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Date:   Sat, 27 Apr 2019 15:10:48 -0300
From:   Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
To:     Changbin Du <changbin.du@gmail.com>
Cc:     Jonathan Corbet <corbet@lwn.net>, tglx@linutronix.de,
        mingo@redhat.com, bp@alien8.de, x86@kernel.org,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 10/27] Documentation: x86: convert mtrr.txt to reST
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In-Reply-To: <20190427143213.3c0d2286@coco.lan>
References: <20190426153150.21228-1-changbin.du@gmail.com>
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Em Sat, 27 Apr 2019 14:32:13 -0300
Mauro Carvalho Chehab <mchehab+samsung@kernel.org> escreveu:

> Em Fri, 26 Apr 2019 23:31:33 +0800
> Changbin Du <changbin.du@gmail.com> 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@gmail.com>
> > ---
> >  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@atnf.csiro.au> - 3 Jun 1999
> > +          - Luis R. Rodriguez <mcgrof@do-not-panic.com> - 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@atnf.csiro.au
> > +      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@atnf.csiro.au
> > +      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@atnf.csiro.au> - 3 Jun 1999
> > -Luis R. Rodriguez <mcgrof@do-not-panic.com> - 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@atnf.csiro.au
> > -    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@atnf.csiro.au
> > -    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