Re: [PATCH 10/27] Documentation: x86: convert mtrr.txt to reST

From: Mauro Carvalho Chehab
Date: Sat Apr 27 2019 - 14:11:08 EST

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Em Sat, 27 Apr 2019 14:32:13 -0300
Mauro Carvalho Chehab <mchehab+samsung@xxxxxxxxxx> escreveu:

> Em Fri, 26 Apr 2019 23:31:33 +0800
> Changbin Du <changbin.du@xxxxxxxxx> escreveu:
>
> > This converts the plain text documentation to reStructuredText format and
> > add it to Sphinx TOC tree. No essential content change.
> >
> > Signed-off-by: Changbin Du <changbin.du@xxxxxxxxx>
> > ---
> > Documentation/x86/index.rst | 1 +
> > Documentation/x86/mtrr.rst | 350 ++++++++++++++++++++++++++++++++++++
> > Documentation/x86/mtrr.txt | 329 ---------------------------------
> > 3 files changed, 351 insertions(+), 329 deletions(-)
> > create mode 100644 Documentation/x86/mtrr.rst
> > delete mode 100644 Documentation/x86/mtrr.txt
> >
> > diff --git a/Documentation/x86/index.rst b/Documentation/x86/index.rst
> > index fd54b859db9b..d805962a7238 100644
> > --- a/Documentation/x86/index.rst
> > +++ b/Documentation/x86/index.rst
> > @@ -16,3 +16,4 @@ Linux x86 Support
> > earlyprintk
> > zero-page
> > tlb
> > + mtrr
> > diff --git a/Documentation/x86/mtrr.rst b/Documentation/x86/mtrr.rst
> > new file mode 100644
> > index 000000000000..72da61022861
> > --- /dev/null
> > +++ b/Documentation/x86/mtrr.rst
> > @@ -0,0 +1,350 @@
> > +.. SPDX-License-Identifier: GPL-2.0
> > +
> > +=========================================
> > +MTRR (Memory Type Range Register) control
> > +=========================================
> > +
> > +:Ahthors: - Richard Gooch <rgooch@xxxxxxxxxxxxx> - 3 Jun 1999
> > + - Luis R. Rodriguez <mcgrof@xxxxxxxxxxxxxxxx> - April 9, 2015
>
> Typo: Authors
>
> > +
> > +
> > +Phasing out MTRR use
> > +====================
> > +
> > +MTRR use is replaced on modern x86 hardware with PAT. Direct MTRR use by
> > +drivers on Linux is now completely phased out, device drivers should use
> > +arch_phys_wc_add() in combination with ioremap_wc() to make MTRR effective on
> > +non-PAT systems while a no-op but equally effective on PAT enabled systems.
> > +
> > +Even if Linux does not use MTRRs directly, some x86 platform firmware may still
> > +set up MTRRs early before booting the OS. They do this as some platform
> > +firmware may still have implemented access to MTRRs which would be controlled
> > +and handled by the platform firmware directly. An example of platform use of
> > +MTRRs is through the use of SMI handlers, one case could be for fan control,
> > +the platform code would need uncachable access to some of its fan control
> > +registers. Such platform access does not need any Operating System MTRR code in
> > +place other than mtrr_type_lookup() to ensure any OS specific mapping requests
> > +are aligned with platform MTRR setup. If MTRRs are only set up by the platform
> > +firmware code though and the OS does not make any specific MTRR mapping
> > +requests mtrr_type_lookup() should always return MTRR_TYPE_INVALID.
> > +
> > +For details refer to :doc:`x86/pat`.

In time: the reference above is broken:

Documentation/x86/mtrr.rst:31: WARNING: unknown document: x86/pat

It should be, instead:

:doc:`pat`

>
> I'm in doubt about the block below:
>
> > +
> > +On Intel P6 family processors (Pentium Pro, Pentium II and later)
> > +the Memory Type Range Registers (MTRRs) may be used to control
> > +processor access to memory ranges. This is most useful when you have
> > +a video (VGA) card on a PCI or AGP bus. Enabling write-combining
> > +allows bus write transfers to be combined into a larger transfer
> > +before bursting over the PCI/AGP bus. This can increase performance
> > +of image write operations 2.5 times or more.
> > +
> > +The Cyrix 6x86, 6x86MX and M II processors have Address Range
> > +Registers (ARRs) which provide a similar functionality to MTRRs. For
> > +these, the ARRs are used to emulate the MTRRs.
> > +
> > +The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
> > +MTRRs. These are supported. The AMD Athlon family provide 8 Intel
> > +style MTRRs.
> > +
> > +The Centaur C6 (WinChip) has 8 MCRs, allowing write-combining. These
> > +are supported.
> > +
> > +The VIA Cyrix III and VIA C3 CPUs offer 8 Intel style MTRRs.
> > +
> > +The CONFIG_MTRR option creates a /proc/mtrr file which may be used
> > +to manipulate your MTRRs. Typically the X server should use
> > +this. This should have a reasonably generic interface so that
> > +similar control registers on other processors can be easily
> > +supported.
>
> All the above were originally indented, and marked by an horizontal
> bar (together with the next paragraph).
>
> Perhaps the intention there were to mark them as some sort of per-CPU
> type notes.
>
> Anyway, I would preserve the original indentation - possibly
> replacing the horizontal bar using non-ReST standard:
>
> ===============================================================================
>
> By the ReST equivalent:
>
> -------------------------------------------------------------------------------
>
> Later, if x86 maintainers thing it is worth, they could add a note markup
> before the block.
>
> > +
> > +There are two interfaces to /proc/mtrr: one is an ASCII interface
> > +which allows you to read and write. The other is an ioctl()
> > +interface. The ASCII interface is meant for administration. The
> > +ioctl() interface is meant for C programs (i.e. the X server). The
> > +interfaces are described below, with sample commands and C code.
> > +
> > +Reading MTRRs from the shell::
> > +
> > + % cat /proc/mtrr
> > + reg00: base=0x00000000 ( 0MB), size= 128MB: write-back, count=1
> > + reg01: base=0x08000000 ( 128MB), size= 64MB: write-back, count=1
> > +
> > +Creating MTRRs from the C-shell::
> > +
> > + # echo "base=0xf8000000 size=0x400000 type=write-combining" >! /proc/mtrr
> > +
> > +or if you use bash::
> > +
> > + # echo "base=0xf8000000 size=0x400000 type=write-combining" >| /proc/mtrr
> > +
> > +And the result thereof::
> > +
> > + % cat /proc/mtrr
> > + reg00: base=0x00000000 ( 0MB), size= 128MB: write-back, count=1
> > + reg01: base=0x08000000 ( 128MB), size= 64MB: write-back, count=1
> > + reg02: base=0xf8000000 (3968MB), size= 4MB: write-combining, count=1
> > +
> > +This is for video RAM at base address 0xf8000000 and size 4 megabytes. To
> > +find out your base address, you need to look at the output of your X
> > +server, which tells you where the linear framebuffer address is. A
> > +typical line that you may get is:
> > +
> > +(--) S3: PCI: 968 rev 0, Linear FB @ 0xf8000000
> > +
> > +Note that you should only use the value from the X server, as it may
> > +move the framebuffer base address, so the only value you can trust is
> > +that reported by the X server.
> > +
> > +To find out the size of your framebuffer (what, you don't actually
> > +know?), the following line will tell you:
> > +
> > +(--) S3: videoram: 4096k
> > +
> > +That's 4 megabytes, which is 0x400000 bytes (in hexadecimal).
> > +A patch is being written for XFree86 which will make this automatic:
> > +in other words the X server will manipulate /proc/mtrr using the
> > +ioctl() interface, so users won't have to do anything. If you use a
> > +commercial X server, lobby your vendor to add support for MTRRs.
> > +
> > +
> > +Creating overlapping MTRRs
> > +==========================
> > +::
> > +
> > + %echo "base=0xfb000000 size=0x1000000 type=write-combining" >/proc/mtrr
> > + %echo "base=0xfb000000 size=0x1000 type=uncachable" >/proc/mtrr
> > +
> > +And the results::
> > +
> > + % cat /proc/mtrr
> > + reg00: base=0x00000000 ( 0MB), size= 64MB: write-back, count=1
> > + reg01: base=0xfb000000 (4016MB), size= 16MB: write-combining, count=1
> > + reg02: base=0xfb000000 (4016MB), size= 4kB: uncachable, count=1
> > +
> > +Some cards (especially Voodoo Graphics boards) need this 4 kB area
> > +excluded from the beginning of the region because it is used for
> > +registers.
> > +
> > +NOTE: You can only create type=uncachable region, if the first
> > +region that you created is type=write-combining.
>
> If you don't want to use a note markup, I would, at least, do:
>
> Note:
> You can only create type=uncachable region, if the first
> region that you created is type=write-combining.
>
> > +
> > +
> > +Removing MTRRs from the C-shel
> > +==============================
>
> There's also a typo above: C-shel -> C-shell...
>
> > +::
> > +
> > + % echo "disable=2" >! /proc/mtrr
> > +
> > +or using bash::
> > +
> > + % echo "disable=2" >| /proc/mtrr
>
>
> Yet, I would, instead rewrite this block as:
>
>
> Removing MTRRs
> ==============
>
> Using C-shell::
>
> % echo "disable=2" >! /proc/mtrr
>
> or using bash::
>
> % echo "disable=2" >| /proc/mtrr
>
>
> As it contains both csh and bash instructions there.
>
> > +
> > +
> > +Reading MTRRs from a C program using ioctl()'s
> > +==============================================
> > +::
> > +
> > + /* mtrr-show.c
> > +
> > + Source file for mtrr-show (example program to show MTRRs using ioctl()'s)
> > +
> > + Copyright (C) 1997-1998 Richard Gooch
> > +
> > + This program is free software; you can redistribute it and/or modify
> > + it under the terms of the GNU General Public License as published by
> > + the Free Software Foundation; either version 2 of the License, or
> > + (at your option) any later version.
> > +
> > + This program is distributed in the hope that it will be useful,
> > + but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > + GNU General Public License for more details.
> > +
> > + You should have received a copy of the GNU General Public License
> > + along with this program; if not, write to the Free Software
> > + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> > +
> > + Richard Gooch may be reached by email at rgooch@xxxxxxxxxxxxx
> > + The postal address is:
> > + Richard Gooch, c/o ATNF, P. O. Box 76, Epping, N.S.W., 2121, Australia.
> > + */
> > +
> > + /*
> > + This program will use an ioctl() on /proc/mtrr to show the current MTRR
> > + settings. This is an alternative to reading /proc/mtrr.
> > +
> > +
> > + Written by Richard Gooch 17-DEC-1997
> > +
> > + Last updated by Richard Gooch 2-MAY-1998
> > +
> > +
> > + */
> > + #include <stdio.h>
> > + #include <stdlib.h>
> > + #include <string.h>
> > + #include <sys/types.h>
> > + #include <sys/stat.h>
> > + #include <fcntl.h>
> > + #include <sys/ioctl.h>
> > + #include <errno.h>
> > + #include <asm/mtrr.h>
> > +
> > + #define TRUE 1
> > + #define FALSE 0
> > + #define ERRSTRING strerror (errno)
> > +
> > + static char *mtrr_strings[MTRR_NUM_TYPES] =
> > + {
> > + "uncachable", /* 0 */
> > + "write-combining", /* 1 */
> > + "?", /* 2 */
> > + "?", /* 3 */
> > + "write-through", /* 4 */
> > + "write-protect", /* 5 */
> > + "write-back", /* 6 */
> > + };
> > +
> > + int main ()
> > + {
> > + int fd;
> > + struct mtrr_gentry gentry;
> > +
> > + if ( ( fd = open ("/proc/mtrr", O_RDONLY, 0) ) == -1 )
> > + {
> > + if (errno == ENOENT)
> > + {
> > + fputs ("/proc/mtrr not found: not supported or you don't have a PPro?\n",
> > + stderr);
> > + exit (1);
> > + }
> > + fprintf (stderr, "Error opening /proc/mtrr\t%s\n", ERRSTRING);
> > + exit (2);
> > + }
> > + for (gentry.regnum = 0; ioctl (fd, MTRRIOC_GET_ENTRY, &gentry) == 0;
> > + ++gentry.regnum)
> > + {
> > + if (gentry.size < 1)
> > + {
> > + fprintf (stderr, "Register: %u disabled\n", gentry.regnum);
> > + continue;
> > + }
> > + fprintf (stderr, "Register: %u base: 0x%lx size: 0x%lx type: %s\n",
> > + gentry.regnum, gentry.base, gentry.size,
> > + mtrr_strings[gentry.type]);
> > + }
> > + if (errno == EINVAL) exit (0);
> > + fprintf (stderr, "Error doing ioctl(2) on /dev/mtrr\t%s\n", ERRSTRING);
> > + exit (3);
> > + } /* End Function main */
> > +
> > +
> > +Creating MTRRs from a C programme using ioctl()'s
> > +=================================================
> > +::
> > +
> > + /* mtrr-add.c
> > +
> > + Source file for mtrr-add (example programme to add an MTRRs using ioctl())
> > +
> > + Copyright (C) 1997-1998 Richard Gooch
> > +
> > + This program is free software; you can redistribute it and/or modify
> > + it under the terms of the GNU General Public License as published by
> > + the Free Software Foundation; either version 2 of the License, or
> > + (at your option) any later version.
> > +
> > + This program is distributed in the hope that it will be useful,
> > + but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > + GNU General Public License for more details.
> > +
> > + You should have received a copy of the GNU General Public License
> > + along with this program; if not, write to the Free Software
> > + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> > +
> > + Richard Gooch may be reached by email at rgooch@xxxxxxxxxxxxx
> > + The postal address is:
> > + Richard Gooch, c/o ATNF, P. O. Box 76, Epping, N.S.W., 2121, Australia.
> > + */
> > +
> > + /*
> > + This programme will use an ioctl() on /proc/mtrr to add an entry. The first
> > + available mtrr is used. This is an alternative to writing /proc/mtrr.
> > +
> > +
> > + Written by Richard Gooch 17-DEC-1997
> > +
> > + Last updated by Richard Gooch 2-MAY-1998
> > +
> > +
> > + */
> > + #include <stdio.h>
> > + #include <string.h>
> > + #include <stdlib.h>
> > + #include <unistd.h>
> > + #include <sys/types.h>
> > + #include <sys/stat.h>
> > + #include <fcntl.h>
> > + #include <sys/ioctl.h>
> > + #include <errno.h>
> > + #include <asm/mtrr.h>
> > +
> > + #define TRUE 1
> > + #define FALSE 0
> > + #define ERRSTRING strerror (errno)
> > +
> > + static char *mtrr_strings[MTRR_NUM_TYPES] =
> > + {
> > + "uncachable", /* 0 */
> > + "write-combining", /* 1 */
> > + "?", /* 2 */
> > + "?", /* 3 */
> > + "write-through", /* 4 */
> > + "write-protect", /* 5 */
> > + "write-back", /* 6 */
> > + };
> > +
> > + int main (int argc, char **argv)
> > + {
> > + int fd;
> > + struct mtrr_sentry sentry;
> > +
> > + if (argc != 4)
> > + {
> > + fprintf (stderr, "Usage:\tmtrr-add base size type\n");
> > + exit (1);
> > + }
> > + sentry.base = strtoul (argv[1], NULL, 0);
> > + sentry.size = strtoul (argv[2], NULL, 0);
> > + for (sentry.type = 0; sentry.type < MTRR_NUM_TYPES; ++sentry.type)
> > + {
> > + if (strcmp (argv[3], mtrr_strings[sentry.type]) == 0) break;
> > + }
> > + if (sentry.type >= MTRR_NUM_TYPES)
> > + {
> > + fprintf (stderr, "Illegal type: \"%s\"\n", argv[3]);
> > + exit (2);
> > + }
> > + if ( ( fd = open ("/proc/mtrr", O_WRONLY, 0) ) == -1 )
> > + {
> > + if (errno == ENOENT)
> > + {
> > + fputs ("/proc/mtrr not found: not supported or you don't have a PPro?\n",
> > + stderr);
> > + exit (3);
> > + }
> > + fprintf (stderr, "Error opening /proc/mtrr\t%s\n", ERRSTRING);
> > + exit (4);
> > + }
> > + if (ioctl (fd, MTRRIOC_ADD_ENTRY, &sentry) == -1)
> > + {
> > + fprintf (stderr, "Error doing ioctl(2) on /dev/mtrr\t%s\n", ERRSTRING);
> > + exit (5);
> > + }
> > + fprintf (stderr, "Sleeping for 5 seconds so you can see the new entry\n");
> > + sleep (5);
> > + close (fd);
> > + fputs ("I've just closed /proc/mtrr so now the new entry should be gone\n",
> > + stderr);
> > + } /* End Function main */
> > diff --git a/Documentation/x86/mtrr.txt b/Documentation/x86/mtrr.txt
> > deleted file mode 100644
> > index dc3e703913ac..000000000000
> > --- a/Documentation/x86/mtrr.txt
> > +++ /dev/null
> > @@ -1,329 +0,0 @@
> > -MTRR (Memory Type Range Register) control
> > -
> > -Richard Gooch <rgooch@xxxxxxxxxxxxx> - 3 Jun 1999
> > -Luis R. Rodriguez <mcgrof@xxxxxxxxxxxxxxxx> - April 9, 2015
> > -
> > -===============================================================================
> > -Phasing out MTRR use
> > -
> > -MTRR use is replaced on modern x86 hardware with PAT. Direct MTRR use by
> > -drivers on Linux is now completely phased out, device drivers should use
> > -arch_phys_wc_add() in combination with ioremap_wc() to make MTRR effective on
> > -non-PAT systems while a no-op but equally effective on PAT enabled systems.
> > -
> > -Even if Linux does not use MTRRs directly, some x86 platform firmware may still
> > -set up MTRRs early before booting the OS. They do this as some platform
> > -firmware may still have implemented access to MTRRs which would be controlled
> > -and handled by the platform firmware directly. An example of platform use of
> > -MTRRs is through the use of SMI handlers, one case could be for fan control,
> > -the platform code would need uncachable access to some of its fan control
> > -registers. Such platform access does not need any Operating System MTRR code in
> > -place other than mtrr_type_lookup() to ensure any OS specific mapping requests
> > -are aligned with platform MTRR setup. If MTRRs are only set up by the platform
> > -firmware code though and the OS does not make any specific MTRR mapping
> > -requests mtrr_type_lookup() should always return MTRR_TYPE_INVALID.
> > -
> > -For details refer to Documentation/x86/pat.txt.
> > -
> > -===============================================================================
> > -
> > - On Intel P6 family processors (Pentium Pro, Pentium II and later)
> > - the Memory Type Range Registers (MTRRs) may be used to control
> > - processor access to memory ranges. This is most useful when you have
> > - a video (VGA) card on a PCI or AGP bus. Enabling write-combining
> > - allows bus write transfers to be combined into a larger transfer
> > - before bursting over the PCI/AGP bus. This can increase performance
> > - of image write operations 2.5 times or more.
> > -
> > - The Cyrix 6x86, 6x86MX and M II processors have Address Range
> > - Registers (ARRs) which provide a similar functionality to MTRRs. For
> > - these, the ARRs are used to emulate the MTRRs.
> > -
> > - The AMD K6-2 (stepping 8 and above) and K6-3 processors have two
> > - MTRRs. These are supported. The AMD Athlon family provide 8 Intel
> > - style MTRRs.
> > -
> > - The Centaur C6 (WinChip) has 8 MCRs, allowing write-combining. These
> > - are supported.
> > -
> > - The VIA Cyrix III and VIA C3 CPUs offer 8 Intel style MTRRs.
> > -
> > - The CONFIG_MTRR option creates a /proc/mtrr file which may be used
> > - to manipulate your MTRRs. Typically the X server should use
> > - this. This should have a reasonably generic interface so that
> > - similar control registers on other processors can be easily
> > - supported.
> > -
> > -
> > -There are two interfaces to /proc/mtrr: one is an ASCII interface
> > -which allows you to read and write. The other is an ioctl()
> > -interface. The ASCII interface is meant for administration. The
> > -ioctl() interface is meant for C programs (i.e. the X server). The
> > -interfaces are described below, with sample commands and C code.
> > -
> > -===============================================================================
> > -Reading MTRRs from the shell:
> > -
> > -% cat /proc/mtrr
> > -reg00: base=0x00000000 ( 0MB), size= 128MB: write-back, count=1
> > -reg01: base=0x08000000 ( 128MB), size= 64MB: write-back, count=1
> > -===============================================================================
> > -Creating MTRRs from the C-shell:
> > -# echo "base=0xf8000000 size=0x400000 type=write-combining" >! /proc/mtrr
> > -or if you use bash:
> > -# echo "base=0xf8000000 size=0x400000 type=write-combining" >| /proc/mtrr
> > -
> > -And the result thereof:
> > -% cat /proc/mtrr
> > -reg00: base=0x00000000 ( 0MB), size= 128MB: write-back, count=1
> > -reg01: base=0x08000000 ( 128MB), size= 64MB: write-back, count=1
> > -reg02: base=0xf8000000 (3968MB), size= 4MB: write-combining, count=1
> > -
> > -This is for video RAM at base address 0xf8000000 and size 4 megabytes. To
> > -find out your base address, you need to look at the output of your X
> > -server, which tells you where the linear framebuffer address is. A
> > -typical line that you may get is:
> > -
> > -(--) S3: PCI: 968 rev 0, Linear FB @ 0xf8000000
> > -
> > -Note that you should only use the value from the X server, as it may
> > -move the framebuffer base address, so the only value you can trust is
> > -that reported by the X server.
> > -
> > -To find out the size of your framebuffer (what, you don't actually
> > -know?), the following line will tell you:
> > -
> > -(--) S3: videoram: 4096k
> > -
> > -That's 4 megabytes, which is 0x400000 bytes (in hexadecimal).
> > -A patch is being written for XFree86 which will make this automatic:
> > -in other words the X server will manipulate /proc/mtrr using the
> > -ioctl() interface, so users won't have to do anything. If you use a
> > -commercial X server, lobby your vendor to add support for MTRRs.
> > -===============================================================================
> > -Creating overlapping MTRRs:
> > -
> > -%echo "base=0xfb000000 size=0x1000000 type=write-combining" >/proc/mtrr
> > -%echo "base=0xfb000000 size=0x1000 type=uncachable" >/proc/mtrr
> > -
> > -And the results: cat /proc/mtrr
> > -reg00: base=0x00000000 ( 0MB), size= 64MB: write-back, count=1
> > -reg01: base=0xfb000000 (4016MB), size= 16MB: write-combining, count=1
> > -reg02: base=0xfb000000 (4016MB), size= 4kB: uncachable, count=1
> > -
> > -Some cards (especially Voodoo Graphics boards) need this 4 kB area
> > -excluded from the beginning of the region because it is used for
> > -registers.
> > -
> > -NOTE: You can only create type=uncachable region, if the first
> > -region that you created is type=write-combining.
> > -===============================================================================
> > -Removing MTRRs from the C-shell:
> > -% echo "disable=2" >! /proc/mtrr
> > -or using bash:
> > -% echo "disable=2" >| /proc/mtrr
> > -===============================================================================
> > -Reading MTRRs from a C program using ioctl()'s:
> > -
> > -/* mtrr-show.c
> > -
> > - Source file for mtrr-show (example program to show MTRRs using ioctl()'s)
> > -
> > - Copyright (C) 1997-1998 Richard Gooch
> > -
> > - This program is free software; you can redistribute it and/or modify
> > - it under the terms of the GNU General Public License as published by
> > - the Free Software Foundation; either version 2 of the License, or
> > - (at your option) any later version.
> > -
> > - This program is distributed in the hope that it will be useful,
> > - but WITHOUT ANY WARRANTY; without even the implied warranty of
> > - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > - GNU General Public License for more details.
> > -
> > - You should have received a copy of the GNU General Public License
> > - along with this program; if not, write to the Free Software
> > - Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> > -
> > - Richard Gooch may be reached by email at rgooch@xxxxxxxxxxxxx
> > - The postal address is:
> > - Richard Gooch, c/o ATNF, P. O. Box 76, Epping, N.S.W., 2121, Australia.
> > -*/
> > -
> > -/*
> > - This program will use an ioctl() on /proc/mtrr to show the current MTRR
> > - settings. This is an alternative to reading /proc/mtrr.
> > -
> > -
> > - Written by Richard Gooch 17-DEC-1997
> > -
> > - Last updated by Richard Gooch 2-MAY-1998
> > -
> > -
> > -*/
> > -#include <stdio.h>
> > -#include <stdlib.h>
> > -#include <string.h>
> > -#include <sys/types.h>
> > -#include <sys/stat.h>
> > -#include <fcntl.h>
> > -#include <sys/ioctl.h>
> > -#include <errno.h>
> > -#include <asm/mtrr.h>
> > -
> > -#define TRUE 1
> > -#define FALSE 0
> > -#define ERRSTRING strerror (errno)
> > -
> > -static char *mtrr_strings[MTRR_NUM_TYPES] =
> > -{
> > - "uncachable", /* 0 */
> > - "write-combining", /* 1 */
> > - "?", /* 2 */
> > - "?", /* 3 */
> > - "write-through", /* 4 */
> > - "write-protect", /* 5 */
> > - "write-back", /* 6 */
> > -};
> > -
> > -int main ()
> > -{
> > - int fd;
> > - struct mtrr_gentry gentry;
> > -
> > - if ( ( fd = open ("/proc/mtrr", O_RDONLY, 0) ) == -1 )
> > - {
> > - if (errno == ENOENT)
> > - {
> > - fputs ("/proc/mtrr not found: not supported or you don't have a PPro?\n",
> > - stderr);
> > - exit (1);
> > - }
> > - fprintf (stderr, "Error opening /proc/mtrr\t%s\n", ERRSTRING);
> > - exit (2);
> > - }
> > - for (gentry.regnum = 0; ioctl (fd, MTRRIOC_GET_ENTRY, &gentry) == 0;
> > - ++gentry.regnum)
> > - {
> > - if (gentry.size < 1)
> > - {
> > - fprintf (stderr, "Register: %u disabled\n", gentry.regnum);
> > - continue;
> > - }
> > - fprintf (stderr, "Register: %u base: 0x%lx size: 0x%lx type: %s\n",
> > - gentry.regnum, gentry.base, gentry.size,
> > - mtrr_strings[gentry.type]);
> > - }
> > - if (errno == EINVAL) exit (0);
> > - fprintf (stderr, "Error doing ioctl(2) on /dev/mtrr\t%s\n", ERRSTRING);
> > - exit (3);
> > -} /* End Function main */
> > -===============================================================================
> > -Creating MTRRs from a C programme using ioctl()'s:
> > -
> > -/* mtrr-add.c
> > -
> > - Source file for mtrr-add (example programme to add an MTRRs using ioctl())
> > -
> > - Copyright (C) 1997-1998 Richard Gooch
> > -
> > - This program is free software; you can redistribute it and/or modify
> > - it under the terms of the GNU General Public License as published by
> > - the Free Software Foundation; either version 2 of the License, or
> > - (at your option) any later version.
> > -
> > - This program is distributed in the hope that it will be useful,
> > - but WITHOUT ANY WARRANTY; without even the implied warranty of
> > - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> > - GNU General Public License for more details.
> > -
> > - You should have received a copy of the GNU General Public License
> > - along with this program; if not, write to the Free Software
> > - Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> > -
> > - Richard Gooch may be reached by email at rgooch@xxxxxxxxxxxxx
> > - The postal address is:
> > - Richard Gooch, c/o ATNF, P. O. Box 76, Epping, N.S.W., 2121, Australia.
> > -*/
> > -
> > -/*
> > - This programme will use an ioctl() on /proc/mtrr to add an entry. The first
> > - available mtrr is used. This is an alternative to writing /proc/mtrr.
> > -
> > -
> > - Written by Richard Gooch 17-DEC-1997
> > -
> > - Last updated by Richard Gooch 2-MAY-1998
> > -
> > -
> > -*/
> > -#include <stdio.h>
> > -#include <string.h>
> > -#include <stdlib.h>
> > -#include <unistd.h>
> > -#include <sys/types.h>
> > -#include <sys/stat.h>
> > -#include <fcntl.h>
> > -#include <sys/ioctl.h>
> > -#include <errno.h>
> > -#include <asm/mtrr.h>
> > -
> > -#define TRUE 1
> > -#define FALSE 0
> > -#define ERRSTRING strerror (errno)
> > -
> > -static char *mtrr_strings[MTRR_NUM_TYPES] =
> > -{
> > - "uncachable", /* 0 */
> > - "write-combining", /* 1 */
> > - "?", /* 2 */
> > - "?", /* 3 */
> > - "write-through", /* 4 */
> > - "write-protect", /* 5 */
> > - "write-back", /* 6 */
> > -};
> > -
> > -int main (int argc, char **argv)
> > -{
> > - int fd;
> > - struct mtrr_sentry sentry;
> > -
> > - if (argc != 4)
> > - {
> > - fprintf (stderr, "Usage:\tmtrr-add base size type\n");
> > - exit (1);
> > - }
> > - sentry.base = strtoul (argv[1], NULL, 0);
> > - sentry.size = strtoul (argv[2], NULL, 0);
> > - for (sentry.type = 0; sentry.type < MTRR_NUM_TYPES; ++sentry.type)
> > - {
> > - if (strcmp (argv[3], mtrr_strings[sentry.type]) == 0) break;
> > - }
> > - if (sentry.type >= MTRR_NUM_TYPES)
> > - {
> > - fprintf (stderr, "Illegal type: \"%s\"\n", argv[3]);
> > - exit (2);
> > - }
> > - if ( ( fd = open ("/proc/mtrr", O_WRONLY, 0) ) == -1 )
> > - {
> > - if (errno == ENOENT)
> > - {
> > - fputs ("/proc/mtrr not found: not supported or you don't have a PPro?\n",
> > - stderr);
> > - exit (3);
> > - }
> > - fprintf (stderr, "Error opening /proc/mtrr\t%s\n", ERRSTRING);
> > - exit (4);
> > - }
> > - if (ioctl (fd, MTRRIOC_ADD_ENTRY, &sentry) == -1)
> > - {
> > - fprintf (stderr, "Error doing ioctl(2) on /dev/mtrr\t%s\n", ERRSTRING);
> > - exit (5);
> > - }
> > - fprintf (stderr, "Sleeping for 5 seconds so you can see the new entry\n");
> > - sleep (5);
> > - close (fd);
> > - fputs ("I've just closed /proc/mtrr so now the new entry should be gone\n",
> > - stderr);
> > -} /* End Function main */
> > -===============================================================================
>
>
>
> Thanks,
> Mauro

Thanks,
Mauro

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