[PATCH 0/3] mem.4 updates

[PATCH 0/3] mem.4 updates

[Elie De Brauwer]

Hello Michael,

Attached are three patches which modify mem.4:
 - One explains that /dev/kmem is only accessisble if CONFIG_DEVKMEM is set
 - Another one which fixes an error in the group name used in the example
   to create /dev/port.
 - A last one which explains the impact of the CONFIG_STRICT_DEVMEM option
   on /dev/mem.

my 2 cents
E.


Elie De Brauwer (3):
  mem.4: /dev/kmem depends on CONFIG_DEVKMEM
  mem.4: correct /dev/port group in example
  mem.4: Add CONFIG_STRICT_DEVMEM

 man4/mem.4 | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

-- 
2.1.3

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[PATCH 1/3] mem.4: /dev/kmem depends on CONFIG_DEVKMEM

[Elie De Brauwer]

Since 2.6.26 /dev/kmem depends on the CONFIG_DEVKMEM to be set.

See:
 - changelog: http://kernelnewbies.org/Linux_2_6_26
 - commit: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b781ecb6a379f155568ef7093e38c6c1d857fe53

Signed-off-by: Elie De Brauwer <eliedebrauwer-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 man4/mem.4 | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/man4/mem.4 b/man4/mem.4
index 74b7b89..fef007e 100644
--- a/man4/mem.4
+++ b/man4/mem.4
@@ -54,7 +54,9 @@ is the same as
 .BR mem ,
 except that the kernel virtual memory
 rather than physical memory is accessed.
+Since 2.6.26, this file is only available if the
+.B CONFIG_DEVKMEM
+kernel configuration option is enabled.
 .LP
 It is typically created by:
 .RS
-- 
2.1.3

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[PATCH 2/3] mem.4: correct /dev/port group in example

[Elie De Brauwer]

mem.4 mentions that group for /dev/port should be set to 'mem' however
all other files (/dev/mem and /dev/kmem) use the kmem group in their
examples and on my system /dev/port belongs to kmem. Hence the 'mem'
group was probably a typo:

edb@lapelidb:~$ cat /etc/group | grep -i mem
kmem:x:15:
edb@lapelidb:~$ ls -al /dev/port
crw-r----- 1 root kmem 1, 4 Jan  2 10:00 /dev/port

Signed-off-by: Elie De Brauwer <eliedebrauwer-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 man4/mem.4 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/man4/mem.4 b/man4/mem.4
index fef007e..6688345 100644
--- a/man4/mem.4
+++ b/man4/mem.4
@@ -76,7 +76,7 @@ It is typically created by:
 .sp
 mknod \-m 660 /dev/port c 1 4
 .br
-chown root:mem /dev/port
+chown root:kmem /dev/port
 .RE
 .SH FILES
 .I /dev/mem
-- 
2.1.3

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[PATCH 3/3] mem.4: Add CONFIG_STRICT_DEVMEM

[Elie De Brauwer]

Since 2.6.26 the CONFIG_NONPROMISC_DEVMEM options limits the physical
addresses which can be accessed through /dev/mem.

Sources:
 - Changelog: http://kernelnewbies.org/Linux_2_6_26
 - Initial commit: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=ae531c26c5c2a28ca1b35a75b39b3b256850f2c8
 - Rename of name: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=d092633bff3b19faffc480fe9810805e7792a029

Signed-off-by: Elie De Brauwer <eliedebrauwer-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 man4/mem.4 | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/man4/mem.4 b/man4/mem.4
index 6688345..372d4fa 100644
--- a/man4/mem.4
+++ b/man4/mem.4
@@ -23,7 +23,7 @@
 .\" %%%LICENSE_END
 .\"
 .\" Modified Sat Jul 24 16:59:10 1993 by Rik Faith (faith-+5Oa3zvhR2o3uPMLIKxrzw@public.gmane.org)
-.TH MEM 4 1992-11-21 "Linux" "Linux Programmer's Manual"
+.TH MEM 4 2015-01-02 "Linux" "Linux Programmer's Manual"
 .SH NAME
 mem, kmem, port \- system memory, kernel memory and system ports
 .SH DESCRIPTION
@@ -40,6 +40,13 @@ References to nonexistent locations cause errors to be returned.
 Examining and patching is likely to lead to unexpected results
 when read-only or write-only bits are present.
 .LP
+Since 2.6.26, and depending on the architecture, the
+.B CONFIG_STRICT_DEVMEM
+kernel configuration option limits the areas
+which can be accessed through this file.
+For example: on x86, RAM access is not allowed but accessing
+memory-mapped PCI regions is.
+.LP
 It is typically created by:
 .RS
 .sp
-- 
2.1.3

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Re: [PATCH 1/3] mem.4: /dev/kmem depends on CONFIG_DEVKMEM

[Michael Kerrisk (man-pages)]

On 01/02/2015 02:11 PM, Elie De Brauwer wrote:
> Since 2.6.26 /dev/kmem depends on the CONFIG_DEVKMEM to be set.

Thanks, Elie. Applied.  

Cheers,

Michael


> See:
>  - changelog: http://kernelnewbies.org/Linux_2_6_26
>  - commit: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=b781ecb6a379f155568ef7093e38c6c1d857fe53
> 
> Signed-off-by: Elie De Brauwer <eliedebrauwer-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>  man4/mem.4 | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/man4/mem.4 b/man4/mem.4
> index 74b7b89..fef007e 100644
> --- a/man4/mem.4
> +++ b/man4/mem.4
> @@ -54,7 +54,9 @@ is the same as
>  .BR mem ,
>  except that the kernel virtual memory
>  rather than physical memory is accessed.
> +Since 2.6.26, this file is only available if the
> +.B CONFIG_DEVKMEM
> +kernel configuration option is enabled.
>  .LP
>  It is typically created by:
>  .RS
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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Re: [PATCH 2/3] mem.4: correct /dev/port group in example

[Michael Kerrisk (man-pages)]

On 01/02/2015 02:11 PM, Elie De Brauwer wrote:
> mem.4 mentions that group for /dev/port should be set to 'mem' however
> all other files (/dev/mem and /dev/kmem) use the kmem group in their
> examples and on my system /dev/port belongs to kmem. Hence the 'mem'
> group was probably a typo:

Sounds reasonable to me. Patch Applied. Thanks, Elie.

Cheers,

Michael



> edb@lapelidb:~$ cat /etc/group | grep -i mem
> kmem:x:15:
> edb@lapelidb:~$ ls -al /dev/port
> crw-r----- 1 root kmem 1, 4 Jan  2 10:00 /dev/port
> 
> Signed-off-by: Elie De Brauwer <eliedebrauwer-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>  man4/mem.4 | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/man4/mem.4 b/man4/mem.4
> index fef007e..6688345 100644
> --- a/man4/mem.4
> +++ b/man4/mem.4
> @@ -76,7 +76,7 @@ It is typically created by:
>  .sp
>  mknod \-m 660 /dev/port c 1 4
>  .br
> -chown root:mem /dev/port
> +chown root:kmem /dev/port
>  .RE
>  .SH FILES
>  .I /dev/mem
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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Re: [PATCH 3/3] mem.4: Add CONFIG_STRICT_DEVMEM

[Michael Kerrisk (man-pages)]

On 01/02/2015 02:11 PM, Elie De Brauwer wrote:
> Since 2.6.26 the CONFIG_NONPROMISC_DEVMEM options limits the physical
> addresses which can be accessed through /dev/mem.

Thanks, Elie. Applied.

Cheers,

Michael


> Sources:
>  - Changelog: http://kernelnewbies.org/Linux_2_6_26
>  - Initial commit: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=ae531c26c5c2a28ca1b35a75b39b3b256850f2c8
>  - Rename of name: http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=d092633bff3b19faffc480fe9810805e7792a029
> 
> Signed-off-by: Elie De Brauwer <eliedebrauwer-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>  man4/mem.4 | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/man4/mem.4 b/man4/mem.4
> index 6688345..372d4fa 100644
> --- a/man4/mem.4
> +++ b/man4/mem.4
> @@ -23,7 +23,7 @@
>  .\" %%%LICENSE_END
>  .\"
>  .\" Modified Sat Jul 24 16:59:10 1993 by Rik Faith (faith-+5Oa3zvhR2o3uPMLIKxrzw@public.gmane.org)
> -.TH MEM 4 1992-11-21 "Linux" "Linux Programmer's Manual"
> +.TH MEM 4 2015-01-02 "Linux" "Linux Programmer's Manual"
>  .SH NAME
>  mem, kmem, port \- system memory, kernel memory and system ports
>  .SH DESCRIPTION
> @@ -40,6 +40,13 @@ References to nonexistent locations cause errors to be returned.
>  Examining and patching is likely to lead to unexpected results
>  when read-only or write-only bits are present.
>  .LP
> +Since 2.6.26, and depending on the architecture, the
> +.B CONFIG_STRICT_DEVMEM
> +kernel configuration option limits the areas
> +which can be accessed through this file.
> +For example: on x86, RAM access is not allowed but accessing
> +memory-mapped PCI regions is.
> +.LP
>  It is typically created by:
>  .RS
>  .sp
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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