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Based on kernel version 3.16. Page generated on 2014-08-06 21:40 EST.

1	
2	
3					  Command Line Options for Linux/m68k
4					  ===================================
5	
6	Last Update: 2 May 1999
7	Linux/m68k version: 2.2.6
8	Author: Roman.Hodek@informatik.uni-erlangen.de (Roman Hodek)
9	Update: jds@kom.auc.dk (Jes Sorensen) and faq@linux-m68k.org (Chris Lawrence)
10	
11	0) Introduction
12	===============
13	
14	  Often I've been asked which command line options the Linux/m68k
15	kernel understands, or how the exact syntax for the ... option is, or
16	... about the option ... . I hope, this document supplies all the
17	answers...
18	
19	  Note that some options might be outdated, their descriptions being
20	incomplete or missing. Please update the information and send in the
21	patches.
22	
23	
24	1) Overview of the Kernel's Option Processing
25	=============================================
26	
27	The 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	
33	To which of these classes an argument belongs is determined as
34	follows: 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
36	is known to the kernel, it belongs to class 1. Otherwise, if the
37	argument contains an '=', it is of class 2, and the definition is put
38	into init's environment. All other arguments are passed to init as
39	command line options.
40	
41	  This document describes the valid kernel options for Linux/m68k in
42	the version mentioned at the start of this file. Later revisions may
43	add 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
46	list of values separated by commas. The interpretation of these values
47	is up to the driver that "owns" the option. This association of
48	options with drivers is also the reason that some are further
49	subdivided.
50	
51	
52	2) General Kernel Options
53	=========================
54	
55	2.1) root=
56	----------
57	
58	Syntax: root=/dev/<device>
59	    or: root=<hex_number>
60	
61	This tells the kernel which device it should mount as the root
62	filesystem. The device must be a block device with a valid filesystem
63	on it.
64	
65	  The first syntax gives the device by name. These names are converted
66	into a major/minor number internally in the kernel in an unusual way.
67	Normally, this "conversion" is done by the device files in /dev, but
68	this isn't possible here, because the root filesystem (with /dev)
69	isn't mounted yet... So the kernel parses the name itself, with some
70	hardcoded name to number mappings. The name must always be a
71	combination of two or three letters, followed by a decimal number.
72	Valid 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
85	partition number. Internally, the value of the number is just
86	added to the device number mentioned in the table above. The
87	exceptions are /dev/ram and /dev/fd, where /dev/ram refers to an
88	initial ramdisk loaded by your bootstrap program (please consult the
89	instructions for your bootstrap program to find out how to load an
90	initial 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
92	ramdisk. For the floppy devices, /dev/fd, the number stands for the
93	floppy 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
95	on. Since the number is just added, you can also force the disk format
96	by adding a number greater than 3. If you look into your /dev
97	directory, use can see the /dev/fd0D720 has major 2 and minor 16. You
98	can specify this device for the root FS by writing "root=/dev/fd16" on
99	the kernel command line.
100	
101	[Strange and maybe uninteresting stuff ON]
102	
103	  This unusual translation of device names has some strange
104	consequences: If, for example, you have a symbolic link from /dev/fd
105	to /dev/fd0D720 as an abbreviation for floppy driver #0 in DD format,
106	you cannot use this name for specifying the root device, because the
107	kernel cannot see this symlink before mounting the root FS and it
108	isn't in the table above. If you use it, the root device will not be 
109	set at all, without an error message. Another example: You cannot use a
110	partition on e.g. the sixth SCSI disk as the root filesystem, if you
111	want 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
113	use the sixth SCSI disk for the root FS, but you have to specify the
114	device by number... (see below). Or, even more strange, you can use the
115	fact that there is no range checking of the partition number, and your
116	knowledge 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
122	above, you can also specify it by major and minor numbers. These are
123	written in hex, with no prefix and no separator between. E.g., if you
124	have a CD with contents appropriate as a root filesystem in the first
125	SCSI CD-ROM drive, you boot from it by "root=0b00". Here, hex "0b" =
126	decimal 11 is the major of SCSI CD-ROMs, and the minor 0 stands for
127	the first of these. You can find out all valid major numbers by
128	looking into include/linux/major.h.
129	
130	In addition to major and minor numbers, if the device containing your
131	root partition uses a partition table format with unique partition
132	identifiers, then you may use them.  For instance,
133	"root=PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF".  It is also
134	possible to reference another partition on the same device using a
135	known partition UUID as the starting point.  For example,
136	if partition 5 of the device has the UUID of
137	00112233-4455-6677-8899-AABBCCDDEEFF then partition 3 may be found as
138	follows:
139	  PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF/PARTNROFF=-2
140	
141	Authoritative information can be found in
142	"Documentation/kernel-parameters.txt".
143	
144	
145	2.2) ro, rw
146	-----------
147	
148	Syntax: ro
149	    or: rw
150	
151	These two options tell the kernel whether it should mount the root
152	filesystem read-only or read-write. The default is read-only, except
153	for ramdisks, which default to read-write.
154	
155	
156	2.3) debug
157	----------
158	
159	Syntax: debug
160	
161	This raises the kernel log level to 10 (the default is 7). This is the
162	same level as set by the "dmesg" command, just that the maximum level
163	selectable by dmesg is 8.
164	
165	
166	2.4) debug=
167	-----------
168	
169	Syntax: debug=<device>
170	
171	This option causes certain kernel messages be printed to the selected
172	debugging device. This can aid debugging the kernel, since the
173	messages can be captured and analyzed on some other machine. Which
174	devices are possible depends on the machine type. There are no checks
175	for the validity of the device name. If the device isn't implemented,
176	nothing happens.
177	
178	  Messages logged this way are in general stack dumps after kernel
179	memory faults or bad kernel traps, and kernel panics. To be exact: all
180	messages of level 0 (panic messages) and all messages printed while
181	the log level is 8 or more (their level doesn't matter). Before stack
182	dumps, the kernel sets the log level to 10 automatically. A level of
183	at least 8 can also be set by the "debug" command line option (see
184	2.3) and at run time with "dmesg -n 8".
185	
186	Devices 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	
193	Devices 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	
207	2.6) ramdisk_size=
208	-------------
209	
210	Syntax: ramdisk_size=<size>
211	
212	  This option instructs the kernel to set up a ramdisk of the given
213	size in KBytes. Do not use this option if the ramdisk contents are
214	passed by bootstrap! In this case, the size is selected automatically
215	and should not be overwritten.
216	
217	  The only application is for root filesystems on floppy disks, that
218	should be loaded into memory. To do that, select the corresponding
219	size of the disk as ramdisk size, and set the root device to the disk
220	drive (with "root=").
221	
222	
223	2.7) swap=
224	2.8) buff=
225	-----------
226	
227	  I can't find any sign of these options in 2.2.6.
228	
229	
230	3) General Device Options (Amiga and Atari)
231	===========================================
232	
233	3.1) ether=
234	-----------
235	
236	Syntax: ether=[<irq>[,<base_addr>[,<mem_start>[,<mem_end>]]]],<dev-name>
237	
238	  <dev-name> is the name of a net driver, as specified in
239	drivers/net/Space.c in the Linux source. Most prominent are eth0, ...
240	eth3, sl0, ... sl3, ppp0, ..., ppp3, dummy, and lo.
241	
242	  The non-ethernet drivers (sl, ppp, dummy, lo) obviously ignore the
243	settings by this options. Also, the existing ethernet drivers for
244	Linux/m68k (ariadne, a2065, hydra) don't use them because Zorro boards
245	are really Plug-'n-Play, so the "ether=" option is useless altogether
246	for Linux/m68k.
247	
248	
249	3.2) hd=
250	--------
251	
252	Syntax: hd=<cylinders>,<heads>,<sectors>
253	
254	  This option sets the disk geometry of an IDE disk. The first hd=
255	option 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
257	to use this option, since the kernel can obtain the geometry data
258	itself. It exists just for the case that this fails for one of your
259	disks.
260	
261	
262	3.3) max_scsi_luns=
263	-------------------
264	
265	Syntax: max_scsi_luns=<n>
266	
267	  Sets the maximum number of LUNs (logical units) of SCSI devices to
268	be 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
270	configuration, else 1.
271	
272	
273	3.4) st=
274	--------
275	
276	Syntax: st=<buffer_size>,[<write_thres>,[<max_buffers>]]
277	
278	  Sets several parameters of the SCSI tape driver. <buffer_size> is
279	the number of 512-byte buffers reserved for tape operations for each
280	device. <write_thres> sets the number of blocks which must be filled
281	to start an actual write operation to the tape. Maximum value is the
282	total number of buffers. <max_buffer> limits the total number of
283	buffers allocated for all tape devices.
284	
285	
286	3.5) dmasound=
287	--------------
288	
289	Syntax: dmasound=[<buffers>,<buffer-size>[,<catch-radius>]]
290	
291	  This option controls some configurations of the Linux/m68k DMA sound
292	driver (Amiga and Atari): <buffers> is the number of buffers you want
293	to use (minimum 4, default 4), <buffer-size> is the size of each
294	buffer in kilobytes (minimum 4, default 32) and <catch-radius> says
295	how much percent of error will be tolerated when setting a frequency
296	(maximum 10, default 0). For example with 3% you can play 8000Hz
297	AU-Files on the Falcon with its hardware frequency of 8195Hz and thus
298	don't need to expand the sound.
299	
300	
301	
302	4) Options for Atari Only
303	=========================
304	
305	4.1) video=
306	-----------
307	
308	Syntax: video=<fbname>:<sub-options...>
309	
310	The <fbname> parameter specifies the name of the frame buffer,
311	eg. most atari users will want to specify `atafb' here. The
312	<sub-options> is a comma-separated list of the sub-options listed
313	below.
314	
315	NB: 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	
320	NBB: The behavior of video= was changed in 2.1.57 so the recommended
321	option is to specify the name of the frame buffer.
322	
323	4.1.1) Video Mode
324	-----------------
325	
326	This sub-option may be any of the predefined video modes, as listed
327	in atari/atafb.c in the Linux/m68k source tree. The kernel will
328	activate the given video mode at boot time and make it the default
329	mode, 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
345	modes names "default<n>" in turn, until one is possible with the
346	hardware in use.
347	
348	  A video mode setting doesn't make sense, if the external driver is
349	activated by a "external:" sub-option.
350	
351	4.1.2) inverse
352	--------------
353	
354	Invert the display. This affects both, text (consoles) and graphics
355	(X) display. Usually, the background is chosen to be black. With this
356	option, you can make the background white.
357	
358	4.1.3) font
359	-----------
360	
361	Syntax: font:<fontname>
362	
363	Specify the font to use in text modes. Currently you can choose only
364	between `VGA8x8', `VGA8x16' and `PEARL8x8'. `VGA8x8' is default, if the
365	vertical size of the display is less than 400 pixel rows. Otherwise, the
366	`VGA8x16' font is the default.
367	
368	4.1.4) hwscroll_
369	----------------
370	
371	Syntax: hwscroll_<n>
372	
373	The number of additional lines of video memory to reserve for
374	speeding up the scrolling ("hardware scrolling"). Hardware scrolling
375	is possible only if the kernel can set the video base address in steps
376	fine enough. This is true for STE, MegaSTE, TT, and Falcon. It is not
377	possible with plain STs and graphics cards (The former because the
378	base address must be on a 256 byte boundary there, the latter because
379	the 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
382	display. Thus, the amount of video memory is doubled, compared to no
383	hardware scrolling. You can turn off the hardware scrolling altogether
384	by setting <n> to 0.
385	
386	4.1.5) internal:
387	----------------
388	
389	Syntax: internal:<xres>;<yres>[;<xres_max>;<yres_max>;<offset>]
390	
391	This option specifies the capabilities of some extended internal video
392	hardware, like e.g. OverScan. <xres> and <yres> give the (extended)
393	dimensions of the screen.
394	
395	  If your OverScan needs a black border, you have to write the last
396	three arguments of the "internal:". <xres_max> is the maximum line
397	length 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
399	physical start, in bytes.
400	
401	  Often, extended interval video hardware has to be activated somehow.
402	For this, see the "sw_*" options below.
403	
404	4.1.6) external:
405	----------------
406	
407	Syntax:
408	  external:<xres>;<yres>;<depth>;<org>;<scrmem>[;<scrlen>[;<vgabase>\
409	           [;<colw>[;<coltype>[;<xres_virtual>]]]]]
410	
411	[I had to break this line...]
412	
413	  This is probably the most complicated parameter... It specifies that
414	you have some external video hardware (a graphics board), and how to
415	use it under Linux/m68k. The kernel cannot know more about the hardware
416	than you tell it here! The kernel also is unable to set or change any
417	video modes, since it doesn't know about any board internal. So, you
418	have to switch to that video mode before you start Linux, and cannot
419	switch 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
423	planes (depth). The depth is the logarithm to base 2 of the number
424	of colors possible. (Or, the other way round: The number of colors is
425	2^depth).
426	
427	  You have to tell the kernel furthermore how the video memory is
428	organized. 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	
441	For monochrome modes (i.e., <depth> is 1), the <org> letter has a
442	different 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
448	address of the video memory. That is given in the <scrmem> parameter,
449	as a hexadecimal number with a "0x" prefix. You have to find out this
450	address in the documentation of your hardware.
451	
452	  The next parameter, <scrlen>, tells the kernel about the size of the
453	video 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.
455	It would be used only for hardware scrolling (which isn't possible
456	with the external driver, because the kernel cannot set the video base
457	address), or for virtual resolutions under X (which the X server
458	doesn't support yet). So, it's currently best to leave this field
459	empty, either by ending the "external:" after the video address or by
460	writing 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
464	cannot read or write any color registers of the video hardware, and
465	thus you have to set appropriate colors before you start Linux. But if
466	your card is somehow VGA compatible, you can tell the kernel the base
467	address of the VGA register set, so it can change the color lookup
468	table. You have to look up this address in your board's documentation.
469	To avoid misunderstandings: <vgabase> is the _base_ address, i.e. a 4k
470	aligned address. For read/writing the color registers, the kernel
471	uses the addresses vgabase+0x3c7...vgabase+0x3c9. The <vgabase>
472	parameter 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
476	kernel how wide each of the color register is, i.e. the number of bits
477	per single color (red/green/blue). Default is 6, another quite usual
478	value is 8.
479	
480	  Also <coltype> is used together with <vgabase>. It tells the kernel
481	about the color register model of your gfx board. Currently, the types
482	"vga" (which is also the default) and "mv300" (SANG MV300) are
483	implemented.
484	
485	  Parameter <xres_virtual> is required for ProMST or ET4000 cards where
486	the physical linelength differs from the visible length. With ProMST, 
487	xres_virtual must be set to 2048. For ET4000, xres_virtual depends on the
488	initialisation of the video-card.
489	If you're missing a corresponding yres_virtual: the external part is legacy,
490	therefore we don't support hardware-dependent functions like hardware-scroll,
491	panning or blanking.
492	
493	4.1.7) eclock:
494	--------------
495	
496	The external pixel clock attached to the Falcon VIDEL shifter. This
497	currently works only with the ScreenWonder!
498	
499	4.1.8) monitorcap:
500	-------------------
501	
502	Syntax: monitorcap:<vmin>;<vmax>;<hmin>;<hmax>
503	
504	This describes the capabilities of a multisync monitor. Don't use it
505	with a fixed-frequency monitor! For now, only the Falcon frame buffer
506	uses the settings of "monitorcap:".
507	
508	  <vmin> and <vmax> are the minimum and maximum, resp., vertical frequencies
509	your monitor can work with, in Hz. <hmin> and <hmax> are the same for
510	the 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	
516	4.1.9) keep
517	------------
518	
519	If this option is given, the framebuffer device doesn't do any video
520	mode calculations and settings on its own. The only Atari fb device
521	that does this currently is the Falcon.
522	
523	  What you reach with this: Settings for unknown video extensions
524	aren't overridden by the driver, so you can still use the mode found
525	when booting, when the driver doesn't know to set this mode itself.
526	But 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
529	the Falcon.
530	
531	
532	4.2) atamouse=
533	--------------
534	
535	Syntax: atamouse=<x-threshold>,[<y-threshold>]
536	
537	  With this option, you can set the mouse movement reporting threshold.
538	This is the number of pixels of mouse movement that have to accumulate
539	before the IKBD sends a new mouse packet to the kernel. Higher values
540	reduce the mouse interrupt load and thus reduce the chance of keyboard
541	overruns. Lower values give a slightly faster mouse responses and
542	slightly better mouse tracking.
543	
544	  You can set the threshold in x and y separately, but usually this is
545	of little practical use. If there's just one number in the option, it
546	is used for both dimensions. The default value is 2 for both
547	thresholds.
548	
549	
550	4.3) ataflop=
551	-------------
552	
553	Syntax: 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	
569	4.4) atascsi=
570	-------------
571	
572	Syntax: atascsi=<can_queue>[,<cmd_per_lun>[,<scat-gat>[,<host-id>[,<tagged>]]]]
573	
574	  This option sets some parameters for the Atari native SCSI driver.
575	Generally, any number of arguments can be omitted from the end. And
576	for each of the numbers, a negative value means "use default". The
577	defaults depend on whether TT-style or Falcon-style SCSI is used.
578	Below, defaults are noted as n/m, where the first value refers to
579	TT-SCSI and the latter to Falcon-SCSI. If an illegal value is given
580	for one parameter, an error message is printed and that one setting is
581	ignored (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	
634	4.5 switches=
635	-------------
636	
637	Syntax: switches=<list of switches>
638	
639	  With this option you can switch some hardware lines that are often
640	used to enable/disable certain hardware extensions. Examples are
641	OverScan, overclocking, ...
642	
643	  The <list of switches> is a comma-separated list of the following
644	items:
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	
651	It doesn't make sense to mention a switch more than once (no
652	difference to only once), but you can give as many switches as you
653	want to enable different features. The switch lines are set as early
654	as possible during kernel initialization (even before determining the
655	present 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
659	video extension. The difference to the bare option is that the
660	switch-on is done after video initialization, and somehow synchronized
661	to the HBLANK. A speciality is that ov_ikbd and ov_midi are switched
662	off before rebooting, so that OverScan is disabled and TOS boots
663	correctly.
664	
665	  If you give an option both, with and without the "ov_" prefix, the
666	earlier initialization ("ov_"-less) takes precedence. But the
667	switching-off on reset still happens in this case.
668	
669	5) Options for Amiga Only:
670	==========================
671	
672	5.1) video=
673	-----------
674	
675	Syntax: video=<fbname>:<sub-options...>
676	
677	The <fbname> parameter specifies the name of the frame buffer, valid
678	options are `amifb', `cyber', 'virge', `retz3' and `clgen', provided
679	that the respective frame buffer devices have been compiled into the
680	kernel (or compiled as loadable modules). The behavior of the <fbname>
681	option was changed in 2.1.57 so it is now recommended to specify this
682	option.
683	
684	The <sub-options> is a comma-separated list of the sub-options listed
685	below. This option is organized similar to the Atari version of the
686	"video"-option (4.1), but knows fewer sub-options.
687	
688	5.1.1) video mode
689	-----------------
690	
691	Again, similar to the video mode for the Atari (see 4.1.1). Predefined
692	modes depend on the used frame buffer device.
693	
694	OCS, ECS and AGA machines all use the color frame buffer. The following
695	predefined video modes are available:
696	
697	NTSC modes:
698	 - ntsc            : 640x200, 15 kHz, 60 Hz
699	 - ntsc-lace       : 640x400, 15 kHz, 60 Hz interlaced
700	PAL modes:
701	 - pal             : 640x256, 15 kHz, 50 Hz
702	 - pal-lace        : 640x512, 15 kHz, 50 Hz interlaced
703	ECS 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
718	VGA modes:
719	 - vga             : 640x480, 31 kHz, 60 Hz
720	 - vga70           : 640x400, 31 kHz, 70 Hz
721	
722	Please notice that the ECS and VGA modes require either an ECS or AGA
723	chipset, and that these modes are limited to 2-bit color for the ECS
724	chipset and 8-bit color for the AGA chipset.
725	
726	5.1.2) depth
727	------------
728	
729	Syntax: depth:<nr. of bit-planes>
730	
731	Specify the number of bit-planes for the selected video-mode.
732	
733	5.1.3) inverse
734	--------------
735	
736	Use inverted display (black on white). Functionally the same as the
737	"inverse" sub-option for the Atari.
738	
739	5.1.4) font
740	-----------
741	
742	Syntax: font:<fontname>
743	
744	Specify 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
746	of `VGA8x8' if the vertical size of the display is less than 400 pixel
747	rows.
748	
749	5.1.5) monitorcap:
750	-------------------
751	
752	Syntax: monitorcap:<vmin>;<vmax>;<hmin>;<hmax>
753	
754	This describes the capabilities of a multisync monitor. For now, only
755	the color frame buffer uses the settings of "monitorcap:".
756	
757	  <vmin> and <vmax> are the minimum and maximum, resp., vertical frequencies
758	your monitor can work with, in Hz. <hmin> and <hmax> are the same for
759	the horizontal frequency, in kHz.
760	
761	  The defaults are 50;90;15;38 (Generic Amiga multisync monitor).
762	
763	
764	5.2) fd_def_df0=
765	----------------
766	
767	Syntax: fd_def_df0=<value>
768	
769	Sets the df0 value for "silent" floppy drives. The value should be in
770	hexadecimal with "0x" prefix.
771	
772	
773	5.3) wd33c93=
774	-------------
775	
776	Syntax: wd33c93=<sub-options...>
777	
778	These options affect the A590/A2091, A3000 and GVP Series II SCSI
779	controllers.
780	
781	The <sub-options> is a comma-separated list of the sub-options listed
782	below.
783	
784	5.3.1) nosync
785	-------------
786	
787	Syntax: nosync:bitmask
788	
789	  bitmask is a byte where the 1st 7 bits correspond with the 7
790	possible SCSI devices. Set a bit to prevent sync negotiation on that
791	device. 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
794	all devices, eg. nosync:0xff.
795	
796	5.3.2) period
797	-------------
798	
799	Syntax: period:ns
800	
801	  `ns' is the minimum # of nanoseconds in a SCSI data transfer
802	period. Default is 500; acceptable values are 250 - 1000.
803	
804	5.3.3) disconnect
805	-----------------
806	
807	Syntax: disconnect:x
808	
809	  Specify x = 0 to never allow disconnects, 2 to always allow them.
810	x = 1 does 'adaptive' disconnects, which is the default and generally
811	the best choice.
812	
813	5.3.4) debug
814	------------
815	
816	Syntax: debug:x
817	
818	  If `DEBUGGING_ON' is defined, x is a bit mask that causes various
819	types of debug output to printed - see the DB_xxx defines in
820	wd33c93.h.
821	
822	5.3.5) clock
823	------------
824	
825	Syntax: clock:x
826	
827	  x = clock input in MHz for WD33c93 chip. Normal values would be from
828	8 through 20. The default value depends on your hostadapter(s),
829	default for the A3000 internal controller is 14, for the A2091 it's 8
830	and for the GVP hostadapters it's either 8 or 14, depending on the
831	hostadapter and the SCSI-clock jumper present on some GVP
832	hostadapters.
833	
834	5.3.6) next
835	-----------
836	
837	  No argument. Used to separate blocks of keywords when there's more
838	than one wd33c93-based host adapter in the system.
839	
840	5.3.7) nodma
841	------------
842	
843	Syntax: nodma:x
844	
845	  If x is 1 (or if the option is just written as "nodma"), the WD33c93
846	controller will not use DMA (= direct memory access) to access the
847	Amiga's memory.  This is useful for some systems (like A3000's and
848	A4000's with the A3640 accelerator, revision 3.0) that have problems
849	using DMA to chip memory.  The default is 0, i.e. to use DMA if
850	possible.
851	
852	
853	5.4) gvp11=
854	-----------
855	
856	Syntax: gvp11=<addr-mask>
857	
858	  The earlier versions of the GVP driver did not handle DMA
859	address-mask settings correctly which made it necessary for some
860	people to use this option, in order to get their GVP controller
861	running under Linux. These problems have hopefully been solved and the
862	use of this option is now highly unrecommended!
863	
864	  Incorrect use can lead to unpredictable behavior, so please only use
865	this option if you *know* what you are doing and have a reason to do
866	so. In any case if you experience problems and need to use this
867	option, please inform us about it by mailing to the Linux/68k kernel
868	mailing list.
869	
870	  The address mask set by this option specifies which addresses are
871	valid for DMA with the GVP Series II SCSI controller. An address is
872	valid, if no bits are set except the bits that are set in the mask,
873	too.
874	
875	  Some versions of the GVP can only DMA into a 24 bit address range,
876	some can address a 25 bit address range while others can use the whole
877	32 bit address range for DMA. The correct setting depends on your
878	controller and should be autodetected by the driver. An example is the
879	24 bit region which is specified by a mask of 0x00fffffe.
880	
881	
882	/* Local Variables: */
883	/* mode: text       */
884	/* End:             */
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