3=================================== 4 5Last Update: 2 May 1999 6 7Linux/m68k version: 2.2.6 8 9Author: Roman.Hodek@informatik.uni-erlangen.de (Roman Hodek) 10 11Update: jds@kom.auc.dk (Jes Sorensen) and faq@linux-m68k.org (Chris Lawrence) 12 130) Introduction 14=============== 15 16Often I've been asked which command line options the Linux/m68k 17kernel understands, or how the exact syntax for the ... option is, or 18... about the option ... . I hope, this document supplies all the 19answers... 20 21Note that some options might be outdated, their descriptions being 22incomplete or missing. Please update the information and send in the 23patches. 24 25 261) Overview of the Kernel's Option Processing 27============================================= 28 29The kernel knows three kinds of options on its command line: 30 31 1) kernel options 32 2) environment settings 33 3) arguments for init 34 35To which of these classes an argument belongs is determined as 36follows: If the option is known to the kernel itself, i.e. if the name 37(the part before the '=') or, in some cases, the whole argument string 38is known to the kernel, it belongs to class 1. Otherwise, if the 39argument contains an '=', it is of class 2, and the definition is put 40into init's environment. All other arguments are passed to init as 41command line options. 42 43This document describes the valid kernel options for Linux/m68k in 44the version mentioned at the start of this file. Later revisions may 45add new such options, and some may be missing in older versions. 46 47In general, the value (the part after the '=') of an option is a 48list of values separated by commas. The interpretation of these values 49is up to the driver that "owns" the option. This association of 50options with drivers is also the reason that some are further 51subdivided. 52 53 542) General Kernel Options 55========================= 56 572.1) root= 58---------- 59 60:Syntax: root=/dev/<device> 61:or: root=<hex_number> 62 63This tells the kernel which device it should mount as the root 64filesystem. The device must be a block device with a valid filesystem 65on it. 66 67The first syntax gives the device by name. These names are converted 68into a major/minor number internally in the kernel in an unusual way. 69Normally, this "conversion" is done by the device files in /dev, but 70this isn't possible here, because the root filesystem (with /dev) 71isn't mounted yet... So the kernel parses the name itself, with some 72hardcoded name to number mappings. The name must always be a 73combination of two or three letters, followed by a decimal number. 74Valid names are:: 75 76 /dev/ram: -> 0x0100 (initial ramdisk) 77 /dev/hda: -> 0x0300 (first IDE disk) 78 /dev/hdb: -> 0x0340 (second IDE disk) 79 /dev/sda: -> 0x0800 (first SCSI disk) 80 /dev/sdb: -> 0x0810 (second SCSI disk) 81 /dev/sdc: -> 0x0820 (third SCSI disk) 82 /dev/sdd: -> 0x0830 (forth SCSI disk) 83 /dev/sde: -> 0x0840 (fifth SCSI disk) 84 /dev/fd : -> 0x0200 (floppy disk) 85 86The name must be followed by a decimal number, that stands for the 87partition number. Internally, the value of the number is just 88added to the device number mentioned in the table above. The 89exceptions are /dev/ram and /dev/fd, where /dev/ram refers to an 90initial ramdisk loaded by your bootstrap program (please consult the 91instructions for your bootstrap program to find out how to load an 92initial ramdisk). As of kernel version 2.0.18 you must specify 93/dev/ram as the root device if you want to boot from an initial 94ramdisk. For the floppy devices, /dev/fd, the number stands for the 95floppy drive number (there are no partitions on floppy disks). I.e., 96/dev/fd0 stands for the first drive, /dev/fd1 for the second, and so 97on. Since the number is just added, you can also force the disk format 98by adding a number greater than 3. If you look into your /dev 99directory, use can see the /dev/fd0D720 has major 2 and minor 16. You 100can specify this device for the root FS by writing "root=/dev/fd16" on 101the kernel command line. 102 103[Strange and maybe uninteresting stuff ON] 104 105This unusual translation of device names has some strange 106consequences: If, for example, you have a symbolic link from /dev/fd 107to /dev/fd0D720 as an abbreviation for floppy driver #0 in DD format, 108you cannot use this name for specifying the root device, because the 109kernel cannot see this symlink before mounting the root FS and it 110isn't in the table above. If you use it, the root device will not be 111set at all, without an error message. Another example: You cannot use a 112partition on e.g. the sixth SCSI disk as the root filesystem, if you 113want to specify it by name. This is, because only the devices up to 114/dev/sde are in the table above, but not /dev/sdf. Although, you can 115use the sixth SCSI disk for the root FS, but you have to specify the 116device by number... (see below). Or, even more strange, you can use the 117fact that there is no range checking of the partition number, and your 118knowledge that each disk uses 16 minors, and write "root=/dev/sde17" 119(for /dev/sdf1). 120 121[Strange and maybe uninteresting stuff OFF] 122 123If the device containing your root partition isn't in the table 124above, you can also specify it by major and minor numbers. These are 125written in hex, with no prefix and no separator between. E.g., if you 126have a CD with contents appropriate as a root filesystem in the first 127SCSI CD-ROM drive, you boot from it by "root=0b00". Here, hex "0b" = 128decimal 11 is the major of SCSI CD-ROMs, and the minor 0 stands for 129the first of these. You can find out all valid major numbers by 130looking into include/linux/major.h. 131 132In addition to major and minor numbers, if the device containing your 133root partition uses a partition table format with unique partition 134identifiers, then you may use them. For instance, 135"root=PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF". It is also 136possible to reference another partition on the same device using a 137known partition UUID as the starting point. For example, 138if partition 5 of the device has the UUID of 13900112233-4455-6677-8899-AABBCCDDEEFF then partition 3 may be found as 140follows: 141 142 PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF/PARTNROFF=-2 143 144Authoritative information can be found in 145"Documentation/admin-guide/kernel-parameters.rst". 146 147 1482.2) ro, rw 149----------- 150 151:Syntax: ro 152:or: rw 153 154These two options tell the kernel whether it should mount the root 155filesystem read-only or read-write. The default is read-only, except 156for ramdisks, which default to read-write. 157 158 1592.3) debug 160---------- 161 162:Syntax: debug 163 164This raises the kernel log level to 10 (the default is 7). This is the 165same level as set by the "dmesg" command, just that the maximum level 166selectable by dmesg is 8. 167 168 1692.4) debug= 170----------- 171 172:Syntax: debug=<device> 173 174This option causes certain kernel messages be printed to the selected 175debugging device. This can aid debugging the kernel, since the 176messages can be captured and analyzed on some other machine. Which 177devices are possible depends on the machine type. There are no checks 178for the validity of the device name. If the device isn't implemented, 179nothing happens. 180 181Messages logged this way are in general stack dumps after kernel 182memory faults or bad kernel traps, and kernel panics. To be exact: all 183messages of level 0 (panic messages) and all messages printed while 184the log level is 8 or more (their level doesn't matter). Before stack 185dumps, the kernel sets the log level to 10 automatically. A level of 186at least 8 can also be set by the "debug" command line option (see 1872.3) and at run time with "dmesg -n 8". 188 189Devices possible for Amiga: 190 191 - "ser": 192 built-in serial port; parameters: 9600bps, 8N1 193 - "mem": 194 Save the messages to a reserved area in chip mem. After 195 rebooting, they can be read under AmigaOS with the tool 196 'dmesg'. 197 198Devices possible for Atari: 199 200 - "ser1": 201 ST-MFP serial port ("Modem1"); parameters: 9600bps, 8N1 202 - "ser2": 203 SCC channel B serial port ("Modem2"); parameters: 9600bps, 8N1 204 - "ser" : 205 default serial port 206 This is "ser2" for a Falcon, and "ser1" for any other machine 207 - "midi": 208 The MIDI port; parameters: 31250bps, 8N1 209 - "par" : 210 parallel port 211 212 The printing routine for this implements a timeout for the 213 case there's no printer connected (else the kernel would 214 lock up). The timeout is not exact, but usually a few 215 seconds. 216 217 2182.6) ramdisk_size= 219------------------ 220 221:Syntax: ramdisk_size=<size> 222 223This option instructs the kernel to set up a ramdisk of the given 224size in KBytes. Do not use this option if the ramdisk contents are 225passed by bootstrap! In this case, the size is selected automatically 226and should not be overwritten. 227 228The only application is for root filesystems on floppy disks, that 229should be loaded into memory. To do that, select the corresponding 230size of the disk as ramdisk size, and set the root device to the disk 231drive (with "root="). 232 233 2342.7) swap= 235 236 I can't find any sign of this option in 2.2.6. 237 2382.8) buff= 239----------- 240 241 I can't find any sign of this option in 2.2.6. 242 243 2443) General Device Options (Amiga and Atari) 245=========================================== 246 2473.1) hd= 248-------- 249 250:Syntax: hd=<cylinders>,<heads>,<sectors> 251 252This option sets the disk geometry of an IDE disk. The first hd= 253option is for the first IDE disk, the second for the second one. 254(I.e., you can give this option twice.) In most cases, you won't have 255to use this option, since the kernel can obtain the geometry data 256itself. It exists just for the case that this fails for one of your 257disks. 258 259 2603.2) max_scsi_luns= 261------------------- 262 263:Syntax: max_scsi_luns=<n> 264 265Sets the maximum number of LUNs (logical units) of SCSI devices to 266be scanned. Valid values for <n> are between 1 and 8. Default is 8 if 267"Probe all LUNs on each SCSI device" was selected during the kernel 268configuration, else 1. 269 270 2713.3) st= 272-------- 273 274:Syntax: st=<buffer_size>,[<write_thres>,[<max_buffers>]] 275 276Sets several parameters of the SCSI tape driver. <buffer_size> is 277the number of 512-byte buffers reserved for tape operations for each 278device. <write_thres> sets the number of blocks which must be filled 279to start an actual write operation to the tape. Maximum value is the 280total number of buffers. <max_buffer> limits the total number of 281buffers allocated for all tape devices. 282 283 2843.4) dmasound= 285-------------- 286 287:Syntax: dmasound=[<buffers>,<buffer-size>[,<catch-radius>]] 288 289This option controls some configurations of the Linux/m68k DMA sound 290driver (Amiga and Atari): <buffers> is the number of buffers you want 291to use (minimum 4, default 4), <buffer-size> is the size of each 292buffer in kilobytes (minimum 4, default 32) and <catch-radius> says 293how much percent of error will be tolerated when setting a frequency 294(maximum 10, default 0). For example with 3% you can play 8000Hz 295AU-Files on the Falcon with its hardware frequency of 8195Hz and thus 296don't need to expand the sound. 297 298 299 3004) Options for Atari Only 301========================= 302 3034.1) video= 304----------- 305 306:Syntax: video=<fbname>:<sub-options...> 307 308The <fbname> parameter specifies the name of the frame buffer, 309eg. most atari users will want to specify `atafb` here. The 310<sub-options> is a comma-separated list of the sub-options listed 311below. 312 313NB: 314 Please notice that this option was renamed from `atavideo` to 315 `video` during the development of the 1.3.x kernels, thus you 316 might need to update your boot-scripts if upgrading to 2.x from 317 an 1.2.x kernel. 318 319NBB: 320 The behavior of video= was changed in 2.1.57 so the recommended 321 option is to specify the name of the frame buffer. 322 3234.1.1) Video Mode 324----------------- 325 326This sub-option may be any of the predefined video modes, as listed 327in atari/atafb.c in the Linux/m68k source tree. The kernel will 328activate the given video mode at boot time and make it the default 329mode, if the hardware allows. Currently defined names are: 330 331 - stlow : 320x200x4 332 - stmid, default5 : 640x200x2 333 - sthigh, default4: 640x400x1 334 - ttlow : 320x480x8, TT only 335 - ttmid, default1 : 640x480x4, TT only 336 - tthigh, default2: 1280x960x1, TT only 337 - vga2 : 640x480x1, Falcon only 338 - vga4 : 640x480x2, Falcon only 339 - vga16, default3 : 640x480x4, Falcon only 340 - vga256 : 640x480x8, Falcon only 341 - falh2 : 896x608x1, Falcon only 342 - falh16 : 896x608x4, Falcon only 343 344If no video mode is given on the command line, the kernel tries the 345modes names "default<n>" in turn, until one is possible with the 346hardware in use. 347 348A video mode setting doesn't make sense, if the external driver is 349activated by a "external:" sub-option. 350 3514.1.2) inverse 352-------------- 353 354Invert the display. This affects only text consoles. 355Usually, the background is chosen to be black. With this 356option, you can make the background white. 357 3584.1.3) font 359----------- 360 361:Syntax: font:<fontname> 362 363Specify the font to use in text modes. Currently you can choose only 364between `VGA8x8`, `VGA8x16` and `PEARL8x8`. `VGA8x8` is default, if the 365vertical size of the display is less than 400 pixel rows. Otherwise, the 366`VGA8x16` font is the default. 367 3684.1.4) `hwscroll_` 369------------------ 370 371:Syntax: `hwscroll_<n>` 372 373The number of additional lines of video memory to reserve for 374speeding up the scrolling ("hardware scrolling"). Hardware scrolling 375is possible only if the kernel can set the video base address in steps 376fine enough. This is true for STE, MegaSTE, TT, and Falcon. It is not 377possible with plain STs and graphics cards (The former because the 378base address must be on a 256 byte boundary there, the latter because 379the kernel doesn't know how to set the base address at all.) 380 381By default, <n> is set to the number of visible text lines on the 382display. Thus, the amount of video memory is doubled, compared to no 383hardware scrolling. You can turn off the hardware scrolling altogether 384by setting <n> to 0. 385 3864.1.5) internal: 387---------------- 388 389:Syntax: internal:<xres>;<yres>[;<xres_max>;<yres_max>;<offset>] 390 391This option specifies the capabilities of some extended internal video 392hardware, like e.g. OverScan. <xres> and <yres> give the (extended) 393dimensions of the screen. 394 395If your OverScan needs a black border, you have to write the last 396three arguments of the "internal:". <xres_max> is the maximum line 397length the hardware allows, <yres_max> the maximum number of lines. 398<offset> is the offset of the visible part of the screen memory to its 399physical start, in bytes. 400 401Often, extended interval video hardware has to be activated somehow. 402For this, see the "sw_*" options below. 403 4044.1.6) external: 405---------------- 406 407:Syntax: 408 external:<xres>;<yres>;<depth>;<org>;<scrmem>[;<scrlen>[;<vgabase> 409 [;<colw>[;<coltype>[;<xres_virtual>]]]]] 410 411.. I had to break this line... 412 413This is probably the most complicated parameter... It specifies that 414you have some external video hardware (a graphics board), and how to 415use it under Linux/m68k. The kernel cannot know more about the hardware 416than you tell it here! The kernel also is unable to set or change any 417video modes, since it doesn't know about any board internal. So, you 418have to switch to that video mode before you start Linux, and cannot 419switch to another mode once Linux has started. 420 421The first 3 parameters of this sub-option should be obvious: <xres>, 422<yres> and <depth> give the dimensions of the screen and the number of 423planes (depth). The depth is the logarithm to base 2 of the number 424of colors possible. (Or, the other way round: The number of colors is 4252^depth). 426 427You have to tell the kernel furthermore how the video memory is 428organized. This is done by a letter as <org> parameter: 429 430 'n': 431 "normal planes", i.e. one whole plane after another 432 'i': 433 "interleaved planes", i.e. 16 bit of the first plane, than 16 bit 434 of the next, and so on... This mode is used only with the 435 built-in Atari video modes, I think there is no card that 436 supports this mode. 437 'p': 438 "packed pixels", i.e. <depth> consecutive bits stand for all 439 planes of one pixel; this is the most common mode for 8 planes 440 (256 colors) on graphic cards 441 't': 442 "true color" (more or less packed pixels, but without a color 443 lookup table); usually depth is 24 444 445For monochrome modes (i.e., <depth> is 1), the <org> letter has a 446different meaning: 447 448 'n': 449 normal colors, i.e. 0=white, 1=black 450 'i': 451 inverted colors, i.e. 0=black, 1=white 452 453The next important information about the video hardware is the base 454address of the video memory. That is given in the <scrmem> parameter, 455as a hexadecimal number with a "0x" prefix. You have to find out this 456address in the documentation of your hardware. 457 458The next parameter, <scrlen>, tells the kernel about the size of the 459video memory. If it's missing, the size is calculated from <xres>, 460<yres>, and <depth>. For now, it is not useful to write a value here. 461It would be used only for hardware scrolling (which isn't possible 462with the external driver, because the kernel cannot set the video base 463address), or for virtual resolutions under X (which the X server 464doesn't support yet). So, it's currently best to leave this field 465empty, either by ending the "external:" after the video address or by 466writing two consecutive semicolons, if you want to give a <vgabase> 467(it is allowed to leave this parameter empty). 468 469The <vgabase> parameter is optional. If it is not given, the kernel 470cannot read or write any color registers of the video hardware, and 471thus you have to set appropriate colors before you start Linux. But if 472your card is somehow VGA compatible, you can tell the kernel the base 473address of the VGA register set, so it can change the color lookup 474table. You have to look up this address in your board's documentation. 475To avoid misunderstandings: <vgabase> is the _base_ address, i.e. a 4k 476aligned address. For read/writing the color registers, the kernel 477uses the addresses vgabase+0x3c7...vgabase+0x3c9. The <vgabase> 478parameter is written in hexadecimal with a "0x" prefix, just as 479<scrmem>. 480 481<colw> is meaningful only if <vgabase> is specified. It tells the 482kernel how wide each of the color register is, i.e. the number of bits 483per single color (red/green/blue). Default is 6, another quite usual 484value is 8. 485 486Also <coltype> is used together with <vgabase>. It tells the kernel 487about the color register model of your gfx board. Currently, the types 488"vga" (which is also the default) and "mv300" (SANG MV300) are 489implemented. 490 491Parameter <xres_virtual> is required for ProMST or ET4000 cards where 492the physical linelength differs from the visible length. With ProMST, 493xres_virtual must be set to 2048. For ET4000, xres_virtual depends on the 494initialisation of the video-card. 495If you're missing a corresponding yres_virtual: the external part is legacy, 496therefore we don't support hardware-dependent functions like hardware-scroll, 497panning or blanking. 498 4994.1.7) eclock: 500-------------- 501 502The external pixel clock attached to the Falcon VIDEL shifter. This 503currently works only with the ScreenWonder! 504 5054.1.8) monitorcap: 506------------------- 507 508:Syntax: monitorcap:<vmin>;<vmax>;<hmin>;<hmax> 509 510This describes the capabilities of a multisync monitor. Don't use it 511with a fixed-frequency monitor! For now, only the Falcon frame buffer 512uses the settings of "monitorcap:". 513 514<vmin> and <vmax> are the minimum and maximum, resp., vertical frequencies 515your monitor can work with, in Hz. <hmin> and <hmax> are the same for 516the horizontal frequency, in kHz. 517 518 The defaults are 58;62;31;32 (VGA compatible). 519 520 The defaults for TV/SC1224/SC1435 cover both PAL and NTSC standards. 521 5224.1.9) keep 523------------ 524 525If this option is given, the framebuffer device doesn't do any video 526mode calculations and settings on its own. The only Atari fb device 527that does this currently is the Falcon. 528 529What you reach with this: Settings for unknown video extensions 530aren't overridden by the driver, so you can still use the mode found 531when booting, when the driver doesn't know to set this mode itself. 532But this also means, that you can't switch video modes anymore... 533 534An example where you may want to use "keep" is the ScreenBlaster for 535the Falcon. 536 537 5384.2) atamouse= 539-------------- 540 541:Syntax: atamouse=<x-threshold>,[<y-threshold>] 542 543With this option, you can set the mouse movement reporting threshold. 544This is the number of pixels of mouse movement that have to accumulate 545before the IKBD sends a new mouse packet to the kernel. Higher values 546reduce the mouse interrupt load and thus reduce the chance of keyboard 547overruns. Lower values give a slightly faster mouse responses and 548slightly better mouse tracking. 549 550You can set the threshold in x and y separately, but usually this is 551of little practical use. If there's just one number in the option, it 552is used for both dimensions. The default value is 2 for both 553thresholds. 554 555 5564.3) ataflop= 557------------- 558 559:Syntax: ataflop=<drive type>[,<trackbuffering>[,<steprateA>[,<steprateB>]]] 560 561 The drive type may be 0, 1, or 2, for DD, HD, and ED, resp. This 562 setting affects how many buffers are reserved and which formats are 563 probed (see also below). The default is 1 (HD). Only one drive type 564 can be selected. If you have two disk drives, select the "better" 565 type. 566 567 The second parameter <trackbuffer> tells the kernel whether to use 568 track buffering (1) or not (0). The default is machine-dependent: 569 no for the Medusa and yes for all others. 570 571 With the two following parameters, you can change the default 572 steprate used for drive A and B, resp. 573 574 5754.4) atascsi= 576------------- 577 578:Syntax: atascsi=<can_queue>[,<cmd_per_lun>[,<scat-gat>[,<host-id>[,<tagged>]]]] 579 580This option sets some parameters for the Atari native SCSI driver. 581Generally, any number of arguments can be omitted from the end. And 582for each of the numbers, a negative value means "use default". The 583defaults depend on whether TT-style or Falcon-style SCSI is used. 584Below, defaults are noted as n/m, where the first value refers to 585TT-SCSI and the latter to Falcon-SCSI. If an illegal value is given 586for one parameter, an error message is printed and that one setting is 587ignored (others aren't affected). 588 589 <can_queue>: 590 This is the maximum number of SCSI commands queued internally to the 591 Atari SCSI driver. A value of 1 effectively turns off the driver 592 internal multitasking (if it causes problems). Legal values are >= 593 1. <can_queue> can be as high as you like, but values greater than 594 <cmd_per_lun> times the number of SCSI targets (LUNs) you have 595 don't make sense. Default: 16/8. 596 597 <cmd_per_lun>: 598 Maximum number of SCSI commands issued to the driver for one 599 logical unit (LUN, usually one SCSI target). Legal values start 600 from 1. If tagged queuing (see below) is not used, values greater 601 than 2 don't make sense, but waste memory. Otherwise, the maximum 602 is the number of command tags available to the driver (currently 603 32). Default: 8/1. (Note: Values > 1 seem to cause problems on a 604 Falcon, cause not yet known.) 605 606 The <cmd_per_lun> value at a great part determines the amount of 607 memory SCSI reserves for itself. The formula is rather 608 complicated, but I can give you some hints: 609 610 no scatter-gather: 611 cmd_per_lun * 232 bytes 612 full scatter-gather: 613 cmd_per_lun * approx. 17 Kbytes 614 615 <scat-gat>: 616 Size of the scatter-gather table, i.e. the number of requests 617 consecutive on the disk that can be merged into one SCSI command. 618 Legal values are between 0 and 255. Default: 255/0. Note: This 619 value is forced to 0 on a Falcon, since scatter-gather isn't 620 possible with the ST-DMA. Not using scatter-gather hurts 621 performance significantly. 622 623 <host-id>: 624 The SCSI ID to be used by the initiator (your Atari). This is 625 usually 7, the highest possible ID. Every ID on the SCSI bus must 626 be unique. Default: determined at run time: If the NV-RAM checksum 627 is valid, and bit 7 in byte 30 of the NV-RAM is set, the lower 3 628 bits of this byte are used as the host ID. (This method is defined 629 by Atari and also used by some TOS HD drivers.) If the above 630 isn't given, the default ID is 7. (both, TT and Falcon). 631 632 <tagged>: 633 0 means turn off tagged queuing support, all other values > 0 mean 634 use tagged queuing for targets that support it. Default: currently 635 off, but this may change when tagged queuing handling has been 636 proved to be reliable. 637 638 Tagged queuing means that more than one command can be issued to 639 one LUN, and the SCSI device itself orders the requests so they 640 can be performed in optimal order. Not all SCSI devices support 641 tagged queuing (:-(). 642 6434.5 switches= 644------------- 645 646:Syntax: switches=<list of switches> 647 648With this option you can switch some hardware lines that are often 649used to enable/disable certain hardware extensions. Examples are 650OverScan, overclocking, ... 651 652The <list of switches> is a comma-separated list of the following 653items: 654 655 ikbd: 656 set RTS of the keyboard ACIA high 657 midi: 658 set RTS of the MIDI ACIA high 659 snd6: 660 set bit 6 of the PSG port A 661 snd7: 662 set bit 6 of the PSG port A 663 664It doesn't make sense to mention a switch more than once (no 665difference to only once), but you can give as many switches as you 666want to enable different features. The switch lines are set as early 667as possible during kernel initialization (even before determining the 668present hardware.) 669 670All of the items can also be prefixed with `ov_`, i.e. `ov_ikbd`, 671`ov_midi`, ... These options are meant for switching on an OverScan 672video extension. The difference to the bare option is that the 673switch-on is done after video initialization, and somehow synchronized 674to the HBLANK. A speciality is that ov_ikbd and ov_midi are switched 675off before rebooting, so that OverScan is disabled and TOS boots 676correctly. 677 678If you give an option both, with and without the `ov_` prefix, the 679earlier initialization (`ov_`-less) takes precedence. But the 680switching-off on reset still happens in this case. 681 6825) Options for Amiga Only: 683========================== 684 6855.1) video= 686----------- 687 688:Syntax: video=<fbname>:<sub-options...> 689 690The <fbname> parameter specifies the name of the frame buffer, valid 691options are `amifb`, `cyber`, 'virge', `retz3` and `clgen`, provided 692that the respective frame buffer devices have been compiled into the 693kernel (or compiled as loadable modules). The behavior of the <fbname> 694option was changed in 2.1.57 so it is now recommended to specify this 695option. 696 697The <sub-options> is a comma-separated list of the sub-options listed 698below. This option is organized similar to the Atari version of the 699"video"-option (4.1), but knows fewer sub-options. 700 7015.1.1) video mode 702----------------- 703 704Again, similar to the video mode for the Atari (see 4.1.1). Predefined 705modes depend on the used frame buffer device. 706 707OCS, ECS and AGA machines all use the color frame buffer. The following 708predefined video modes are available: 709 710NTSC modes: 711 - ntsc : 640x200, 15 kHz, 60 Hz 712 - ntsc-lace : 640x400, 15 kHz, 60 Hz interlaced 713 714PAL modes: 715 - pal : 640x256, 15 kHz, 50 Hz 716 - pal-lace : 640x512, 15 kHz, 50 Hz interlaced 717 718ECS modes: 719 - multiscan : 640x480, 29 kHz, 57 Hz 720 - multiscan-lace : 640x960, 29 kHz, 57 Hz interlaced 721 - euro36 : 640x200, 15 kHz, 72 Hz 722 - euro36-lace : 640x400, 15 kHz, 72 Hz interlaced 723 - euro72 : 640x400, 29 kHz, 68 Hz 724 - euro72-lace : 640x800, 29 kHz, 68 Hz interlaced 725 - super72 : 800x300, 23 kHz, 70 Hz 726 - super72-lace : 800x600, 23 kHz, 70 Hz interlaced 727 - dblntsc-ff : 640x400, 27 kHz, 57 Hz 728 - dblntsc-lace : 640x800, 27 kHz, 57 Hz interlaced 729 - dblpal-ff : 640x512, 27 kHz, 47 Hz 730 - dblpal-lace : 640x1024, 27 kHz, 47 Hz interlaced 731 - dblntsc : 640x200, 27 kHz, 57 Hz doublescan 732 - dblpal : 640x256, 27 kHz, 47 Hz doublescan 733 734VGA modes: 735 - vga : 640x480, 31 kHz, 60 Hz 736 - vga70 : 640x400, 31 kHz, 70 Hz 737 738Please notice that the ECS and VGA modes require either an ECS or AGA 739chipset, and that these modes are limited to 2-bit color for the ECS 740chipset and 8-bit color for the AGA chipset. 741 7425.1.2) depth 743------------ 744 745:Syntax: depth:<nr. of bit-planes> 746 747Specify the number of bit-planes for the selected video-mode. 748 7495.1.3) inverse 750-------------- 751 752Use inverted display (black on white). Functionally the same as the 753"inverse" sub-option for the Atari. 754 7555.1.4) font 756----------- 757 758:Syntax: font:<fontname> 759 760Specify the font to use in text modes. Functionally the same as the 761"font" sub-option for the Atari, except that `PEARL8x8` is used instead 762of `VGA8x8` if the vertical size of the display is less than 400 pixel 763rows. 764 7655.1.5) monitorcap: 766------------------- 767 768:Syntax: monitorcap:<vmin>;<vmax>;<hmin>;<hmax> 769 770This describes the capabilities of a multisync monitor. For now, only 771the color frame buffer uses the settings of "monitorcap:". 772 773<vmin> and <vmax> are the minimum and maximum, resp., vertical frequencies 774your monitor can work with, in Hz. <hmin> and <hmax> are the same for 775the horizontal frequency, in kHz. 776 777The defaults are 50;90;15;38 (Generic Amiga multisync monitor). 778 779 7805.2) fd_def_df0= 781---------------- 782 783:Syntax: fd_def_df0=<value> 784 785Sets the df0 value for "silent" floppy drives. The value should be in 786hexadecimal with "0x" prefix. 787 788 7895.3) wd33c93= 790------------- 791 792:Syntax: wd33c93=<sub-options...> 793 794These options affect the A590/A2091, A3000 and GVP Series II SCSI 795controllers. 796 797The <sub-options> is a comma-separated list of the sub-options listed 798below. 799 8005.3.1) nosync 801------------- 802 803:Syntax: nosync:bitmask 804 805bitmask is a byte where the 1st 7 bits correspond with the 7 806possible SCSI devices. Set a bit to prevent sync negotiation on that 807device. To maintain backwards compatibility, a command-line such as 808"wd33c93=255" will be automatically translated to 809"wd33c93=nosync:0xff". The default is to disable sync negotiation for 810all devices, eg. nosync:0xff. 811 8125.3.2) period 813------------- 814 815:Syntax: period:ns 816 817`ns` is the minimum # of nanoseconds in a SCSI data transfer 818period. Default is 500; acceptable values are 250 - 1000. 819 8205.3.3) disconnect 821----------------- 822 823:Syntax: disconnect:x 824 825Specify x = 0 to never allow disconnects, 2 to always allow them. 826x = 1 does 'adaptive' disconnects, which is the default and generally 827the best choice. 828 8295.3.4) debug 830------------ 831 832:Syntax: debug:x 833 834If `DEBUGGING_ON` is defined, x is a bit mask that causes various 835types of debug output to printed - see the DB_xxx defines in 836wd33c93.h. 837 8385.3.5) clock 839------------ 840 841:Syntax: clock:x 842 843x = clock input in MHz for WD33c93 chip. Normal values would be from 8448 through 20. The default value depends on your hostadapter(s), 845default for the A3000 internal controller is 14, for the A2091 it's 8 846and for the GVP hostadapters it's either 8 or 14, depending on the 847hostadapter and the SCSI-clock jumper present on some GVP 848hostadapters. 849 8505.3.6) next 851----------- 852 853No argument. Used to separate blocks of keywords when there's more 854than one wd33c93-based host adapter in the system. 855 8565.3.7) nodma 857------------ 858 859:Syntax: nodma:x 860 861If x is 1 (or if the option is just written as "nodma"), the WD33c93 862controller will not use DMA (= direct memory access) to access the 863Amiga's memory. This is useful for some systems (like A3000's and 864A4000's with the A3640 accelerator, revision 3.0) that have problems 865using DMA to chip memory. The default is 0, i.e. to use DMA if 866possible. 867 868 8695.4) gvp11= 870----------- 871 872:Syntax: gvp11=<addr-mask> 873 874The earlier versions of the GVP driver did not handle DMA 875address-mask settings correctly which made it necessary for some 876people to use this option, in order to get their GVP controller 877running under Linux. These problems have hopefully been solved and the 878use of this option is now highly unrecommended! 879 880Incorrect use can lead to unpredictable behavior, so please only use 881this option if you *know* what you are doing and have a reason to do 882so. In any case if you experience problems and need to use this 883option, please inform us about it by mailing to the Linux/68k kernel 884mailing list. 885 886The address mask set by this option specifies which addresses are 887valid for DMA with the GVP Series II SCSI controller. An address is 888valid, if no bits are set except the bits that are set in the mask, 889too. 890 891Some versions of the GVP can only DMA into a 24 bit address range, 892some can address a 25 bit address range while others can use the whole 89332 bit address range for DMA. The correct setting depends on your 894controller and should be autodetected by the driver. An example is the 89524 bit region which is specified by a mask of 0x00fffffe. 896