Root/Documentation/m68k/kernel-options.txt

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19  Note that some options might be outdated, their descriptions being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  /dev/xda: -> 0x0c00 (first XT disk, unused in Linux/m68k)
84  /dev/xdb: -> 0x0c40 (second XT disk, unused in Linux/m68k)
85
86  The 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
105  This 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
123  If 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
132
1332.2) ro, rw
134-----------
135
136Syntax: ro
137    or: rw
138
139These two options tell the kernel whether it should mount the root
140filesystem read-only or read-write. The default is read-only, except
141for ramdisks, which default to read-write.
142
143
1442.3) debug
145----------
146
147Syntax: debug
148
149This raises the kernel log level to 10 (the default is 7). This is the
150same level as set by the "dmesg" command, just that the maximum level
151selectable by dmesg is 8.
152
153
1542.4) debug=
155-----------
156
157Syntax: debug=<device>
158
159This option causes certain kernel messages be printed to the selected
160debugging device. This can aid debugging the kernel, since the
161messages can be captured and analyzed on some other machine. Which
162devices are possible depends on the machine type. There are no checks
163for the validity of the device name. If the device isn't implemented,
164nothing happens.
165
166  Messages logged this way are in general stack dumps after kernel
167memory faults or bad kernel traps, and kernel panics. To be exact: all
168messages of level 0 (panic messages) and all messages printed while
169the log level is 8 or more (their level doesn't matter). Before stack
170dumps, the kernel sets the log level to 10 automatically. A level of
171at least 8 can also be set by the "debug" command line option (see
1722.3) and at run time with "dmesg -n 8".
173
174Devices possible for Amiga:
175
176 - "ser": built-in serial port; parameters: 9600bps, 8N1
177 - "mem": Save the messages to a reserved area in chip mem. After
178          rebooting, they can be read under AmigaOS with the tool
179          'dmesg'.
180
181Devices possible for Atari:
182
183 - "ser1": ST-MFP serial port ("Modem1"); parameters: 9600bps, 8N1
184 - "ser2": SCC channel B serial port ("Modem2"); parameters: 9600bps, 8N1
185 - "ser" : default serial port
186           This is "ser2" for a Falcon, and "ser1" for any other machine
187 - "midi": The MIDI port; parameters: 31250bps, 8N1
188 - "par" : parallel port
189           The printing routine for this implements a timeout for the
190           case there's no printer connected (else the kernel would
191           lock up). The timeout is not exact, but usually a few
192           seconds.
193
194
1952.6) ramdisk_size=
196-------------
197
198Syntax: ramdisk_size=<size>
199
200  This option instructs the kernel to set up a ramdisk of the given
201size in KBytes. Do not use this option if the ramdisk contents are
202passed by bootstrap! In this case, the size is selected automatically
203and should not be overwritten.
204
205  The only application is for root filesystems on floppy disks, that
206should be loaded into memory. To do that, select the corresponding
207size of the disk as ramdisk size, and set the root device to the disk
208drive (with "root=").
209
210
2112.7) swap=
2122.8) buff=
213-----------
214
215  I can't find any sign of these options in 2.2.6.
216
217
2183) General Device Options (Amiga and Atari)
219===========================================
220
2213.1) ether=
222-----------
223
224Syntax: ether=[<irq>[,<base_addr>[,<mem_start>[,<mem_end>]]]],<dev-name>
225
226  <dev-name> is the name of a net driver, as specified in
227drivers/net/Space.c in the Linux source. Most prominent are eth0, ...
228eth3, sl0, ... sl3, ppp0, ..., ppp3, dummy, and lo.
229
230  The non-ethernet drivers (sl, ppp, dummy, lo) obviously ignore the
231settings by this options. Also, the existing ethernet drivers for
232Linux/m68k (ariadne, a2065, hydra) don't use them because Zorro boards
233are really Plug-'n-Play, so the "ether=" option is useless altogether
234for Linux/m68k.
235
236
2373.2) hd=
238--------
239
240Syntax: hd=<cylinders>,<heads>,<sectors>
241
242  This option sets the disk geometry of an IDE disk. The first hd=
243option is for the first IDE disk, the second for the second one.
244(I.e., you can give this option twice.) In most cases, you won't have
245to use this option, since the kernel can obtain the geometry data
246itself. It exists just for the case that this fails for one of your
247disks.
248
249
2503.3) max_scsi_luns=
251-------------------
252
253Syntax: max_scsi_luns=<n>
254
255  Sets the maximum number of LUNs (logical units) of SCSI devices to
256be scanned. Valid values for <n> are between 1 and 8. Default is 8 if
257"Probe all LUNs on each SCSI device" was selected during the kernel
258configuration, else 1.
259
260
2613.4) st=
262--------
263
264Syntax: st=<buffer_size>,[<write_thres>,[<max_buffers>]]
265
266  Sets several parameters of the SCSI tape driver. <buffer_size> is
267the number of 512-byte buffers reserved for tape operations for each
268device. <write_thres> sets the number of blocks which must be filled
269to start an actual write operation to the tape. Maximum value is the
270total number of buffers. <max_buffer> limits the total number of
271buffers allocated for all tape devices.
272
273
2743.5) dmasound=
275--------------
276
277Syntax: dmasound=[<buffers>,<buffer-size>[,<catch-radius>]]
278
279  This option controls some configurations of the Linux/m68k DMA sound
280driver (Amiga and Atari): <buffers> is the number of buffers you want
281to use (minimum 4, default 4), <buffer-size> is the size of each
282buffer in kilobytes (minimum 4, default 32) and <catch-radius> says
283how much percent of error will be tolerated when setting a frequency
284(maximum 10, default 0). For example with 3% you can play 8000Hz
285AU-Files on the Falcon with its hardware frequency of 8195Hz and thus
286don't need to expand the sound.
287
288
289
2904) Options for Atari Only
291=========================
292
2934.1) video=
294-----------
295
296Syntax: video=<fbname>:<sub-options...>
297
298The <fbname> parameter specifies the name of the frame buffer,
299eg. most atari users will want to specify `atafb' here. The
300<sub-options> is a comma-separated list of the sub-options listed
301below.
302
303NB: Please notice that this option was renamed from `atavideo' to
304    `video' during the development of the 1.3.x kernels, thus you
305    might need to update your boot-scripts if upgrading to 2.x from
306    an 1.2.x kernel.
307
308NBB: The behavior of video= was changed in 2.1.57 so the recommended
309option is to specify the name of the frame buffer.
310
3114.1.1) Video Mode
312-----------------
313
314This sub-option may be any of the predefined video modes, as listed
315in atari/atafb.c in the Linux/m68k source tree. The kernel will
316activate the given video mode at boot time and make it the default
317mode, if the hardware allows. Currently defined names are:
318
319 - stlow : 320x200x4
320 - stmid, default5 : 640x200x2
321 - sthigh, default4: 640x400x1
322 - ttlow : 320x480x8, TT only
323 - ttmid, default1 : 640x480x4, TT only
324 - tthigh, default2: 1280x960x1, TT only
325 - vga2 : 640x480x1, Falcon only
326 - vga4 : 640x480x2, Falcon only
327 - vga16, default3 : 640x480x4, Falcon only
328 - vga256 : 640x480x8, Falcon only
329 - falh2 : 896x608x1, Falcon only
330 - falh16 : 896x608x4, Falcon only
331
332  If no video mode is given on the command line, the kernel tries the
333modes names "default<n>" in turn, until one is possible with the
334hardware in use.
335
336  A video mode setting doesn't make sense, if the external driver is
337activated by a "external:" sub-option.
338
3394.1.2) inverse
340--------------
341
342Invert the display. This affects both, text (consoles) and graphics
343(X) display. Usually, the background is chosen to be black. With this
344option, you can make the background white.
345
3464.1.3) font
347-----------
348
349Syntax: font:<fontname>
350
351Specify the font to use in text modes. Currently you can choose only
352between `VGA8x8', `VGA8x16' and `PEARL8x8'. `VGA8x8' is default, if the
353vertical size of the display is less than 400 pixel rows. Otherwise, the
354`VGA8x16' font is the default.
355
3564.1.4) hwscroll_
357----------------
358
359Syntax: hwscroll_<n>
360
361The number of additional lines of video memory to reserve for
362speeding up the scrolling ("hardware scrolling"). Hardware scrolling
363is possible only if the kernel can set the video base address in steps
364fine enough. This is true for STE, MegaSTE, TT, and Falcon. It is not
365possible with plain STs and graphics cards (The former because the
366base address must be on a 256 byte boundary there, the latter because
367the kernel doesn't know how to set the base address at all.)
368
369  By default, <n> is set to the number of visible text lines on the
370display. Thus, the amount of video memory is doubled, compared to no
371hardware scrolling. You can turn off the hardware scrolling altogether
372by setting <n> to 0.
373
3744.1.5) internal:
375----------------
376
377Syntax: internal:<xres>;<yres>[;<xres_max>;<yres_max>;<offset>]
378
379This option specifies the capabilities of some extended internal video
380hardware, like e.g. OverScan. <xres> and <yres> give the (extended)
381dimensions of the screen.
382
383  If your OverScan needs a black border, you have to write the last
384three arguments of the "internal:". <xres_max> is the maximum line
385length the hardware allows, <yres_max> the maximum number of lines.
386<offset> is the offset of the visible part of the screen memory to its
387physical start, in bytes.
388
389  Often, extended interval video hardware has to be activated somehow.
390For this, see the "sw_*" options below.
391
3924.1.6) external:
393----------------
394
395Syntax:
396  external:<xres>;<yres>;<depth>;<org>;<scrmem>[;<scrlen>[;<vgabase>\
397           [;<colw>[;<coltype>[;<xres_virtual>]]]]]
398
399[I had to break this line...]
400
401  This is probably the most complicated parameter... It specifies that
402you have some external video hardware (a graphics board), and how to
403use it under Linux/m68k. The kernel cannot know more about the hardware
404than you tell it here! The kernel also is unable to set or change any
405video modes, since it doesn't know about any board internal. So, you
406have to switch to that video mode before you start Linux, and cannot
407switch to another mode once Linux has started.
408
409  The first 3 parameters of this sub-option should be obvious: <xres>,
410<yres> and <depth> give the dimensions of the screen and the number of
411planes (depth). The depth is the logarithm to base 2 of the number
412of colors possible. (Or, the other way round: The number of colors is
4132^depth).
414
415  You have to tell the kernel furthermore how the video memory is
416organized. This is done by a letter as <org> parameter:
417
418 'n': "normal planes", i.e. one whole plane after another
419 'i': "interleaved planes", i.e. 16 bit of the first plane, than 16 bit
420      of the next, and so on... This mode is used only with the
421      built-in Atari video modes, I think there is no card that
422      supports this mode.
423 'p': "packed pixels", i.e. <depth> consecutive bits stand for all
424      planes of one pixel; this is the most common mode for 8 planes
425      (256 colors) on graphic cards
426 't': "true color" (more or less packed pixels, but without a color
427      lookup table); usually depth is 24
428
429For monochrome modes (i.e., <depth> is 1), the <org> letter has a
430different meaning:
431
432 'n': normal colors, i.e. 0=white, 1=black
433 'i': inverted colors, i.e. 0=black, 1=white
434
435  The next important information about the video hardware is the base
436address of the video memory. That is given in the <scrmem> parameter,
437as a hexadecimal number with a "0x" prefix. You have to find out this
438address in the documentation of your hardware.
439
440  The next parameter, <scrlen>, tells the kernel about the size of the
441video memory. If it's missing, the size is calculated from <xres>,
442<yres>, and <depth>. For now, it is not useful to write a value here.
443It would be used only for hardware scrolling (which isn't possible
444with the external driver, because the kernel cannot set the video base
445address), or for virtual resolutions under X (which the X server
446doesn't support yet). So, it's currently best to leave this field
447empty, either by ending the "external:" after the video address or by
448writing two consecutive semicolons, if you want to give a <vgabase>
449(it is allowed to leave this parameter empty).
450
451  The <vgabase> parameter is optional. If it is not given, the kernel
452cannot read or write any color registers of the video hardware, and
453thus you have to set appropriate colors before you start Linux. But if
454your card is somehow VGA compatible, you can tell the kernel the base
455address of the VGA register set, so it can change the color lookup
456table. You have to look up this address in your board's documentation.
457To avoid misunderstandings: <vgabase> is the _base_ address, i.e. a 4k
458aligned address. For read/writing the color registers, the kernel
459uses the addresses vgabase+0x3c7...vgabase+0x3c9. The <vgabase>
460parameter is written in hexadecimal with a "0x" prefix, just as
461<scrmem>.
462
463  <colw> is meaningful only if <vgabase> is specified. It tells the
464kernel how wide each of the color register is, i.e. the number of bits
465per single color (red/green/blue). Default is 6, another quite usual
466value is 8.
467
468  Also <coltype> is used together with <vgabase>. It tells the kernel
469about the color register model of your gfx board. Currently, the types
470"vga" (which is also the default) and "mv300" (SANG MV300) are
471implemented.
472
473  Parameter <xres_virtual> is required for ProMST or ET4000 cards where
474the physical linelength differs from the visible length. With ProMST,
475xres_virtual must be set to 2048. For ET4000, xres_virtual depends on the
476initialisation of the video-card.
477If you're missing a corresponding yres_virtual: the external part is legacy,
478therefore we don't support hardware-dependent functions like hardware-scroll,
479panning or blanking.
480
4814.1.7) eclock:
482--------------
483
484The external pixel clock attached to the Falcon VIDEL shifter. This
485currently works only with the ScreenWonder!
486
4874.1.8) monitorcap:
488-------------------
489
490Syntax: monitorcap:<vmin>;<vmax>;<hmin>;<hmax>
491
492This describes the capabilities of a multisync monitor. Don't use it
493with a fixed-frequency monitor! For now, only the Falcon frame buffer
494uses the settings of "monitorcap:".
495
496  <vmin> and <vmax> are the minimum and maximum, resp., vertical frequencies
497your monitor can work with, in Hz. <hmin> and <hmax> are the same for
498the horizontal frequency, in kHz.
499
500  The defaults are 58;62;31;32 (VGA compatible).
501
502  The defaults for TV/SC1224/SC1435 cover both PAL and NTSC standards.
503
5044.1.9) keep
505------------
506
507If this option is given, the framebuffer device doesn't do any video
508mode calculations and settings on its own. The only Atari fb device
509that does this currently is the Falcon.
510
511  What you reach with this: Settings for unknown video extensions
512aren't overridden by the driver, so you can still use the mode found
513when booting, when the driver doesn't know to set this mode itself.
514But this also means, that you can't switch video modes anymore...
515
516  An example where you may want to use "keep" is the ScreenBlaster for
517the Falcon.
518
519
5204.2) atamouse=
521--------------
522
523Syntax: atamouse=<x-threshold>,[<y-threshold>]
524
525  With this option, you can set the mouse movement reporting threshold.
526This is the number of pixels of mouse movement that have to accumulate
527before the IKBD sends a new mouse packet to the kernel. Higher values
528reduce the mouse interrupt load and thus reduce the chance of keyboard
529overruns. Lower values give a slightly faster mouse responses and
530slightly better mouse tracking.
531
532  You can set the threshold in x and y separately, but usually this is
533of little practical use. If there's just one number in the option, it
534is used for both dimensions. The default value is 2 for both
535thresholds.
536
537
5384.3) ataflop=
539-------------
540
541Syntax: ataflop=<drive type>[,<trackbuffering>[,<steprateA>[,<steprateB>]]]
542
543   The drive type may be 0, 1, or 2, for DD, HD, and ED, resp. This
544   setting affects how many buffers are reserved and which formats are
545   probed (see also below). The default is 1 (HD). Only one drive type
546   can be selected. If you have two disk drives, select the "better"
547   type.
548
549   The second parameter <trackbuffer> tells the kernel whether to use
550   track buffering (1) or not (0). The default is machine-dependent:
551   no for the Medusa and yes for all others.
552
553   With the two following parameters, you can change the default
554   steprate used for drive A and B, resp.
555
556
5574.4) atascsi=
558-------------
559
560Syntax: atascsi=<can_queue>[,<cmd_per_lun>[,<scat-gat>[,<host-id>[,<tagged>]]]]
561
562  This option sets some parameters for the Atari native SCSI driver.
563Generally, any number of arguments can be omitted from the end. And
564for each of the numbers, a negative value means "use default". The
565defaults depend on whether TT-style or Falcon-style SCSI is used.
566Below, defaults are noted as n/m, where the first value refers to
567TT-SCSI and the latter to Falcon-SCSI. If an illegal value is given
568for one parameter, an error message is printed and that one setting is
569ignored (others aren't affected).
570
571  <can_queue>:
572    This is the maximum number of SCSI commands queued internally to the
573    Atari SCSI driver. A value of 1 effectively turns off the driver
574    internal multitasking (if it causes problems). Legal values are >=
575    1. <can_queue> can be as high as you like, but values greater than
576    <cmd_per_lun> times the number of SCSI targets (LUNs) you have
577    don't make sense. Default: 16/8.
578
579  <cmd_per_lun>:
580    Maximum number of SCSI commands issued to the driver for one
581    logical unit (LUN, usually one SCSI target). Legal values start
582    from 1. If tagged queuing (see below) is not used, values greater
583    than 2 don't make sense, but waste memory. Otherwise, the maximum
584    is the number of command tags available to the driver (currently
585    32). Default: 8/1. (Note: Values > 1 seem to cause problems on a
586    Falcon, cause not yet known.)
587
588      The <cmd_per_lun> value at a great part determines the amount of
589    memory SCSI reserves for itself. The formula is rather
590    complicated, but I can give you some hints:
591      no scatter-gather : cmd_per_lun * 232 bytes
592      full scatter-gather: cmd_per_lun * approx. 17 Kbytes
593
594  <scat-gat>:
595    Size of the scatter-gather table, i.e. the number of requests
596    consecutive on the disk that can be merged into one SCSI command.
597    Legal values are between 0 and 255. Default: 255/0. Note: This
598    value is forced to 0 on a Falcon, since scatter-gather isn't
599    possible with the ST-DMA. Not using scatter-gather hurts
600    performance significantly.
601
602  <host-id>:
603    The SCSI ID to be used by the initiator (your Atari). This is
604    usually 7, the highest possible ID. Every ID on the SCSI bus must
605    be unique. Default: determined at run time: If the NV-RAM checksum
606    is valid, and bit 7 in byte 30 of the NV-RAM is set, the lower 3
607    bits of this byte are used as the host ID. (This method is defined
608    by Atari and also used by some TOS HD drivers.) If the above
609    isn't given, the default ID is 7. (both, TT and Falcon).
610
611  <tagged>:
612    0 means turn off tagged queuing support, all other values > 0 mean
613    use tagged queuing for targets that support it. Default: currently
614    off, but this may change when tagged queuing handling has been
615    proved to be reliable.
616
617    Tagged queuing means that more than one command can be issued to
618    one LUN, and the SCSI device itself orders the requests so they
619    can be performed in optimal order. Not all SCSI devices support
620    tagged queuing (:-().
621
6224.5 switches=
623-------------
624
625Syntax: switches=<list of switches>
626
627  With this option you can switch some hardware lines that are often
628used to enable/disable certain hardware extensions. Examples are
629OverScan, overclocking, ...
630
631  The <list of switches> is a comma-separated list of the following
632items:
633
634  ikbd: set RTS of the keyboard ACIA high
635  midi: set RTS of the MIDI ACIA high
636  snd6: set bit 6 of the PSG port A
637  snd7: set bit 6 of the PSG port A
638
639It doesn't make sense to mention a switch more than once (no
640difference to only once), but you can give as many switches as you
641want to enable different features. The switch lines are set as early
642as possible during kernel initialization (even before determining the
643present hardware.)
644
645  All of the items can also be prefixed with "ov_", i.e. "ov_ikbd",
646"ov_midi", ... These options are meant for switching on an OverScan
647video extension. The difference to the bare option is that the
648switch-on is done after video initialization, and somehow synchronized
649to the HBLANK. A speciality is that ov_ikbd and ov_midi are switched
650off before rebooting, so that OverScan is disabled and TOS boots
651correctly.
652
653  If you give an option both, with and without the "ov_" prefix, the
654earlier initialization ("ov_"-less) takes precedence. But the
655switching-off on reset still happens in this case.
656
6575) Options for Amiga Only:
658==========================
659
6605.1) video=
661-----------
662
663Syntax: video=<fbname>:<sub-options...>
664
665The <fbname> parameter specifies the name of the frame buffer, valid
666options are `amifb', `cyber', 'virge', `retz3' and `clgen', provided
667that the respective frame buffer devices have been compiled into the
668kernel (or compiled as loadable modules). The behavior of the <fbname>
669option was changed in 2.1.57 so it is now recommended to specify this
670option.
671
672The <sub-options> is a comma-separated list of the sub-options listed
673below. This option is organized similar to the Atari version of the
674"video"-option (4.1), but knows fewer sub-options.
675
6765.1.1) video mode
677-----------------
678
679Again, similar to the video mode for the Atari (see 4.1.1). Predefined
680modes depend on the used frame buffer device.
681
682OCS, ECS and AGA machines all use the color frame buffer. The following
683predefined video modes are available:
684
685NTSC modes:
686 - ntsc : 640x200, 15 kHz, 60 Hz
687 - ntsc-lace : 640x400, 15 kHz, 60 Hz interlaced
688PAL modes:
689 - pal : 640x256, 15 kHz, 50 Hz
690 - pal-lace : 640x512, 15 kHz, 50 Hz interlaced
691ECS modes:
692 - multiscan : 640x480, 29 kHz, 57 Hz
693 - multiscan-lace : 640x960, 29 kHz, 57 Hz interlaced
694 - euro36 : 640x200, 15 kHz, 72 Hz
695 - euro36-lace : 640x400, 15 kHz, 72 Hz interlaced
696 - euro72 : 640x400, 29 kHz, 68 Hz
697 - euro72-lace : 640x800, 29 kHz, 68 Hz interlaced
698 - super72 : 800x300, 23 kHz, 70 Hz
699 - super72-lace : 800x600, 23 kHz, 70 Hz interlaced
700 - dblntsc-ff : 640x400, 27 kHz, 57 Hz
701 - dblntsc-lace : 640x800, 27 kHz, 57 Hz interlaced
702 - dblpal-ff : 640x512, 27 kHz, 47 Hz
703 - dblpal-lace : 640x1024, 27 kHz, 47 Hz interlaced
704 - dblntsc : 640x200, 27 kHz, 57 Hz doublescan
705 - dblpal : 640x256, 27 kHz, 47 Hz doublescan
706VGA modes:
707 - vga : 640x480, 31 kHz, 60 Hz
708 - vga70 : 640x400, 31 kHz, 70 Hz
709
710Please notice that the ECS and VGA modes require either an ECS or AGA
711chipset, and that these modes are limited to 2-bit color for the ECS
712chipset and 8-bit color for the AGA chipset.
713
7145.1.2) depth
715------------
716
717Syntax: depth:<nr. of bit-planes>
718
719Specify the number of bit-planes for the selected video-mode.
720
7215.1.3) inverse
722--------------
723
724Use inverted display (black on white). Functionally the same as the
725"inverse" sub-option for the Atari.
726
7275.1.4) font
728-----------
729
730Syntax: font:<fontname>
731
732Specify the font to use in text modes. Functionally the same as the
733"font" sub-option for the Atari, except that `PEARL8x8' is used instead
734of `VGA8x8' if the vertical size of the display is less than 400 pixel
735rows.
736
7375.1.5) monitorcap:
738-------------------
739
740Syntax: monitorcap:<vmin>;<vmax>;<hmin>;<hmax>
741
742This describes the capabilities of a multisync monitor. For now, only
743the color frame buffer uses the settings of "monitorcap:".
744
745  <vmin> and <vmax> are the minimum and maximum, resp., vertical frequencies
746your monitor can work with, in Hz. <hmin> and <hmax> are the same for
747the horizontal frequency, in kHz.
748
749  The defaults are 50;90;15;38 (Generic Amiga multisync monitor).
750
751
7525.2) fd_def_df0=
753----------------
754
755Syntax: fd_def_df0=<value>
756
757Sets the df0 value for "silent" floppy drives. The value should be in
758hexadecimal with "0x" prefix.
759
760
7615.3) wd33c93=
762-------------
763
764Syntax: wd33c93=<sub-options...>
765
766These options affect the A590/A2091, A3000 and GVP Series II SCSI
767controllers.
768
769The <sub-options> is a comma-separated list of the sub-options listed
770below.
771
7725.3.1) nosync
773-------------
774
775Syntax: nosync:bitmask
776
777  bitmask is a byte where the 1st 7 bits correspond with the 7
778possible SCSI devices. Set a bit to prevent sync negotiation on that
779device. To maintain backwards compatibility, a command-line such as
780"wd33c93=255" will be automatically translated to
781"wd33c93=nosync:0xff". The default is to disable sync negotiation for
782all devices, eg. nosync:0xff.
783
7845.3.2) period
785-------------
786
787Syntax: period:ns
788
789  `ns' is the minimum # of nanoseconds in a SCSI data transfer
790period. Default is 500; acceptable values are 250 - 1000.
791
7925.3.3) disconnect
793-----------------
794
795Syntax: disconnect:x
796
797  Specify x = 0 to never allow disconnects, 2 to always allow them.
798x = 1 does 'adaptive' disconnects, which is the default and generally
799the best choice.
800
8015.3.4) debug
802------------
803
804Syntax: debug:x
805
806  If `DEBUGGING_ON' is defined, x is a bit mask that causes various
807types of debug output to printed - see the DB_xxx defines in
808wd33c93.h.
809
8105.3.5) clock
811------------
812
813Syntax: clock:x
814
815  x = clock input in MHz for WD33c93 chip. Normal values would be from
8168 through 20. The default value depends on your hostadapter(s),
817default for the A3000 internal controller is 14, for the A2091 it's 8
818and for the GVP hostadapters it's either 8 or 14, depending on the
819hostadapter and the SCSI-clock jumper present on some GVP
820hostadapters.
821
8225.3.6) next
823-----------
824
825  No argument. Used to separate blocks of keywords when there's more
826than one wd33c93-based host adapter in the system.
827
8285.3.7) nodma
829------------
830
831Syntax: nodma:x
832
833  If x is 1 (or if the option is just written as "nodma"), the WD33c93
834controller will not use DMA (= direct memory access) to access the
835Amiga's memory. This is useful for some systems (like A3000's and
836A4000's with the A3640 accelerator, revision 3.0) that have problems
837using DMA to chip memory. The default is 0, i.e. to use DMA if
838possible.
839
840
8415.4) gvp11=
842-----------
843
844Syntax: gvp11=<addr-mask>
845
846  The earlier versions of the GVP driver did not handle DMA
847address-mask settings correctly which made it necessary for some
848people to use this option, in order to get their GVP controller
849running under Linux. These problems have hopefully been solved and the
850use of this option is now highly unrecommended!
851
852  Incorrect use can lead to unpredictable behavior, so please only use
853this option if you *know* what you are doing and have a reason to do
854so. In any case if you experience problems and need to use this
855option, please inform us about it by mailing to the Linux/68k kernel
856mailing list.
857
858  The address mask set by this option specifies which addresses are
859valid for DMA with the GVP Series II SCSI controller. An address is
860valid, if no bits are set except the bits that are set in the mask,
861too.
862
863  Some versions of the GVP can only DMA into a 24 bit address range,
864some can address a 25 bit address range while others can use the whole
86532 bit address range for DMA. The correct setting depends on your
866controller and should be autodetected by the driver. An example is the
86724 bit region which is specified by a mask of 0x00fffffe.
868
869
870/* Local Variables: */
871/* mode: text */
872/* End: */
873

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