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19  Note that some options might be outdated, their descriptions being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
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  PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF/PARTNROFF=-2
142
143Authoritative information can be found in
144"Documentation/kernel-parameters.txt".
145
146
1472.2) ro, rw
148-----------
149
150Syntax: ro
151    or: rw
152
153These two options tell the kernel whether it should mount the root
154filesystem read-only or read-write. The default is read-only, except
155for ramdisks, which default to read-write.
156
157
1582.3) debug
159----------
160
161Syntax: debug
162
163This raises the kernel log level to 10 (the default is 7). This is the
164same level as set by the "dmesg" command, just that the maximum level
165selectable by dmesg is 8.
166
167
1682.4) debug=
169-----------
170
171Syntax: debug=<device>
172
173This option causes certain kernel messages be printed to the selected
174debugging device. This can aid debugging the kernel, since the
175messages can be captured and analyzed on some other machine. Which
176devices are possible depends on the machine type. There are no checks
177for the validity of the device name. If the device isn't implemented,
178nothing happens.
179
180  Messages logged this way are in general stack dumps after kernel
181memory faults or bad kernel traps, and kernel panics. To be exact: all
182messages of level 0 (panic messages) and all messages printed while
183the log level is 8 or more (their level doesn't matter). Before stack
184dumps, the kernel sets the log level to 10 automatically. A level of
185at least 8 can also be set by the "debug" command line option (see
1862.3) and at run time with "dmesg -n 8".
187
188Devices possible for Amiga:
189
190 - "ser": built-in serial port; parameters: 9600bps, 8N1
191 - "mem": Save the messages to a reserved area in chip mem. After
192          rebooting, they can be read under AmigaOS with the tool
193          'dmesg'.
194
195Devices possible for Atari:
196
197 - "ser1": ST-MFP serial port ("Modem1"); parameters: 9600bps, 8N1
198 - "ser2": SCC channel B serial port ("Modem2"); parameters: 9600bps, 8N1
199 - "ser" : default serial port
200           This is "ser2" for a Falcon, and "ser1" for any other machine
201 - "midi": The MIDI port; parameters: 31250bps, 8N1
202 - "par" : parallel port
203           The printing routine for this implements a timeout for the
204           case there's no printer connected (else the kernel would
205           lock up). The timeout is not exact, but usually a few
206           seconds.
207
208
2092.6) ramdisk_size=
210-------------
211
212Syntax: ramdisk_size=<size>
213
214  This option instructs the kernel to set up a ramdisk of the given
215size in KBytes. Do not use this option if the ramdisk contents are
216passed by bootstrap! In this case, the size is selected automatically
217and should not be overwritten.
218
219  The only application is for root filesystems on floppy disks, that
220should be loaded into memory. To do that, select the corresponding
221size of the disk as ramdisk size, and set the root device to the disk
222drive (with "root=").
223
224
2252.7) swap=
2262.8) buff=
227-----------
228
229  I can't find any sign of these options in 2.2.6.
230
231
2323) General Device Options (Amiga and Atari)
233===========================================
234
2353.1) ether=
236-----------
237
238Syntax: ether=[<irq>[,<base_addr>[,<mem_start>[,<mem_end>]]]],<dev-name>
239
240  <dev-name> is the name of a net driver, as specified in
241drivers/net/Space.c in the Linux source. Most prominent are eth0, ...
242eth3, sl0, ... sl3, ppp0, ..., ppp3, dummy, and lo.
243
244  The non-ethernet drivers (sl, ppp, dummy, lo) obviously ignore the
245settings by this options. Also, the existing ethernet drivers for
246Linux/m68k (ariadne, a2065, hydra) don't use them because Zorro boards
247are really Plug-'n-Play, so the "ether=" option is useless altogether
248for Linux/m68k.
249
250
2513.2) hd=
252--------
253
254Syntax: hd=<cylinders>,<heads>,<sectors>
255
256  This option sets the disk geometry of an IDE disk. The first hd=
257option is for the first IDE disk, the second for the second one.
258(I.e., you can give this option twice.) In most cases, you won't have
259to use this option, since the kernel can obtain the geometry data
260itself. It exists just for the case that this fails for one of your
261disks.
262
263
2643.3) max_scsi_luns=
265-------------------
266
267Syntax: max_scsi_luns=<n>
268
269  Sets the maximum number of LUNs (logical units) of SCSI devices to
270be scanned. Valid values for <n> are between 1 and 8. Default is 8 if
271"Probe all LUNs on each SCSI device" was selected during the kernel
272configuration, else 1.
273
274
2753.4) st=
276--------
277
278Syntax: st=<buffer_size>,[<write_thres>,[<max_buffers>]]
279
280  Sets several parameters of the SCSI tape driver. <buffer_size> is
281the number of 512-byte buffers reserved for tape operations for each
282device. <write_thres> sets the number of blocks which must be filled
283to start an actual write operation to the tape. Maximum value is the
284total number of buffers. <max_buffer> limits the total number of
285buffers allocated for all tape devices.
286
287
2883.5) dmasound=
289--------------
290
291Syntax: dmasound=[<buffers>,<buffer-size>[,<catch-radius>]]
292
293  This option controls some configurations of the Linux/m68k DMA sound
294driver (Amiga and Atari): <buffers> is the number of buffers you want
295to use (minimum 4, default 4), <buffer-size> is the size of each
296buffer in kilobytes (minimum 4, default 32) and <catch-radius> says
297how much percent of error will be tolerated when setting a frequency
298(maximum 10, default 0). For example with 3% you can play 8000Hz
299AU-Files on the Falcon with its hardware frequency of 8195Hz and thus
300don't need to expand the sound.
301
302
303
3044) Options for Atari Only
305=========================
306
3074.1) video=
308-----------
309
310Syntax: video=<fbname>:<sub-options...>
311
312The <fbname> parameter specifies the name of the frame buffer,
313eg. most atari users will want to specify `atafb' here. The
314<sub-options> is a comma-separated list of the sub-options listed
315below.
316
317NB: Please notice that this option was renamed from `atavideo' to
318    `video' during the development of the 1.3.x kernels, thus you
319    might need to update your boot-scripts if upgrading to 2.x from
320    an 1.2.x kernel.
321
322NBB: The behavior of video= was changed in 2.1.57 so the recommended
323option is to specify the name of the frame buffer.
324
3254.1.1) Video Mode
326-----------------
327
328This sub-option may be any of the predefined video modes, as listed
329in atari/atafb.c in the Linux/m68k source tree. The kernel will
330activate the given video mode at boot time and make it the default
331mode, if the hardware allows. Currently defined names are:
332
333 - stlow : 320x200x4
334 - stmid, default5 : 640x200x2
335 - sthigh, default4: 640x400x1
336 - ttlow : 320x480x8, TT only
337 - ttmid, default1 : 640x480x4, TT only
338 - tthigh, default2: 1280x960x1, TT only
339 - vga2 : 640x480x1, Falcon only
340 - vga4 : 640x480x2, Falcon only
341 - vga16, default3 : 640x480x4, Falcon only
342 - vga256 : 640x480x8, Falcon only
343 - falh2 : 896x608x1, Falcon only
344 - falh16 : 896x608x4, Falcon only
345
346  If no video mode is given on the command line, the kernel tries the
347modes names "default<n>" in turn, until one is possible with the
348hardware in use.
349
350  A video mode setting doesn't make sense, if the external driver is
351activated by a "external:" sub-option.
352
3534.1.2) inverse
354--------------
355
356Invert the display. This affects both, text (consoles) and graphics
357(X) display. Usually, the background is chosen to be black. With this
358option, you can make the background white.
359
3604.1.3) font
361-----------
362
363Syntax: font:<fontname>
364
365Specify the font to use in text modes. Currently you can choose only
366between `VGA8x8', `VGA8x16' and `PEARL8x8'. `VGA8x8' is default, if the
367vertical size of the display is less than 400 pixel rows. Otherwise, the
368`VGA8x16' font is the default.
369
3704.1.4) hwscroll_
371----------------
372
373Syntax: hwscroll_<n>
374
375The number of additional lines of video memory to reserve for
376speeding up the scrolling ("hardware scrolling"). Hardware scrolling
377is possible only if the kernel can set the video base address in steps
378fine enough. This is true for STE, MegaSTE, TT, and Falcon. It is not
379possible with plain STs and graphics cards (The former because the
380base address must be on a 256 byte boundary there, the latter because
381the kernel doesn't know how to set the base address at all.)
382
383  By default, <n> is set to the number of visible text lines on the
384display. Thus, the amount of video memory is doubled, compared to no
385hardware scrolling. You can turn off the hardware scrolling altogether
386by setting <n> to 0.
387
3884.1.5) internal:
389----------------
390
391Syntax: internal:<xres>;<yres>[;<xres_max>;<yres_max>;<offset>]
392
393This option specifies the capabilities of some extended internal video
394hardware, like e.g. OverScan. <xres> and <yres> give the (extended)
395dimensions of the screen.
396
397  If your OverScan needs a black border, you have to write the last
398three arguments of the "internal:". <xres_max> is the maximum line
399length the hardware allows, <yres_max> the maximum number of lines.
400<offset> is the offset of the visible part of the screen memory to its
401physical start, in bytes.
402
403  Often, extended interval video hardware has to be activated somehow.
404For this, see the "sw_*" options below.
405
4064.1.6) external:
407----------------
408
409Syntax:
410  external:<xres>;<yres>;<depth>;<org>;<scrmem>[;<scrlen>[;<vgabase>\
411           [;<colw>[;<coltype>[;<xres_virtual>]]]]]
412
413[I had to break this line...]
414
415  This is probably the most complicated parameter... It specifies that
416you have some external video hardware (a graphics board), and how to
417use it under Linux/m68k. The kernel cannot know more about the hardware
418than you tell it here! The kernel also is unable to set or change any
419video modes, since it doesn't know about any board internal. So, you
420have to switch to that video mode before you start Linux, and cannot
421switch to another mode once Linux has started.
422
423  The first 3 parameters of this sub-option should be obvious: <xres>,
424<yres> and <depth> give the dimensions of the screen and the number of
425planes (depth). The depth is the logarithm to base 2 of the number
426of colors possible. (Or, the other way round: The number of colors is
4272^depth).
428
429  You have to tell the kernel furthermore how the video memory is
430organized. This is done by a letter as <org> parameter:
431
432 'n': "normal planes", i.e. one whole plane after another
433 'i': "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': "packed pixels", i.e. <depth> consecutive bits stand for all
438      planes of one pixel; this is the most common mode for 8 planes
439      (256 colors) on graphic cards
440 't': "true color" (more or less packed pixels, but without a color
441      lookup table); usually depth is 24
442
443For monochrome modes (i.e., <depth> is 1), the <org> letter has a
444different meaning:
445
446 'n': normal colors, i.e. 0=white, 1=black
447 'i': inverted colors, i.e. 0=black, 1=white
448
449  The next important information about the video hardware is the base
450address of the video memory. That is given in the <scrmem> parameter,
451as a hexadecimal number with a "0x" prefix. You have to find out this
452address in the documentation of your hardware.
453
454  The next parameter, <scrlen>, tells the kernel about the size of the
455video memory. If it's missing, the size is calculated from <xres>,
456<yres>, and <depth>. For now, it is not useful to write a value here.
457It would be used only for hardware scrolling (which isn't possible
458with the external driver, because the kernel cannot set the video base
459address), or for virtual resolutions under X (which the X server
460doesn't support yet). So, it's currently best to leave this field
461empty, either by ending the "external:" after the video address or by
462writing two consecutive semicolons, if you want to give a <vgabase>
463(it is allowed to leave this parameter empty).
464
465  The <vgabase> parameter is optional. If it is not given, the kernel
466cannot read or write any color registers of the video hardware, and
467thus you have to set appropriate colors before you start Linux. But if
468your card is somehow VGA compatible, you can tell the kernel the base
469address of the VGA register set, so it can change the color lookup
470table. You have to look up this address in your board's documentation.
471To avoid misunderstandings: <vgabase> is the _base_ address, i.e. a 4k
472aligned address. For read/writing the color registers, the kernel
473uses the addresses vgabase+0x3c7...vgabase+0x3c9. The <vgabase>
474parameter is written in hexadecimal with a "0x" prefix, just as
475<scrmem>.
476
477  <colw> is meaningful only if <vgabase> is specified. It tells the
478kernel how wide each of the color register is, i.e. the number of bits
479per single color (red/green/blue). Default is 6, another quite usual
480value is 8.
481
482  Also <coltype> is used together with <vgabase>. It tells the kernel
483about the color register model of your gfx board. Currently, the types
484"vga" (which is also the default) and "mv300" (SANG MV300) are
485implemented.
486
487  Parameter <xres_virtual> is required for ProMST or ET4000 cards where
488the physical linelength differs from the visible length. With ProMST,
489xres_virtual must be set to 2048. For ET4000, xres_virtual depends on the
490initialisation of the video-card.
491If you're missing a corresponding yres_virtual: the external part is legacy,
492therefore we don't support hardware-dependent functions like hardware-scroll,
493panning or blanking.
494
4954.1.7) eclock:
496--------------
497
498The external pixel clock attached to the Falcon VIDEL shifter. This
499currently works only with the ScreenWonder!
500
5014.1.8) monitorcap:
502-------------------
503
504Syntax: monitorcap:<vmin>;<vmax>;<hmin>;<hmax>
505
506This describes the capabilities of a multisync monitor. Don't use it
507with a fixed-frequency monitor! For now, only the Falcon frame buffer
508uses the settings of "monitorcap:".
509
510  <vmin> and <vmax> are the minimum and maximum, resp., vertical frequencies
511your monitor can work with, in Hz. <hmin> and <hmax> are the same for
512the horizontal frequency, in kHz.
513
514  The defaults are 58;62;31;32 (VGA compatible).
515
516  The defaults for TV/SC1224/SC1435 cover both PAL and NTSC standards.
517
5184.1.9) keep
519------------
520
521If this option is given, the framebuffer device doesn't do any video
522mode calculations and settings on its own. The only Atari fb device
523that does this currently is the Falcon.
524
525  What you reach with this: Settings for unknown video extensions
526aren't overridden by the driver, so you can still use the mode found
527when booting, when the driver doesn't know to set this mode itself.
528But this also means, that you can't switch video modes anymore...
529
530  An example where you may want to use "keep" is the ScreenBlaster for
531the Falcon.
532
533
5344.2) atamouse=
535--------------
536
537Syntax: atamouse=<x-threshold>,[<y-threshold>]
538
539  With this option, you can set the mouse movement reporting threshold.
540This is the number of pixels of mouse movement that have to accumulate
541before the IKBD sends a new mouse packet to the kernel. Higher values
542reduce the mouse interrupt load and thus reduce the chance of keyboard
543overruns. Lower values give a slightly faster mouse responses and
544slightly better mouse tracking.
545
546  You can set the threshold in x and y separately, but usually this is
547of little practical use. If there's just one number in the option, it
548is used for both dimensions. The default value is 2 for both
549thresholds.
550
551
5524.3) ataflop=
553-------------
554
555Syntax: ataflop=<drive type>[,<trackbuffering>[,<steprateA>[,<steprateB>]]]
556
557   The drive type may be 0, 1, or 2, for DD, HD, and ED, resp. This
558   setting affects how many buffers are reserved and which formats are
559   probed (see also below). The default is 1 (HD). Only one drive type
560   can be selected. If you have two disk drives, select the "better"
561   type.
562
563   The second parameter <trackbuffer> tells the kernel whether to use
564   track buffering (1) or not (0). The default is machine-dependent:
565   no for the Medusa and yes for all others.
566
567   With the two following parameters, you can change the default
568   steprate used for drive A and B, resp.
569
570
5714.4) atascsi=
572-------------
573
574Syntax: atascsi=<can_queue>[,<cmd_per_lun>[,<scat-gat>[,<host-id>[,<tagged>]]]]
575
576  This option sets some parameters for the Atari native SCSI driver.
577Generally, any number of arguments can be omitted from the end. And
578for each of the numbers, a negative value means "use default". The
579defaults depend on whether TT-style or Falcon-style SCSI is used.
580Below, defaults are noted as n/m, where the first value refers to
581TT-SCSI and the latter to Falcon-SCSI. If an illegal value is given
582for one parameter, an error message is printed and that one setting is
583ignored (others aren't affected).
584
585  <can_queue>:
586    This is the maximum number of SCSI commands queued internally to the
587    Atari SCSI driver. A value of 1 effectively turns off the driver
588    internal multitasking (if it causes problems). Legal values are >=
589    1. <can_queue> can be as high as you like, but values greater than
590    <cmd_per_lun> times the number of SCSI targets (LUNs) you have
591    don't make sense. Default: 16/8.
592
593  <cmd_per_lun>:
594    Maximum number of SCSI commands issued to the driver for one
595    logical unit (LUN, usually one SCSI target). Legal values start
596    from 1. If tagged queuing (see below) is not used, values greater
597    than 2 don't make sense, but waste memory. Otherwise, the maximum
598    is the number of command tags available to the driver (currently
599    32). Default: 8/1. (Note: Values > 1 seem to cause problems on a
600    Falcon, cause not yet known.)
601
602      The <cmd_per_lun> value at a great part determines the amount of
603    memory SCSI reserves for itself. The formula is rather
604    complicated, but I can give you some hints:
605      no scatter-gather : cmd_per_lun * 232 bytes
606      full scatter-gather: cmd_per_lun * approx. 17 Kbytes
607
608  <scat-gat>:
609    Size of the scatter-gather table, i.e. the number of requests
610    consecutive on the disk that can be merged into one SCSI command.
611    Legal values are between 0 and 255. Default: 255/0. Note: This
612    value is forced to 0 on a Falcon, since scatter-gather isn't
613    possible with the ST-DMA. Not using scatter-gather hurts
614    performance significantly.
615
616  <host-id>:
617    The SCSI ID to be used by the initiator (your Atari). This is
618    usually 7, the highest possible ID. Every ID on the SCSI bus must
619    be unique. Default: determined at run time: If the NV-RAM checksum
620    is valid, and bit 7 in byte 30 of the NV-RAM is set, the lower 3
621    bits of this byte are used as the host ID. (This method is defined
622    by Atari and also used by some TOS HD drivers.) If the above
623    isn't given, the default ID is 7. (both, TT and Falcon).
624
625  <tagged>:
626    0 means turn off tagged queuing support, all other values > 0 mean
627    use tagged queuing for targets that support it. Default: currently
628    off, but this may change when tagged queuing handling has been
629    proved to be reliable.
630
631    Tagged queuing means that more than one command can be issued to
632    one LUN, and the SCSI device itself orders the requests so they
633    can be performed in optimal order. Not all SCSI devices support
634    tagged queuing (:-().
635
6364.5 switches=
637-------------
638
639Syntax: switches=<list of switches>
640
641  With this option you can switch some hardware lines that are often
642used to enable/disable certain hardware extensions. Examples are
643OverScan, overclocking, ...
644
645  The <list of switches> is a comma-separated list of the following
646items:
647
648  ikbd: set RTS of the keyboard ACIA high
649  midi: set RTS of the MIDI ACIA high
650  snd6: set bit 6 of the PSG port A
651  snd7: set bit 6 of the PSG port A
652
653It doesn't make sense to mention a switch more than once (no
654difference to only once), but you can give as many switches as you
655want to enable different features. The switch lines are set as early
656as possible during kernel initialization (even before determining the
657present hardware.)
658
659  All of the items can also be prefixed with "ov_", i.e. "ov_ikbd",
660"ov_midi", ... These options are meant for switching on an OverScan
661video extension. The difference to the bare option is that the
662switch-on is done after video initialization, and somehow synchronized
663to the HBLANK. A speciality is that ov_ikbd and ov_midi are switched
664off before rebooting, so that OverScan is disabled and TOS boots
665correctly.
666
667  If you give an option both, with and without the "ov_" prefix, the
668earlier initialization ("ov_"-less) takes precedence. But the
669switching-off on reset still happens in this case.
670
6715) Options for Amiga Only:
672==========================
673
6745.1) video=
675-----------
676
677Syntax: video=<fbname>:<sub-options...>
678
679The <fbname> parameter specifies the name of the frame buffer, valid
680options are `amifb', `cyber', 'virge', `retz3' and `clgen', provided
681that the respective frame buffer devices have been compiled into the
682kernel (or compiled as loadable modules). The behavior of the <fbname>
683option was changed in 2.1.57 so it is now recommended to specify this
684option.
685
686The <sub-options> is a comma-separated list of the sub-options listed
687below. This option is organized similar to the Atari version of the
688"video"-option (4.1), but knows fewer sub-options.
689
6905.1.1) video mode
691-----------------
692
693Again, similar to the video mode for the Atari (see 4.1.1). Predefined
694modes depend on the used frame buffer device.
695
696OCS, ECS and AGA machines all use the color frame buffer. The following
697predefined video modes are available:
698
699NTSC modes:
700 - ntsc : 640x200, 15 kHz, 60 Hz
701 - ntsc-lace : 640x400, 15 kHz, 60 Hz interlaced
702PAL modes:
703 - pal : 640x256, 15 kHz, 50 Hz
704 - pal-lace : 640x512, 15 kHz, 50 Hz interlaced
705ECS modes:
706 - multiscan : 640x480, 29 kHz, 57 Hz
707 - multiscan-lace : 640x960, 29 kHz, 57 Hz interlaced
708 - euro36 : 640x200, 15 kHz, 72 Hz
709 - euro36-lace : 640x400, 15 kHz, 72 Hz interlaced
710 - euro72 : 640x400, 29 kHz, 68 Hz
711 - euro72-lace : 640x800, 29 kHz, 68 Hz interlaced
712 - super72 : 800x300, 23 kHz, 70 Hz
713 - super72-lace : 800x600, 23 kHz, 70 Hz interlaced
714 - dblntsc-ff : 640x400, 27 kHz, 57 Hz
715 - dblntsc-lace : 640x800, 27 kHz, 57 Hz interlaced
716 - dblpal-ff : 640x512, 27 kHz, 47 Hz
717 - dblpal-lace : 640x1024, 27 kHz, 47 Hz interlaced
718 - dblntsc : 640x200, 27 kHz, 57 Hz doublescan
719 - dblpal : 640x256, 27 kHz, 47 Hz doublescan
720VGA modes:
721 - vga : 640x480, 31 kHz, 60 Hz
722 - vga70 : 640x400, 31 kHz, 70 Hz
723
724Please notice that the ECS and VGA modes require either an ECS or AGA
725chipset, and that these modes are limited to 2-bit color for the ECS
726chipset and 8-bit color for the AGA chipset.
727
7285.1.2) depth
729------------
730
731Syntax: depth:<nr. of bit-planes>
732
733Specify the number of bit-planes for the selected video-mode.
734
7355.1.3) inverse
736--------------
737
738Use inverted display (black on white). Functionally the same as the
739"inverse" sub-option for the Atari.
740
7415.1.4) font
742-----------
743
744Syntax: font:<fontname>
745
746Specify the font to use in text modes. Functionally the same as the
747"font" sub-option for the Atari, except that `PEARL8x8' is used instead
748of `VGA8x8' if the vertical size of the display is less than 400 pixel
749rows.
750
7515.1.5) monitorcap:
752-------------------
753
754Syntax: monitorcap:<vmin>;<vmax>;<hmin>;<hmax>
755
756This describes the capabilities of a multisync monitor. For now, only
757the color frame buffer uses the settings of "monitorcap:".
758
759  <vmin> and <vmax> are the minimum and maximum, resp., vertical frequencies
760your monitor can work with, in Hz. <hmin> and <hmax> are the same for
761the horizontal frequency, in kHz.
762
763  The defaults are 50;90;15;38 (Generic Amiga multisync monitor).
764
765
7665.2) fd_def_df0=
767----------------
768
769Syntax: fd_def_df0=<value>
770
771Sets the df0 value for "silent" floppy drives. The value should be in
772hexadecimal with "0x" prefix.
773
774
7755.3) wd33c93=
776-------------
777
778Syntax: wd33c93=<sub-options...>
779
780These options affect the A590/A2091, A3000 and GVP Series II SCSI
781controllers.
782
783The <sub-options> is a comma-separated list of the sub-options listed
784below.
785
7865.3.1) nosync
787-------------
788
789Syntax: nosync:bitmask
790
791  bitmask is a byte where the 1st 7 bits correspond with the 7
792possible SCSI devices. Set a bit to prevent sync negotiation on that
793device. To maintain backwards compatibility, a command-line such as
794"wd33c93=255" will be automatically translated to
795"wd33c93=nosync:0xff". The default is to disable sync negotiation for
796all devices, eg. nosync:0xff.
797
7985.3.2) period
799-------------
800
801Syntax: period:ns
802
803  `ns' is the minimum # of nanoseconds in a SCSI data transfer
804period. Default is 500; acceptable values are 250 - 1000.
805
8065.3.3) disconnect
807-----------------
808
809Syntax: disconnect:x
810
811  Specify x = 0 to never allow disconnects, 2 to always allow them.
812x = 1 does 'adaptive' disconnects, which is the default and generally
813the best choice.
814
8155.3.4) debug
816------------
817
818Syntax: debug:x
819
820  If `DEBUGGING_ON' is defined, x is a bit mask that causes various
821types of debug output to printed - see the DB_xxx defines in
822wd33c93.h.
823
8245.3.5) clock
825------------
826
827Syntax: clock:x
828
829  x = clock input in MHz for WD33c93 chip. Normal values would be from
8308 through 20. The default value depends on your hostadapter(s),
831default for the A3000 internal controller is 14, for the A2091 it's 8
832and for the GVP hostadapters it's either 8 or 14, depending on the
833hostadapter and the SCSI-clock jumper present on some GVP
834hostadapters.
835
8365.3.6) next
837-----------
838
839  No argument. Used to separate blocks of keywords when there's more
840than one wd33c93-based host adapter in the system.
841
8425.3.7) nodma
843------------
844
845Syntax: nodma:x
846
847  If x is 1 (or if the option is just written as "nodma"), the WD33c93
848controller will not use DMA (= direct memory access) to access the
849Amiga's memory. This is useful for some systems (like A3000's and
850A4000's with the A3640 accelerator, revision 3.0) that have problems
851using DMA to chip memory. The default is 0, i.e. to use DMA if
852possible.
853
854
8555.4) gvp11=
856-----------
857
858Syntax: gvp11=<addr-mask>
859
860  The earlier versions of the GVP driver did not handle DMA
861address-mask settings correctly which made it necessary for some
862people to use this option, in order to get their GVP controller
863running under Linux. These problems have hopefully been solved and the
864use of this option is now highly unrecommended!
865
866  Incorrect use can lead to unpredictable behavior, so please only use
867this option if you *know* what you are doing and have a reason to do
868so. In any case if you experience problems and need to use this
869option, please inform us about it by mailing to the Linux/68k kernel
870mailing list.
871
872  The address mask set by this option specifies which addresses are
873valid for DMA with the GVP Series II SCSI controller. An address is
874valid, if no bits are set except the bits that are set in the mask,
875too.
876
877  Some versions of the GVP can only DMA into a 24 bit address range,
878some can address a 25 bit address range while others can use the whole
87932 bit address range for DMA. The correct setting depends on your
880controller and should be autodetected by the driver. An example is the
88124 bit region which is specified by a mask of 0x00fffffe.
882
883
884/* Local Variables: */
885/* mode: text */
886/* End: */
887

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