lkml.org 
[lkml]   [2008]   [Nov]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Turn CONFIG_STRICT_DEVMEM in sysctl dev.mem.restricted
On Sun, 16 Nov 2008 16:56:09 +0100
Bernhard Walle <bwalle@suse.de> wrote:

> > > While the original submission of CONFIG_STRICT_DEVMEM mentions
> > > that the option has been in RHEL and Fedora for 4 years without
> > > problems, that's only a half of the story. The truth is that at
> > > least RHEL has /dev/crash exactly to circumvent that /dev/mem
> > > restriction. Don't tell me that this is better than having that
> > > sysctl entry. ;-)
> >
> > I assume /dev/crash is read only
>
> I don't know. But if that matters, why can't we make /dev/mem
> write-only for certain areas and read-only for the rest ...?
>
> > You either want this at compile time or you don't want it at all.
>
> Why? You don't write something about my arguments (as Alan does, even
> though I disagree), you only write that you "nak" it.

It's very simple: if you want the strict form you really want the
strict form, not some half "oh but it's one line to turn off" form.


(Note: your usecase is in trouble in general already with PAT used by
modern video drivers: the requirement is that all mappings of the same
physical page are mapped with the same cachability semantics. mmaping
random parts of physical real memory via /dev/mem makes that a way too
complex issue and will likely turn the crash utility in what it's name
says ;-)

--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org


\
 
 \ /
  Last update: 2008-11-16 17:09    [W:0.040 / U:21.892 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site