From: Matt Porter <mporter@kernel.crashing.org>
To: Oliver King-Smith <oliver.king-smith@nuvation.com>
Cc: "'linuxppc-embedded@lists.linuxppc.org'"
<linuxppc-embedded@lists.linuxppc.org>
Subject: Re: Problem trying to address custom hardware
Date: Wed, 25 Aug 2004 16:05:25 -0700 [thread overview]
Message-ID: <20040825160525.F9986@home.com> (raw)
In-Reply-To: <FC3C0DD86B79DF4FA423AF0379A5476101554372@mailguy2.nuvation.com>; from oliver.king-smith@nuvation.com on Wed, Aug 25, 2004 at 03:29:20PM -0700
On Wed, Aug 25, 2004 at 03:29:20PM -0700, Oliver King-Smith wrote:
>
> Things are working much better. Both the driver and the main code work
> without crashing now.
>
> > Others addressed your core problem, but you should know that this
> > mmap request won't produce the desired result. You need MAP_SHARED
> > since MAP_PRIVATE will result in a COW when you attempt to modify
> > your register.
>
> I am not sure I understand why this needs to be MAP_SHARED (it sure does
> though). Is there a good resource I can read to understand this a bit
> better?
The mmap(2) manpage explains the difference pretty well. MAP_PRIVATE
indicates that any modification are local to the process. So, as
soon as you write to it, it makes a copy of the page for your process
to modify. MAP_SHARED indicates that any modifications are seen by
any processes that also map the region.
googling will probably yield many threads on lkml on this topic.
-Matt
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2004-08-25 23:05 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-08-25 22:29 Problem trying to address custom hardware Oliver King-Smith
2004-08-25 23:05 ` Matt Porter [this message]
-- strict thread matches above, loose matches on Subject: below --
2004-08-25 7:50 Rupesh S
2004-08-24 23:10 Oliver King-Smith
2004-08-25 5:56 ` Eugene Surovegin
2004-08-25 17:40 ` Matt Porter
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20040825160525.F9986@home.com \
--to=mporter@kernel.crashing.org \
--cc=linuxppc-embedded@lists.linuxppc.org \
--cc=oliver.king-smith@nuvation.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.