1
2
3				  Command Line Options for Linux/m68k
4				  ===================================
5
6Last Update: 2 May 1999
7Linux/m68k version: 2.2.6
8Author: Roman.Hodek@informatik.uni-erlangen.de (Roman Hodek)
9Update: jds@kom.auc.dk (Jes Sorensen) and faq@linux-m68k.org (Chris Lawrence)
10
110) Introduction
12===============
13
14  Often I've been asked which command line options the Linux/m68k
15kernel understands, or how the exact syntax for the ... option is, or
16... about the option ... . I hope, this document supplies all the
17answers...
18
19  Note that some options might be outdated, their descriptions being
20incomplete or missing. Please update the information and send in the
21patches.
22
23
241) Overview of the Kernel's Option Processing
25=============================================
26
27The kernel knows three kinds of options on its command line:
28
29  1) kernel options
30  2) environment settings
31  3) arguments for init
32
33To which of these classes an argument belongs is determined as
34follows: If the option is known to the kernel itself, i.e. if the name
35(the part before the '=') or, in some cases, the whole argument string
36is known to the kernel, it belongs to class 1. Otherwise, if the
37argument contains an '=', it is of class 2, and the definition is put
38into init's environment. All other arguments are passed to init as
39command line options.
40
41  This document describes the valid kernel options for Linux/m68k in
42the version mentioned at the start of this file. Later revisions may
43add new such options, and some may be missing in older versions.
44
45  In general, the value (the part after the '=') of an option is a
46list of values separated by commas. The interpretation of these values
47is up to the driver that "owns" the option. This association of
48options with drivers is also the reason that some are further
49subdivided.
50
51
522) General Kernel Options
53=========================
54
552.1) root=
56----------
57
58Syntax: root=/dev/<device>
59    or: root=<hex_number>
60
61This tells the kernel which device it should mount as the root
62filesystem. The device must be a block device with a valid filesystem
63on it.
64
65  The first syntax gives the device by name. These names are converted
66into a major/minor number internally in the kernel in an unusual way.
67Normally, this "conversion" is done by the device files in /dev, but
68this isn't possible here, because the root filesystem (with /dev)
69isn't mounted yet... So the kernel parses the name itself, with some
70hardcoded name to number mappings. The name must always be a
71combination of two or three letters, followed by a decimal number.
72Valid names are:
73
74  /dev/ram: -> 0x0100 (initial ramdisk)
75  /dev/hda: -> 0x0300 (first IDE disk)
76  /dev/hdb: -> 0x0340 (second IDE disk)
77  /dev/sda: -> 0x0800 (first SCSI disk)
78  /dev/sdb: -> 0x0810 (second SCSI disk)
79  /dev/sdc: -> 0x0820 (third SCSI disk)
80  /dev/sdd: -> 0x0830 (forth SCSI disk)
81  /dev/sde: -> 0x0840 (fifth SCSI disk)
82  /dev/fd : -> 0x0200 (floppy disk)
83
84  The name must be followed by a decimal number, that stands for the
85partition number. Internally, the value of the number is just
86added to the device number mentioned in the table above. The
87exceptions are /dev/ram and /dev/fd, where /dev/ram refers to an
88initial ramdisk loaded by your bootstrap program (please consult the
89instructions for your bootstrap program to find out how to load an
90initial ramdisk). As of kernel version 2.0.18 you must specify
91/dev/ram as the root device if you want to boot from an initial
92ramdisk. For the floppy devices, /dev/fd, the number stands for the
93floppy drive number (there are no partitions on floppy disks). I.e.,
94/dev/fd0 stands for the first drive, /dev/fd1 for the second, and so
95on. Since the number is just added, you can also force the disk format
96by adding a number greater than 3. If you look into your /dev
97directory, use can see the /dev/fd0D720 has major 2 and minor 16. You
98can specify this device for the root FS by writing "root=/dev/fd16" on
99the kernel command line.
100
101[Strange and maybe uninteresting stuff ON]
102
103  This unusual translation of device names has some strange
104consequences: If, for example, you have a symbolic link from /dev/fd
105to /dev/fd0D720 as an abbreviation for floppy driver #0 in DD format,
106you cannot use this name for specifying the root device, because the
107kernel cannot see this symlink before mounting the root FS and it
108isn't in the table above. If you use it, the root device will not be 
109set at all, without an error message. Another example: You cannot use a
110partition on e.g. the sixth SCSI disk as the root filesystem, if you
111want to specify it by name. This is, because only the devices up to
112/dev/sde are in the table above, but not /dev/sdf. Although, you can
113use the sixth SCSI disk for the root FS, but you have to specify the
114device by number... (see below). Or, even more strange, you can use the
115fact that there is no range checking of the partition number, and your
116knowledge that each disk uses 16 minors, and write "root=/dev/sde17"
117(for /dev/sdf1).
118
119[Strange and maybe uninteresting stuff OFF]
120
121  If the device containing your root partition isn't in the table
122above, you can also specify it by major and minor numbers. These are
123written in hex, with no prefix and no separator between. E.g., if you
124have a CD with contents appropriate as a root filesystem in the first
125SCSI CD-ROM drive, you boot from it by "root=0b00". Here, hex "0b" =
126decimal 11 is the major of SCSI CD-ROMs, and the minor 0 stands for
127the first of these. You can find out all valid major numbers by
128looking into include/linux/major.h.
129
130In addition to major and minor numbers, if the device containing your
131root partition uses a partition table format with unique partition
132identifiers, then you may use them.  For instance,
133"root=PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF".  It is also
134possible to reference another partition on the same device using a
135known partition UUID as the starting point.  For example,
136if partition 5 of the device has the UUID of
13700112233-4455-6677-8899-AABBCCDDEEFF then partition 3 may be found as
138follows:
139  PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF/PARTNROFF=-2
140
141Authoritative information can be found in
142"Documentation/kernel-parameters.txt".
143
144
1452.2) ro, rw
146-----------
147
148Syntax: ro
149    or: rw
150
151These two options tell the kernel whether it should mount the root
152filesystem read-only or read-write. The default is read-only, except
153for ramdisks, which default to read-write.
154
155
1562.3) debug
157----------
158
159Syntax: debug
160
161This raises the kernel log level to 10 (the default is 7). This is the
162same level as set by the "dmesg" command, just that the maximum level
163selectable by dmesg is 8.
164
165
1662.4) debug=
167-----------
168
169Syntax: debug=<device>
170
171This option causes certain kernel messages be printed to the selected
172debugging device. This can aid debugging the kernel, since the
173messages can be captured and analyzed on some other machine. Which
174devices are possible depends on the machine type. There are no checks
175for the validity of the device name. If the device isn't implemented,
176nothing happens.
177
178  Messages logged this way are in general stack dumps after kernel
179memory faults or bad kernel traps, and kernel panics. To be exact: all
180messages of level 0 (panic messages) and all messages printed while
181the log level is 8 or more (their level doesn't matter). Before stack
182dumps, the kernel sets the log level to 10 automatically. A level of
183at least 8 can also be set by the "debug" command line option (see
1842.3) and at run time with "dmesg -n 8".
185
186Devices possible for Amiga:
187
188 - "ser": built-in serial port; parameters: 9600bps, 8N1
189 - "mem": Save the messages to a reserved area in chip mem. After
190          rebooting, they can be read under AmigaOS with the tool
191          'dmesg'.
192
193Devices possible for Atari:
194
195 - "ser1": ST-MFP serial port ("Modem1"); parameters: 9600bps, 8N1
196 - "ser2": SCC channel B serial port ("Modem2"); parameters: 9600bps, 8N1
197 - "ser" : default serial port
198           This is "ser2" for a Falcon, and "ser1" for any other machine
199 - "midi": The MIDI port; parameters: 31250bps, 8N1
200 - "par" : parallel port
201           The printing routine for this implements a timeout for the
202           case there's no printer connected (else the kernel would
203           lock up). The timeout is not exact, but usually a few
204           seconds.
205
206
2072.6) ramdisk_size=
208-------------
209
210Syntax: ramdisk_size=<size>
211
212  This option instructs the kernel to set up a ramdisk of the given
213size in KBytes. Do not use this option if the ramdisk contents are
214passed by bootstrap! In this case, the size is selected automatically
215and should not be overwritten.
216
217  The only application is for root filesystems on floppy disks, that
218should be loaded into memory. To do that, select the corresponding
219size of the disk as ramdisk size, and set the root device to the disk
220drive (with "root=").
221
222
2232.7) swap=
2242.8) buff=
225-----------
226
227  I can't find any sign of these options in 2.2.6.
228
229
2303) General Device Options (Amiga and Atari)
231===========================================
232
2333.1) ether=
234-----------
235
236Syntax: ether=[<irq>[,<base_addr>[,<mem_start>[,<mem_end>]]]],<dev-name>
237
238  <dev-name> is the name of a net driver, as specified in
239drivers/net/Space.c in the Linux source. Most prominent are eth0, ...
240eth3, sl0, ... sl3, ppp0, ..., ppp3, dummy, and lo.
241
242  The non-ethernet drivers (sl, ppp, dummy, lo) obviously ignore the
243settings by this options. Also, the existing ethernet drivers for
244Linux/m68k (ariadne, a2065, hydra) don't use them because Zorro boards
245are really Plug-'n-Play, so the "ether=" option is useless altogether
246for Linux/m68k.
247
248
2493.2) hd=
250--------
251
252Syntax: hd=<cylinders>,<heads>,<sectors>
253
254  This option sets the disk geometry of an IDE disk. The first hd=
255option is for the first IDE disk, the second for the second one.
256(I.e., you can give this option twice.) In most cases, you won't have
257to use this option, since the kernel can obtain the geometry data
258itself. It exists just for the case that this fails for one of your
259disks.
260
261
2623.3) max_scsi_luns=
263-------------------
264
265Syntax: max_scsi_luns=<n>
266
267  Sets the maximum number of LUNs (logical units) of SCSI devices to
268be scanned. Valid values for <n> are between 1 and 8. Default is 8 if
269"Probe all LUNs on each SCSI device" was selected during the kernel
270configuration, else 1.
271
272
2733.4) st=
274--------
275
276Syntax: st=<buffer_size>,[<write_thres>,[<max_buffers>]]
277
278  Sets several parameters of the SCSI tape driver. <buffer_size> is
279the number of 512-byte buffers reserved for tape operations for each
280device. <write_thres> sets the number of blocks which must be filled
281to start an actual write operation to the tape. Maximum value is the
282total number of buffers. <max_buffer> limits the total number of
283buffers allocated for all tape devices.
284
285
2863.5) dmasound=
287--------------
288
289Syntax: dmasound=[<buffers>,<buffer-size>[,<catch-radius>]]
290
291  This option controls some configurations of the Linux/m68k DMA sound
292driver (Amiga and Atari): <buffers> is the number of buffers you want
293to use (minimum 4, default 4), <buffer-size> is the size of each
294buffer in kilobytes (minimum 4, default 32) and <catch-radius> says
295how much percent of error will be tolerated when setting a frequency
296(maximum 10, default 0). For example with 3% you can play 8000Hz
297AU-Files on the Falcon with its hardware frequency of 8195Hz and thus
298don't need to expand the sound.
299
300
301
3024) Options for Atari Only
303=========================
304
3054.1) video=
306-----------
307
308Syntax: video=<fbname>:<sub-options...>
309
310The <fbname> parameter specifies the name of the frame buffer,
311eg. most atari users will want to specify `atafb' here. The
312<sub-options> is a comma-separated list of the sub-options listed
313below.
314
315NB: Please notice that this option was renamed from `atavideo' to
316    `video' during the development of the 1.3.x kernels, thus you
317    might need to update your boot-scripts if upgrading to 2.x from
318    an 1.2.x kernel.
319
320NBB: The behavior of video= was changed in 2.1.57 so the recommended
321option 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
344  If 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
348  A 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 both, text (consoles) and graphics
355(X) display. Usually, the background is chosen to be black. With this
356option, you can make the background white.
357
3584.1.3) font
359-----------
360
361Syntax: 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
371Syntax: 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
381  By 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
389Syntax: 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
395  If 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
401  Often, extended interval video hardware has to be activated somehow.
402For this, see the "sw_*" options below.
403
4044.1.6) external:
405----------------
406
407Syntax:
408  external:<xres>;<yres>;<depth>;<org>;<scrmem>[;<scrlen>[;<vgabase>\
409           [;<colw>[;<coltype>[;<xres_virtual>]]]]]
410
411[I had to break this line...]
412
413  This 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
421  The 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
427  You have to tell the kernel furthermore how the video memory is
428organized. This is done by a letter as <org> parameter:
429
430 'n': "normal planes", i.e. one whole plane after another
431 'i': "interleaved planes", i.e. 16 bit of the first plane, than 16 bit
432      of the next, and so on... This mode is used only with the
433	  built-in Atari video modes, I think there is no card that
434	  supports this mode.
435 'p': "packed pixels", i.e. <depth> consecutive bits stand for all
436	  planes of one pixel; this is the most common mode for 8 planes
437	  (256 colors) on graphic cards
438 't': "true color" (more or less packed pixels, but without a color
439	  lookup table); usually depth is 24
440
441For monochrome modes (i.e., <depth> is 1), the <org> letter has a
442different meaning:
443
444 'n': normal colors, i.e. 0=white, 1=black
445 'i': inverted colors, i.e. 0=black, 1=white
446
447  The next important information about the video hardware is the base
448address of the video memory. That is given in the <scrmem> parameter,
449as a hexadecimal number with a "0x" prefix. You have to find out this
450address in the documentation of your hardware.
451
452  The next parameter, <scrlen>, tells the kernel about the size of the
453video memory. If it's missing, the size is calculated from <xres>,
454<yres>, and <depth>. For now, it is not useful to write a value here.
455It would be used only for hardware scrolling (which isn't possible
456with the external driver, because the kernel cannot set the video base
457address), or for virtual resolutions under X (which the X server
458doesn't support yet). So, it's currently best to leave this field
459empty, either by ending the "external:" after the video address or by
460writing two consecutive semicolons, if you want to give a <vgabase>
461(it is allowed to leave this parameter empty).
462
463  The <vgabase> parameter is optional. If it is not given, the kernel
464cannot read or write any color registers of the video hardware, and
465thus you have to set appropriate colors before you start Linux. But if
466your card is somehow VGA compatible, you can tell the kernel the base
467address of the VGA register set, so it can change the color lookup
468table. You have to look up this address in your board's documentation.
469To avoid misunderstandings: <vgabase> is the _base_ address, i.e. a 4k
470aligned address. For read/writing the color registers, the kernel
471uses the addresses vgabase+0x3c7...vgabase+0x3c9. The <vgabase>
472parameter is written in hexadecimal with a "0x" prefix, just as
473<scrmem>.
474
475  <colw> is meaningful only if <vgabase> is specified. It tells the
476kernel how wide each of the color register is, i.e. the number of bits
477per single color (red/green/blue). Default is 6, another quite usual
478value is 8.
479
480  Also <coltype> is used together with <vgabase>. It tells the kernel
481about the color register model of your gfx board. Currently, the types
482"vga" (which is also the default) and "mv300" (SANG MV300) are
483implemented.
484
485  Parameter <xres_virtual> is required for ProMST or ET4000 cards where
486the physical linelength differs from the visible length. With ProMST, 
487xres_virtual must be set to 2048. For ET4000, xres_virtual depends on the
488initialisation of the video-card.
489If you're missing a corresponding yres_virtual: the external part is legacy,
490therefore we don't support hardware-dependent functions like hardware-scroll,
491panning or blanking.
492
4934.1.7) eclock:
494--------------
495
496The external pixel clock attached to the Falcon VIDEL shifter. This
497currently works only with the ScreenWonder!
498
4994.1.8) monitorcap:
500-------------------
501
502Syntax: monitorcap:<vmin>;<vmax>;<hmin>;<hmax>
503
504This describes the capabilities of a multisync monitor. Don't use it
505with a fixed-frequency monitor! For now, only the Falcon frame buffer
506uses the settings of "monitorcap:".
507
508  <vmin> and <vmax> are the minimum and maximum, resp., vertical frequencies
509your monitor can work with, in Hz. <hmin> and <hmax> are the same for
510the horizontal frequency, in kHz.
511
512  The defaults are 58;62;31;32 (VGA compatible).
513
514  The defaults for TV/SC1224/SC1435 cover both PAL and NTSC standards.
515
5164.1.9) keep
517------------
518
519If this option is given, the framebuffer device doesn't do any video
520mode calculations and settings on its own. The only Atari fb device
521that does this currently is the Falcon.
522
523  What you reach with this: Settings for unknown video extensions
524aren't overridden by the driver, so you can still use the mode found
525when booting, when the driver doesn't know to set this mode itself.
526But this also means, that you can't switch video modes anymore...
527
528  An example where you may want to use "keep" is the ScreenBlaster for
529the Falcon.
530
531
5324.2) atamouse=
533--------------
534
535Syntax: atamouse=<x-threshold>,[<y-threshold>]
536
537  With this option, you can set the mouse movement reporting threshold.
538This is the number of pixels of mouse movement that have to accumulate
539before the IKBD sends a new mouse packet to the kernel. Higher values
540reduce the mouse interrupt load and thus reduce the chance of keyboard
541overruns. Lower values give a slightly faster mouse responses and
542slightly better mouse tracking.
543
544  You can set the threshold in x and y separately, but usually this is
545of little practical use. If there's just one number in the option, it
546is used for both dimensions. The default value is 2 for both
547thresholds.
548
549
5504.3) ataflop=
551-------------
552
553Syntax: ataflop=<drive type>[,<trackbuffering>[,<steprateA>[,<steprateB>]]]
554
555   The drive type may be 0, 1, or 2, for DD, HD, and ED, resp. This
556   setting affects how many buffers are reserved and which formats are
557   probed (see also below). The default is 1 (HD). Only one drive type
558   can be selected. If you have two disk drives, select the "better"
559   type.
560
561   The second parameter <trackbuffer> tells the kernel whether to use
562   track buffering (1) or not (0). The default is machine-dependent:
563   no for the Medusa and yes for all others.
564
565   With the two following parameters, you can change the default
566   steprate used for drive A and B, resp. 
567
568
5694.4) atascsi=
570-------------
571
572Syntax: atascsi=<can_queue>[,<cmd_per_lun>[,<scat-gat>[,<host-id>[,<tagged>]]]]
573
574  This option sets some parameters for the Atari native SCSI driver.
575Generally, any number of arguments can be omitted from the end. And
576for each of the numbers, a negative value means "use default". The
577defaults depend on whether TT-style or Falcon-style SCSI is used.
578Below, defaults are noted as n/m, where the first value refers to
579TT-SCSI and the latter to Falcon-SCSI. If an illegal value is given
580for one parameter, an error message is printed and that one setting is
581ignored (others aren't affected).
582
583  <can_queue>:
584    This is the maximum number of SCSI commands queued internally to the
585    Atari SCSI driver. A value of 1 effectively turns off the driver
586    internal multitasking (if it causes problems). Legal values are >=
587    1. <can_queue> can be as high as you like, but values greater than
588    <cmd_per_lun> times the number of SCSI targets (LUNs) you have
589    don't make sense. Default: 16/8.
590
591  <cmd_per_lun>:
592    Maximum number of SCSI commands issued to the driver for one
593    logical unit (LUN, usually one SCSI target). Legal values start
594    from 1. If tagged queuing (see below) is not used, values greater
595    than 2 don't make sense, but waste memory. Otherwise, the maximum
596    is the number of command tags available to the driver (currently
597    32). Default: 8/1. (Note: Values > 1 seem to cause problems on a
598    Falcon, cause not yet known.)
599
600      The <cmd_per_lun> value at a great part determines the amount of
601    memory SCSI reserves for itself. The formula is rather
602    complicated, but I can give you some hints:
603      no scatter-gather  : cmd_per_lun * 232 bytes
604      full scatter-gather: cmd_per_lun * approx. 17 Kbytes
605
606  <scat-gat>:
607    Size of the scatter-gather table, i.e. the number of requests
608    consecutive on the disk that can be merged into one SCSI command.
609    Legal values are between 0 and 255. Default: 255/0. Note: This
610    value is forced to 0 on a Falcon, since scatter-gather isn't
611    possible with the ST-DMA. Not using scatter-gather hurts
612    performance significantly.
613
614  <host-id>:
615    The SCSI ID to be used by the initiator (your Atari). This is
616    usually 7, the highest possible ID. Every ID on the SCSI bus must
617    be unique. Default: determined at run time: If the NV-RAM checksum
618    is valid, and bit 7 in byte 30 of the NV-RAM is set, the lower 3
619    bits of this byte are used as the host ID. (This method is defined
620    by Atari and also used by some TOS HD drivers.) If the above
621    isn't given, the default ID is 7. (both, TT and Falcon).
622
623  <tagged>:
624    0 means turn off tagged queuing support, all other values > 0 mean
625    use tagged queuing for targets that support it. Default: currently
626    off, but this may change when tagged queuing handling has been
627    proved to be reliable.
628
629    Tagged queuing means that more than one command can be issued to
630    one LUN, and the SCSI device itself orders the requests so they
631    can be performed in optimal order. Not all SCSI devices support
632    tagged queuing (:-().
633
6344.5 switches=
635-------------
636
637Syntax: switches=<list of switches>
638
639  With this option you can switch some hardware lines that are often
640used to enable/disable certain hardware extensions. Examples are
641OverScan, overclocking, ...
642
643  The <list of switches> is a comma-separated list of the following
644items:
645
646  ikbd: set RTS of the keyboard ACIA high
647  midi: set RTS of the MIDI ACIA high
648  snd6: set bit 6 of the PSG port A
649  snd7: set bit 6 of the PSG port A
650
651It doesn't make sense to mention a switch more than once (no
652difference to only once), but you can give as many switches as you
653want to enable different features. The switch lines are set as early
654as possible during kernel initialization (even before determining the
655present hardware.)
656
657  All of the items can also be prefixed with "ov_", i.e. "ov_ikbd",
658"ov_midi", ... These options are meant for switching on an OverScan
659video extension. The difference to the bare option is that the
660switch-on is done after video initialization, and somehow synchronized
661to the HBLANK. A speciality is that ov_ikbd and ov_midi are switched
662off before rebooting, so that OverScan is disabled and TOS boots
663correctly.
664
665  If you give an option both, with and without the "ov_" prefix, the
666earlier initialization ("ov_"-less) takes precedence. But the
667switching-off on reset still happens in this case.
668
6695) Options for Amiga Only:
670==========================
671
6725.1) video=
673-----------
674
675Syntax: video=<fbname>:<sub-options...>
676
677The <fbname> parameter specifies the name of the frame buffer, valid
678options are `amifb', `cyber', 'virge', `retz3' and `clgen', provided
679that the respective frame buffer devices have been compiled into the
680kernel (or compiled as loadable modules). The behavior of the <fbname>
681option was changed in 2.1.57 so it is now recommended to specify this
682option.
683
684The <sub-options> is a comma-separated list of the sub-options listed
685below. This option is organized similar to the Atari version of the
686"video"-option (4.1), but knows fewer sub-options.
687
6885.1.1) video mode
689-----------------
690
691Again, similar to the video mode for the Atari (see 4.1.1). Predefined
692modes depend on the used frame buffer device.
693
694OCS, ECS and AGA machines all use the color frame buffer. The following
695predefined video modes are available:
696
697NTSC modes:
698 - ntsc            : 640x200, 15 kHz, 60 Hz
699 - ntsc-lace       : 640x400, 15 kHz, 60 Hz interlaced
700PAL modes:
701 - pal             : 640x256, 15 kHz, 50 Hz
702 - pal-lace        : 640x512, 15 kHz, 50 Hz interlaced
703ECS modes:
704 - multiscan       : 640x480, 29 kHz, 57 Hz
705 - multiscan-lace  : 640x960, 29 kHz, 57 Hz interlaced
706 - euro36          : 640x200, 15 kHz, 72 Hz
707 - euro36-lace     : 640x400, 15 kHz, 72 Hz interlaced
708 - euro72          : 640x400, 29 kHz, 68 Hz
709 - euro72-lace     : 640x800, 29 kHz, 68 Hz interlaced
710 - super72         : 800x300, 23 kHz, 70 Hz
711 - super72-lace    : 800x600, 23 kHz, 70 Hz interlaced
712 - dblntsc-ff      : 640x400, 27 kHz, 57 Hz
713 - dblntsc-lace    : 640x800, 27 kHz, 57 Hz interlaced
714 - dblpal-ff       : 640x512, 27 kHz, 47 Hz
715 - dblpal-lace     : 640x1024, 27 kHz, 47 Hz interlaced
716 - dblntsc         : 640x200, 27 kHz, 57 Hz doublescan
717 - dblpal          : 640x256, 27 kHz, 47 Hz doublescan
718VGA modes:
719 - vga             : 640x480, 31 kHz, 60 Hz
720 - vga70           : 640x400, 31 kHz, 70 Hz
721
722Please notice that the ECS and VGA modes require either an ECS or AGA
723chipset, and that these modes are limited to 2-bit color for the ECS
724chipset and 8-bit color for the AGA chipset.
725
7265.1.2) depth
727------------
728
729Syntax: depth:<nr. of bit-planes>
730
731Specify the number of bit-planes for the selected video-mode.
732
7335.1.3) inverse
734--------------
735
736Use inverted display (black on white). Functionally the same as the
737"inverse" sub-option for the Atari.
738
7395.1.4) font
740-----------
741
742Syntax: font:<fontname>
743
744Specify the font to use in text modes. Functionally the same as the
745"font" sub-option for the Atari, except that `PEARL8x8' is used instead
746of `VGA8x8' if the vertical size of the display is less than 400 pixel
747rows.
748
7495.1.5) monitorcap:
750-------------------
751
752Syntax: monitorcap:<vmin>;<vmax>;<hmin>;<hmax>
753
754This describes the capabilities of a multisync monitor. For now, only
755the color frame buffer uses the settings of "monitorcap:".
756
757  <vmin> and <vmax> are the minimum and maximum, resp., vertical frequencies
758your monitor can work with, in Hz. <hmin> and <hmax> are the same for
759the horizontal frequency, in kHz.
760
761  The defaults are 50;90;15;38 (Generic Amiga multisync monitor).
762
763
7645.2) fd_def_df0=
765----------------
766
767Syntax: fd_def_df0=<value>
768
769Sets the df0 value for "silent" floppy drives. The value should be in
770hexadecimal with "0x" prefix.
771
772
7735.3) wd33c93=
774-------------
775
776Syntax: wd33c93=<sub-options...>
777
778These options affect the A590/A2091, A3000 and GVP Series II SCSI
779controllers.
780
781The <sub-options> is a comma-separated list of the sub-options listed
782below.
783
7845.3.1) nosync
785-------------
786
787Syntax: nosync:bitmask
788
789  bitmask is a byte where the 1st 7 bits correspond with the 7
790possible SCSI devices. Set a bit to prevent sync negotiation on that
791device. To maintain backwards compatibility, a command-line such as
792"wd33c93=255" will be automatically translated to
793"wd33c93=nosync:0xff". The default is to disable sync negotiation for
794all devices, eg. nosync:0xff.
795
7965.3.2) period
797-------------
798
799Syntax: period:ns
800
801  `ns' is the minimum # of nanoseconds in a SCSI data transfer
802period. Default is 500; acceptable values are 250 - 1000.
803
8045.3.3) disconnect
805-----------------
806
807Syntax: disconnect:x
808
809  Specify x = 0 to never allow disconnects, 2 to always allow them.
810x = 1 does 'adaptive' disconnects, which is the default and generally
811the best choice.
812
8135.3.4) debug
814------------
815
816Syntax: debug:x
817
818  If `DEBUGGING_ON' is defined, x is a bit mask that causes various
819types of debug output to printed - see the DB_xxx defines in
820wd33c93.h.
821
8225.3.5) clock
823------------
824
825Syntax: clock:x
826
827  x = clock input in MHz for WD33c93 chip. Normal values would be from
8288 through 20. The default value depends on your hostadapter(s),
829default for the A3000 internal controller is 14, for the A2091 it's 8
830and for the GVP hostadapters it's either 8 or 14, depending on the
831hostadapter and the SCSI-clock jumper present on some GVP
832hostadapters.
833
8345.3.6) next
835-----------
836
837  No argument. Used to separate blocks of keywords when there's more
838than one wd33c93-based host adapter in the system.
839
8405.3.7) nodma
841------------
842
843Syntax: nodma:x
844
845  If x is 1 (or if the option is just written as "nodma"), the WD33c93
846controller will not use DMA (= direct memory access) to access the
847Amiga's memory.  This is useful for some systems (like A3000's and
848A4000's with the A3640 accelerator, revision 3.0) that have problems
849using DMA to chip memory.  The default is 0, i.e. to use DMA if
850possible.
851
852
8535.4) gvp11=
854-----------
855
856Syntax: gvp11=<addr-mask>
857
858  The earlier versions of the GVP driver did not handle DMA
859address-mask settings correctly which made it necessary for some
860people to use this option, in order to get their GVP controller
861running under Linux. These problems have hopefully been solved and the
862use of this option is now highly unrecommended!
863
864  Incorrect use can lead to unpredictable behavior, so please only use
865this option if you *know* what you are doing and have a reason to do
866so. In any case if you experience problems and need to use this
867option, please inform us about it by mailing to the Linux/68k kernel
868mailing list.
869
870  The address mask set by this option specifies which addresses are
871valid for DMA with the GVP Series II SCSI controller. An address is
872valid, if no bits are set except the bits that are set in the mask,
873too.
874
875  Some versions of the GVP can only DMA into a 24 bit address range,
876some can address a 25 bit address range while others can use the whole
87732 bit address range for DMA. The correct setting depends on your
878controller and should be autodetected by the driver. An example is the
87924 bit region which is specified by a mask of 0x00fffffe.
880
881
882/* Local Variables: */
883/* mode: text       */
884/* End:             */
885