From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S268421AbUJDF3i (ORCPT ); Mon, 4 Oct 2004 01:29:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268409AbUJDF3g (ORCPT ); Mon, 4 Oct 2004 01:29:36 -0400 Received: from web52903.mail.yahoo.com ([206.190.39.180]:20871 "HELO web52903.mail.yahoo.com") by vger.kernel.org with SMTP id S268411AbUJDF30 (ORCPT ); Mon, 4 Oct 2004 01:29:26 -0400 Message-ID: <20041004052926.79727.qmail@web52903.mail.yahoo.com> Date: Mon, 4 Oct 2004 06:29:26 +0100 (BST) From: Ankit Jain Subject: Re: Accessing memory with /dev/port To: jonathan@jonmasters.org In-Reply-To: <35fb2e5904100219381fe06db9@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org hi -- Jon Masters wrote: > On Sun, 3 Oct 2004 01:17:22 +0900, aq > wrote: > > > I heard that it is possible to modify the kernel > memory via some > > special devices like /dev/mem, /dev/kmem, > /dev/port and /dev/kcore. > > There are some papers about that techniques > concerning /dev/mem and > > /dev/kmem, but I cannot find any information > explaining how to do that > > (access and modify the memory of kernel) with > /dev/port and > > /dev/kcore. > > > > Anybody knows about these methods, please tell me? > > The best thing to do is to consult the documentation > for mmap and then can u tell some place where i can go look for this mmap. i had seen some places but the concepts are theoretical. how to do things are nto told much > experiment with mapping these devices and making > changes to the mapped > memory (make sure you perform any accesses to device > memory using > volatile keywords in your pointer declarations). > However I'd be really > very concerned if you want to actually modify kernel > memory this way. well i would like to see if the kernel memory can be increased or in some way i can understand these concepts(do u know any document or link) > > The best way to send information to or from the > kernel is to use a > file in /proc and use conventional read/write file > operations upon it. > The is the way we do things in UNIX. i want to know what is this file used for /proc/kcore > > Having said that, there can be times when mapping > the raw memory is > useful - if for example you want to display the > contents of various > bits of kernel data structures. I'm mulling the idea > of writing a GUI > tool to visualise bits of kernel data graphically - > I'm not bothered > by keeping it all in sync and up to date, just a > view. I bet it's been > done. > well my system is having all this 128 Mb Ram and redhat linux 9.0 kernel 2.4 now i see even on system with 512 Mb RAM the most of the ram is occupied by GUI or xserver around 90% of memory there is no way to reduce this load? i want to tune it for better performance and i also want GUI thanks Ankit ________________________________________________________________________ Yahoo! Messenger - Communicate instantly..."Ping" your friends today! Download Messenger Now http://uk.messenger.yahoo.com/download/index.html