diff options
author | Randy Dunlap <randy.dunlap@oracle.com> | 2008-07-26 20:54:22 -0400 |
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committer | Ingo Molnar <mingo@elte.hu> | 2008-07-28 08:46:49 -0400 |
commit | 7225e75144b9718cbbe1820d9c011c809d5773fd (patch) | |
tree | ca922d1fac696a4c41f94366d54846ac8849f49a /Documentation/mtrr.txt | |
parent | a021e5124a6c57325ffb02a60cd1d5f40342f8aa (diff) |
documentation: move mtrr.txt to Doc/x86/ subdir
Move mtrr.txt to the Documentation/x86/ subdirectory.
Add 00-INDEX to the Documentation/x86/ subdirectory.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'Documentation/mtrr.txt')
-rw-r--r-- | Documentation/mtrr.txt | 305 |
1 files changed, 0 insertions, 305 deletions
diff --git a/Documentation/mtrr.txt b/Documentation/mtrr.txt deleted file mode 100644 index c39ac395970e..000000000000 --- a/Documentation/mtrr.txt +++ /dev/null | |||
@@ -1,305 +0,0 @@ | |||
1 | MTRR (Memory Type Range Register) control | ||
2 | 3 Jun 1999 | ||
3 | Richard Gooch | ||
4 | <rgooch@atnf.csiro.au> | ||
5 | |||
6 | On Intel P6 family processors (Pentium Pro, Pentium II and later) | ||
7 | the Memory Type Range Registers (MTRRs) may be used to control | ||
8 | processor access to memory ranges. This is most useful when you have | ||
9 | a video (VGA) card on a PCI or AGP bus. Enabling write-combining | ||
10 | allows bus write transfers to be combined into a larger transfer | ||
11 | before bursting over the PCI/AGP bus. This can increase performance | ||
12 | of image write operations 2.5 times or more. | ||
13 | |||
14 | The Cyrix 6x86, 6x86MX and M II processors have Address Range | ||
15 | Registers (ARRs) which provide a similar functionality to MTRRs. For | ||
16 | these, the ARRs are used to emulate the MTRRs. | ||
17 | |||
18 | The AMD K6-2 (stepping 8 and above) and K6-3 processors have two | ||
19 | MTRRs. These are supported. The AMD Athlon family provide 8 Intel | ||
20 | style MTRRs. | ||
21 | |||
22 | The Centaur C6 (WinChip) has 8 MCRs, allowing write-combining. These | ||
23 | are supported. | ||
24 | |||
25 | The VIA Cyrix III and VIA C3 CPUs offer 8 Intel style MTRRs. | ||
26 | |||
27 | The CONFIG_MTRR option creates a /proc/mtrr file which may be used | ||
28 | to manipulate your MTRRs. Typically the X server should use | ||
29 | this. This should have a reasonably generic interface so that | ||
30 | similar control registers on other processors can be easily | ||
31 | supported. | ||
32 | |||
33 | |||
34 | There are two interfaces to /proc/mtrr: one is an ASCII interface | ||
35 | which allows you to read and write. The other is an ioctl() | ||
36 | interface. The ASCII interface is meant for administration. The | ||
37 | ioctl() interface is meant for C programs (i.e. the X server). The | ||
38 | interfaces are described below, with sample commands and C code. | ||
39 | |||
40 | =============================================================================== | ||
41 | Reading MTRRs from the shell: | ||
42 | |||
43 | % cat /proc/mtrr | ||
44 | reg00: base=0x00000000 ( 0MB), size= 128MB: write-back, count=1 | ||
45 | reg01: base=0x08000000 ( 128MB), size= 64MB: write-back, count=1 | ||
46 | =============================================================================== | ||
47 | Creating MTRRs from the C-shell: | ||
48 | # echo "base=0xf8000000 size=0x400000 type=write-combining" >! /proc/mtrr | ||
49 | or if you use bash: | ||
50 | # echo "base=0xf8000000 size=0x400000 type=write-combining" >| /proc/mtrr | ||
51 | |||
52 | And the result thereof: | ||
53 | % cat /proc/mtrr | ||
54 | reg00: base=0x00000000 ( 0MB), size= 128MB: write-back, count=1 | ||
55 | reg01: base=0x08000000 ( 128MB), size= 64MB: write-back, count=1 | ||
56 | reg02: base=0xf8000000 (3968MB), size= 4MB: write-combining, count=1 | ||
57 | |||
58 | This is for video RAM at base address 0xf8000000 and size 4 megabytes. To | ||
59 | find out your base address, you need to look at the output of your X | ||
60 | server, which tells you where the linear framebuffer address is. A | ||
61 | typical line that you may get is: | ||
62 | |||
63 | (--) S3: PCI: 968 rev 0, Linear FB @ 0xf8000000 | ||
64 | |||
65 | Note that you should only use the value from the X server, as it may | ||
66 | move the framebuffer base address, so the only value you can trust is | ||
67 | that reported by the X server. | ||
68 | |||
69 | To find out the size of your framebuffer (what, you don't actually | ||
70 | know?), the following line will tell you: | ||
71 | |||
72 | (--) S3: videoram: 4096k | ||
73 | |||
74 | That's 4 megabytes, which is 0x400000 bytes (in hexadecimal). | ||
75 | A patch is being written for XFree86 which will make this automatic: | ||
76 | in other words the X server will manipulate /proc/mtrr using the | ||
77 | ioctl() interface, so users won't have to do anything. If you use a | ||
78 | commercial X server, lobby your vendor to add support for MTRRs. | ||
79 | =============================================================================== | ||
80 | Creating overlapping MTRRs: | ||
81 | |||
82 | %echo "base=0xfb000000 size=0x1000000 type=write-combining" >/proc/mtrr | ||
83 | %echo "base=0xfb000000 size=0x1000 type=uncachable" >/proc/mtrr | ||
84 | |||
85 | And the results: cat /proc/mtrr | ||
86 | reg00: base=0x00000000 ( 0MB), size= 64MB: write-back, count=1 | ||
87 | reg01: base=0xfb000000 (4016MB), size= 16MB: write-combining, count=1 | ||
88 | reg02: base=0xfb000000 (4016MB), size= 4kB: uncachable, count=1 | ||
89 | |||
90 | Some cards (especially Voodoo Graphics boards) need this 4 kB area | ||
91 | excluded from the beginning of the region because it is used for | ||
92 | registers. | ||
93 | |||
94 | NOTE: You can only create type=uncachable region, if the first | ||
95 | region that you created is type=write-combining. | ||
96 | =============================================================================== | ||
97 | Removing MTRRs from the C-shell: | ||
98 | % echo "disable=2" >! /proc/mtrr | ||
99 | or using bash: | ||
100 | % echo "disable=2" >| /proc/mtrr | ||
101 | =============================================================================== | ||
102 | Reading MTRRs from a C program using ioctl()'s: | ||
103 | |||
104 | /* mtrr-show.c | ||
105 | |||
106 | Source file for mtrr-show (example program to show MTRRs using ioctl()'s) | ||
107 | |||
108 | Copyright (C) 1997-1998 Richard Gooch | ||
109 | |||
110 | This program is free software; you can redistribute it and/or modify | ||
111 | it under the terms of the GNU General Public License as published by | ||
112 | the Free Software Foundation; either version 2 of the License, or | ||
113 | (at your option) any later version. | ||
114 | |||
115 | This program is distributed in the hope that it will be useful, | ||
116 | but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
117 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
118 | GNU General Public License for more details. | ||
119 | |||
120 | You should have received a copy of the GNU General Public License | ||
121 | along with this program; if not, write to the Free Software | ||
122 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | ||
123 | |||
124 | Richard Gooch may be reached by email at rgooch@atnf.csiro.au | ||
125 | The postal address is: | ||
126 | Richard Gooch, c/o ATNF, P. O. Box 76, Epping, N.S.W., 2121, Australia. | ||
127 | */ | ||
128 | |||
129 | /* | ||
130 | This program will use an ioctl() on /proc/mtrr to show the current MTRR | ||
131 | settings. This is an alternative to reading /proc/mtrr. | ||
132 | |||
133 | |||
134 | Written by Richard Gooch 17-DEC-1997 | ||
135 | |||
136 | Last updated by Richard Gooch 2-MAY-1998 | ||
137 | |||
138 | |||
139 | */ | ||
140 | #include <stdio.h> | ||
141 | #include <stdlib.h> | ||
142 | #include <string.h> | ||
143 | #include <sys/types.h> | ||
144 | #include <sys/stat.h> | ||
145 | #include <fcntl.h> | ||
146 | #include <sys/ioctl.h> | ||
147 | #include <errno.h> | ||
148 | #include <asm/mtrr.h> | ||
149 | |||
150 | #define TRUE 1 | ||
151 | #define FALSE 0 | ||
152 | #define ERRSTRING strerror (errno) | ||
153 | |||
154 | static char *mtrr_strings[MTRR_NUM_TYPES] = | ||
155 | { | ||
156 | "uncachable", /* 0 */ | ||
157 | "write-combining", /* 1 */ | ||
158 | "?", /* 2 */ | ||
159 | "?", /* 3 */ | ||
160 | "write-through", /* 4 */ | ||
161 | "write-protect", /* 5 */ | ||
162 | "write-back", /* 6 */ | ||
163 | }; | ||
164 | |||
165 | int main () | ||
166 | { | ||
167 | int fd; | ||
168 | struct mtrr_gentry gentry; | ||
169 | |||
170 | if ( ( fd = open ("/proc/mtrr", O_RDONLY, 0) ) == -1 ) | ||
171 | { | ||
172 | if (errno == ENOENT) | ||
173 | { | ||
174 | fputs ("/proc/mtrr not found: not supported or you don't have a PPro?\n", | ||
175 | stderr); | ||
176 | exit (1); | ||
177 | } | ||
178 | fprintf (stderr, "Error opening /proc/mtrr\t%s\n", ERRSTRING); | ||
179 | exit (2); | ||
180 | } | ||
181 | for (gentry.regnum = 0; ioctl (fd, MTRRIOC_GET_ENTRY, &gentry) == 0; | ||
182 | ++gentry.regnum) | ||
183 | { | ||
184 | if (gentry.size < 1) | ||
185 | { | ||
186 | fprintf (stderr, "Register: %u disabled\n", gentry.regnum); | ||
187 | continue; | ||
188 | } | ||
189 | fprintf (stderr, "Register: %u base: 0x%lx size: 0x%lx type: %s\n", | ||
190 | gentry.regnum, gentry.base, gentry.size, | ||
191 | mtrr_strings[gentry.type]); | ||
192 | } | ||
193 | if (errno == EINVAL) exit (0); | ||
194 | fprintf (stderr, "Error doing ioctl(2) on /dev/mtrr\t%s\n", ERRSTRING); | ||
195 | exit (3); | ||
196 | } /* End Function main */ | ||
197 | =============================================================================== | ||
198 | Creating MTRRs from a C programme using ioctl()'s: | ||
199 | |||
200 | /* mtrr-add.c | ||
201 | |||
202 | Source file for mtrr-add (example programme to add an MTRRs using ioctl()) | ||
203 | |||
204 | Copyright (C) 1997-1998 Richard Gooch | ||
205 | |||
206 | This program is free software; you can redistribute it and/or modify | ||
207 | it under the terms of the GNU General Public License as published by | ||
208 | the Free Software Foundation; either version 2 of the License, or | ||
209 | (at your option) any later version. | ||
210 | |||
211 | This program is distributed in the hope that it will be useful, | ||
212 | but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
213 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
214 | GNU General Public License for more details. | ||
215 | |||
216 | You should have received a copy of the GNU General Public License | ||
217 | along with this program; if not, write to the Free Software | ||
218 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | ||
219 | |||
220 | Richard Gooch may be reached by email at rgooch@atnf.csiro.au | ||
221 | The postal address is: | ||
222 | Richard Gooch, c/o ATNF, P. O. Box 76, Epping, N.S.W., 2121, Australia. | ||
223 | */ | ||
224 | |||
225 | /* | ||
226 | This programme will use an ioctl() on /proc/mtrr to add an entry. The first | ||
227 | available mtrr is used. This is an alternative to writing /proc/mtrr. | ||
228 | |||
229 | |||
230 | Written by Richard Gooch 17-DEC-1997 | ||
231 | |||
232 | Last updated by Richard Gooch 2-MAY-1998 | ||
233 | |||
234 | |||
235 | */ | ||
236 | #include <stdio.h> | ||
237 | #include <string.h> | ||
238 | #include <stdlib.h> | ||
239 | #include <unistd.h> | ||
240 | #include <sys/types.h> | ||
241 | #include <sys/stat.h> | ||
242 | #include <fcntl.h> | ||
243 | #include <sys/ioctl.h> | ||
244 | #include <errno.h> | ||
245 | #include <asm/mtrr.h> | ||
246 | |||
247 | #define TRUE 1 | ||
248 | #define FALSE 0 | ||
249 | #define ERRSTRING strerror (errno) | ||
250 | |||
251 | static char *mtrr_strings[MTRR_NUM_TYPES] = | ||
252 | { | ||
253 | "uncachable", /* 0 */ | ||
254 | "write-combining", /* 1 */ | ||
255 | "?", /* 2 */ | ||
256 | "?", /* 3 */ | ||
257 | "write-through", /* 4 */ | ||
258 | "write-protect", /* 5 */ | ||
259 | "write-back", /* 6 */ | ||
260 | }; | ||
261 | |||
262 | int main (int argc, char **argv) | ||
263 | { | ||
264 | int fd; | ||
265 | struct mtrr_sentry sentry; | ||
266 | |||
267 | if (argc != 4) | ||
268 | { | ||
269 | fprintf (stderr, "Usage:\tmtrr-add base size type\n"); | ||
270 | exit (1); | ||
271 | } | ||
272 | sentry.base = strtoul (argv[1], NULL, 0); | ||
273 | sentry.size = strtoul (argv[2], NULL, 0); | ||
274 | for (sentry.type = 0; sentry.type < MTRR_NUM_TYPES; ++sentry.type) | ||
275 | { | ||
276 | if (strcmp (argv[3], mtrr_strings[sentry.type]) == 0) break; | ||
277 | } | ||
278 | if (sentry.type >= MTRR_NUM_TYPES) | ||
279 | { | ||
280 | fprintf (stderr, "Illegal type: \"%s\"\n", argv[3]); | ||
281 | exit (2); | ||
282 | } | ||
283 | if ( ( fd = open ("/proc/mtrr", O_WRONLY, 0) ) == -1 ) | ||
284 | { | ||
285 | if (errno == ENOENT) | ||
286 | { | ||
287 | fputs ("/proc/mtrr not found: not supported or you don't have a PPro?\n", | ||
288 | stderr); | ||
289 | exit (3); | ||
290 | } | ||
291 | fprintf (stderr, "Error opening /proc/mtrr\t%s\n", ERRSTRING); | ||
292 | exit (4); | ||
293 | } | ||
294 | if (ioctl (fd, MTRRIOC_ADD_ENTRY, &sentry) == -1) | ||
295 | { | ||
296 | fprintf (stderr, "Error doing ioctl(2) on /dev/mtrr\t%s\n", ERRSTRING); | ||
297 | exit (5); | ||
298 | } | ||
299 | fprintf (stderr, "Sleeping for 5 seconds so you can see the new entry\n"); | ||
300 | sleep (5); | ||
301 | close (fd); | ||
302 | fputs ("I've just closed /proc/mtrr so now the new entry should be gone\n", | ||
303 | stderr); | ||
304 | } /* End Function main */ | ||
305 | =============================================================================== | ||