Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/Documentation/floppy.txt
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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Tag kernel26-2.6.12-alx-r9
1 | This file describes the floppy driver. |
2 | |
3 | FAQ list: |
4 | ========= |
5 | |
6 | A FAQ list may be found in the fdutils package (see below), and also |
7 | at http://fdutils.linux.lu/FAQ.html |
8 | |
9 | |
10 | LILO configuration options (Thinkpad users, read this) |
11 | ====================================================== |
12 | |
13 | The floppy driver is configured using the 'floppy=' option in |
14 | lilo. This option can be typed at the boot prompt, or entered in the |
15 | lilo configuration file. |
16 | |
17 | Example: If your kernel is called linux-2.6.9, type the following line |
18 | at the lilo boot prompt (if you have a thinkpad): |
19 | |
20 | linux-2.6.9 floppy=thinkpad |
21 | |
22 | You may also enter the following line in /etc/lilo.conf, in the description |
23 | of linux-2.6.9: |
24 | |
25 | append = "floppy=thinkpad" |
26 | |
27 | Several floppy related options may be given, example: |
28 | |
29 | linux-2.6.9 floppy=daring floppy=two_fdc |
30 | append = "floppy=daring floppy=two_fdc" |
31 | |
32 | If you give options both in the lilo config file and on the boot |
33 | prompt, the option strings of both places are concatenated, the boot |
34 | prompt options coming last. That's why there are also options to |
35 | restore the default behavior. |
36 | |
37 | |
38 | Module configuration options |
39 | ============================ |
40 | |
41 | If you use the floppy driver as a module, use the following syntax: |
42 | modprobe floppy <options> |
43 | |
44 | Example: |
45 | modprobe floppy omnibook messages |
46 | |
47 | If you need certain options enabled every time you load the floppy driver, |
48 | you can put: |
49 | |
50 | options floppy omnibook messages |
51 | |
52 | in /etc/modprobe.conf. |
53 | |
54 | |
55 | The floppy driver related options are: |
56 | |
57 | floppy=asus_pci |
58 | Sets the bit mask to allow only units 0 and 1. (default) |
59 | |
60 | floppy=daring |
61 | Tells the floppy driver that you have a well behaved floppy controller. |
62 | This allows more efficient and smoother operation, but may fail on |
63 | certain controllers. This may speed up certain operations. |
64 | |
65 | floppy=0,daring |
66 | Tells the floppy driver that your floppy controller should be used |
67 | with caution. |
68 | |
69 | floppy=one_fdc |
70 | Tells the floppy driver that you have only one floppy controller. |
71 | (default) |
72 | |
73 | floppy=two_fdc |
74 | floppy=<address>,two_fdc |
75 | Tells the floppy driver that you have two floppy controllers. |
76 | The second floppy controller is assumed to be at <address>. |
77 | This option is not needed if the second controller is at address |
78 | 0x370, and if you use the 'cmos' option. |
79 | |
80 | floppy=thinkpad |
81 | Tells the floppy driver that you have a Thinkpad. Thinkpads use an |
82 | inverted convention for the disk change line. |
83 | |
84 | floppy=0,thinkpad |
85 | Tells the floppy driver that you don't have a Thinkpad. |
86 | |
87 | floppy=omnibook |
88 | floppy=nodma |
89 | Tells the floppy driver not to use Dma for data transfers. |
90 | This is needed on HP Omnibooks, which don't have a workable |
91 | DMA channel for the floppy driver. This option is also useful |
92 | if you frequently get "Unable to allocate DMA memory" messages. |
93 | Indeed, dma memory needs to be continuous in physical memory, |
94 | and is thus harder to find, whereas non-dma buffers may be |
95 | allocated in virtual memory. However, I advise against this if |
96 | you have an FDC without a FIFO (8272A or 82072). 82072A and |
97 | later are OK. You also need at least a 486 to use nodma. |
98 | If you use nodma mode, I suggest you also set the FIFO |
99 | threshold to 10 or lower, in order to limit the number of data |
100 | transfer interrupts. |
101 | |
102 | If you have a FIFO-able FDC, the floppy driver automatically |
103 | falls back on non DMA mode if no DMA-able memory can be found. |
104 | If you want to avoid this, explicitly ask for 'yesdma'. |
105 | |
106 | floppy=yesdma |
107 | Tells the floppy driver that a workable DMA channel is available. |
108 | (default) |
109 | |
110 | floppy=nofifo |
111 | Disables the FIFO entirely. This is needed if you get "Bus |
112 | master arbitration error" messages from your Ethernet card (or |
113 | from other devices) while accessing the floppy. |
114 | |
115 | floppy=usefifo |
116 | Enables the FIFO. (default) |
117 | |
118 | floppy=<threshold>,fifo_depth |
119 | Sets the FIFO threshold. This is mostly relevant in DMA |
120 | mode. If this is higher, the floppy driver tolerates more |
121 | interrupt latency, but it triggers more interrupts (i.e. it |
122 | imposes more load on the rest of the system). If this is |
123 | lower, the interrupt latency should be lower too (faster |
124 | processor). The benefit of a lower threshold is less |
125 | interrupts. |
126 | |
127 | To tune the fifo threshold, switch on over/underrun messages |
128 | using 'floppycontrol --messages'. Then access a floppy |
129 | disk. If you get a huge amount of "Over/Underrun - retrying" |
130 | messages, then the fifo threshold is too low. Try with a |
131 | higher value, until you only get an occasional Over/Underrun. |
132 | It is a good idea to compile the floppy driver as a module |
133 | when doing this tuning. Indeed, it allows to try different |
134 | fifo values without rebooting the machine for each test. Note |
135 | that you need to do 'floppycontrol --messages' every time you |
136 | re-insert the module. |
137 | |
138 | Usually, tuning the fifo threshold should not be needed, as |
139 | the default (0xa) is reasonable. |
140 | |
141 | floppy=<drive>,<type>,cmos |
142 | Sets the CMOS type of <drive> to <type>. This is mandatory if |
143 | you have more than two floppy drives (only two can be |
144 | described in the physical CMOS), or if your BIOS uses |
145 | non-standard CMOS types. The CMOS types are: |
146 | |
147 | 0 - Use the value of the physical CMOS |
148 | 1 - 5 1/4 DD |
149 | 2 - 5 1/4 HD |
150 | 3 - 3 1/2 DD |
151 | 4 - 3 1/2 HD |
152 | 5 - 3 1/2 ED |
153 | 6 - 3 1/2 ED |
154 | 16 - unknown or not installed |
155 | |
156 | (Note: there are two valid types for ED drives. This is because 5 was |
157 | initially chosen to represent floppy *tapes*, and 6 for ED drives. |
158 | AMI ignored this, and used 5 for ED drives. That's why the floppy |
159 | driver handles both.) |
160 | |
161 | floppy=unexpected_interrupts |
162 | Print a warning message when an unexpected interrupt is received. |
163 | (default) |
164 | |
165 | floppy=no_unexpected_interrupts |
166 | floppy=L40SX |
167 | Don't print a message when an unexpected interrupt is received. This |
168 | is needed on IBM L40SX laptops in certain video modes. (There seems |
169 | to be an interaction between video and floppy. The unexpected |
170 | interrupts affect only performance, and can be safely ignored.) |
171 | |
172 | floppy=broken_dcl |
173 | Don't use the disk change line, but assume that the disk was |
174 | changed whenever the device node is reopened. Needed on some |
175 | boxes where the disk change line is broken or unsupported. |
176 | This should be regarded as a stopgap measure, indeed it makes |
177 | floppy operation less efficient due to unneeded cache |
178 | flushings, and slightly more unreliable. Please verify your |
179 | cable, connection and jumper settings if you have any DCL |
180 | problems. However, some older drives, and also some laptops |
181 | are known not to have a DCL. |
182 | |
183 | floppy=debug |
184 | Print debugging messages. |
185 | |
186 | floppy=messages |
187 | Print informational messages for some operations (disk change |
188 | notifications, warnings about over and underruns, and about |
189 | autodetection). |
190 | |
191 | floppy=silent_dcl_clear |
192 | Uses a less noisy way to clear the disk change line (which |
193 | doesn't involve seeks). Implied by 'daring' option. |
194 | |
195 | floppy=<nr>,irq |
196 | Sets the floppy IRQ to <nr> instead of 6. |
197 | |
198 | floppy=<nr>,dma |
199 | Sets the floppy DMA channel to <nr> instead of 2. |
200 | |
201 | floppy=slow |
202 | Use PS/2 stepping rate: |
203 | " PS/2 floppies have much slower step rates than regular floppies. |
204 | It's been recommended that take about 1/4 of the default speed |
205 | in some more extreme cases." |
206 | |
207 | |
208 | Supporting utilities and additional documentation: |
209 | ================================================== |
210 | |
211 | Additional parameters of the floppy driver can be configured at |
212 | runtime. Utilities which do this can be found in the fdutils package. |
213 | This package also contains a new version of mtools which allows to |
214 | access high capacity disks (up to 1992K on a high density 3 1/2 disk!). |
215 | It also contains additional documentation about the floppy driver. |
216 | |
217 | The latest version can be found at fdutils homepage: |
218 | http://fdutils.linux.lu |
219 | |
220 | The fdutils-5.4 release can be found at: |
221 | http://fdutils.linux.lu/fdutils-5.4.src.tar.gz |
222 | http://www.tux.org/pub/knaff/fdutils/fdutils-5.4.src.tar.gz |
223 | ftp://metalab.unc.edu/pub/Linux/utils/disk-management/fdutils-5.4.src.tar.gz |
224 | |
225 | Reporting problems about the floppy driver |
226 | ========================================== |
227 | |
228 | If you have a question or a bug report about the floppy driver, mail |
229 | me at Alain.Knaff@poboxes.com . If you post to Usenet, preferably use |
230 | comp.os.linux.hardware. As the volume in these groups is rather high, |
231 | be sure to include the word "floppy" (or "FLOPPY") in the subject |
232 | line. If the reported problem happens when mounting floppy disks, be |
233 | sure to mention also the type of the filesystem in the subject line. |
234 | |
235 | Be sure to read the FAQ before mailing/posting any bug reports! |
236 | |
237 | Alain |
238 | |
239 | Changelog |
240 | ========= |
241 | |
242 | 10-30-2004 : Cleanup, updating, add reference to module configuration. |
243 | James Nelson <james4765@gmail.com> |
244 | |
245 | 6-3-2000 : Original Document |