General :: Virtual Memory Address To Physical Address?
Apr 13, 2010How can I get the physical address corresponding to a virtual address in linux by using /proc file system
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General :: Virtual Address To Physical Memory Access ?
Feb 21, 2010A process is trying one access to memory, for example through an array (ex.: vect[0]=123. What happens?
Here below what I guess but I'm not sure and accept any comment (please, distinguish between "the system" and "the CPU" in case).
Let's suppose swapping to disk disbled.
We have two scenarios: without and with cache.
If no cache is present in the system:
1. The CPU must discover the phys addr of vect[0] virtual addr. To do that, has to read from 3 (or 2 depending on the system?) pages tables, stored in memory as well.
2. The CPU writes to the final address.
These mean 4 memory accesses.
If cache is present:
1. Like above but, if the pages tables are in cache, we have 3 accesses to that.
2. If the req. page is not in cache, it's reads from ram and transferred to it. Afterwards, cache is written.
In the best case we have 4 cache accesses.
General :: Mapping Kernel Virtual Address Space To Physical Memory Zones?
Nov 4, 2010As i undertsand - out of 1GB of the virtual Address space for Kernel from 3GB to 4GB of the process address space, Kernel image (code, data, bss, stack, heap) resides staring @0x0 address. Vmalloc area starts either at the end of Physical ram size or at 896M. This 896M cap is mandated to ensure that minimum of 128MB is reserved as vmalloc_reserve for vmalloc,kmap etc.
Is the understanding correct? Now trying to map Physical Zones into this 1GB address space
Initial 16MB is mapped to ZONE_DMA
16MB - 896MB is mapped to ZONE_NORMAL
896MB - 1024MB is mapped to ZONE_HIGHMEM
Does this mean that Kernel image is residing in ZONE_DMA area? Any call to vmalloc() in kernel code will return address beyond 896M? insmod of any LKM will internally invoke vmalloc() to obtain contiguous area - where will this code physically located along with rest of kernel code in ZONE_DMA or in ZONE_HIGHMEM?
Programming :: Access At Physical Address - I/O Address In My Map Memory?
Dec 17, 2008When I try to access at physical address (0xD0000), we known that it is necessary to convert physical address to virtual address using function IOREMAP(0xD0000, 1024) and return me 0xC00D0000.
Now our doubt is when I have a board with I/O in address 0x150, is it necessary to convert this address to other virtual address??? or with inb(0x150) return me state of I/O in this address? How can I known where is this I/O address in my map memory?
Programming :: Physical Versus Virtual Mac Address And Mac Address From NIC's Firmware?
Apr 6, 2011I need a small shell based program that prints the mac address of physical ethernet adapter from it's firmware. I need this utility for license generation and appliance activation. I have tried several example but none of them is flawless, The easiest method I have found is to parse the output of "ifconfig" command but it has also some drawbacks.
1. Firstly program should differentiate between physical and virtual adapters. Physical means installed on board(wired or wireless) or installed additionally. Virtual adapters are those created by VPN or created by virtualization apps such as VirtualBox/VMWare etc. I am not interested in virtual ones.
2. In case of more them one physical adapters(wired and wireless), it should print the mac address and description(name & vendor) of both/all adapters.
3. If media is disconnected then also it should be able to read the mac address and description(name, vendor) of card.
4. This one is bit complex. I know that 'ethtool' can show you the universal mac address but it's limited to use only 2 types of drivers and won't work in all cases.
Programming :: Translate Virtual Address To Physical Address In Application?
Nov 18, 2009I want to translate the virtual address to physical address in linux C application, how to do that?
View 1 Replies View RelatedGeneral :: Application Virtual Address Space Memory Allocation - Memory Does Not Get Free
Apr 20, 2010I am using malloc and frees a lot in my program. It shows its allocated but when i remove it doesnt show as the memory is removed(I am using the top command to view VIRT memory usage). If this continously grows what would happen to my program (Will it go out of memory?)
View 4 Replies View RelatedGeneral :: Use Where Save For The Physical Address Going Towards The MAC Address
Jul 19, 2010im REALLY new with linux and ive downloaded and installed Ubuntu...now heres the question.how do i set up WLAN internet use? ive tried using ipconfig/all on windows command but im not sure which info to use where save for the Physical Address going towards the MAC Address info
View 14 Replies View RelatedSoftware :: Physical And Virtual Address Differences?
Jul 15, 2010I am interested to know memory layout in linux os.What are the differences between physical address and virtual address?
View 1 Replies View RelatedProgramming :: Find Physical Address Of Memory Provided By Kmalloc
Oct 22, 2009I allocated a chunk of memory using kmalloc in a Device Driver. Kmalloc provides a pointer to the allocated memory. This is one of my first few drivers.
I assume that the address returned is a Virtual address. I need to find the physical address of the memory location. I am working on an Intel 64 bit Fedora machine. I used the virt_to_phys() routine present in <asm/io_64.h>. I found that this routine returns an unsigned long value (32 bit) instead of an unsigned long long value (64 bit). Moreover, it seems that it simply returns the address - OFFSET instead of extracting the value in the page tables.
So is there any function / system call in Linux which will allow me to see the actual physical address on the Intel 64 arch.
Programming :: Shared Memory Address Area In Process Address Space?
Feb 21, 2011if i attach a shared memory to my process whch part of the address space it will add(like stack, heap, data, code...).
View 3 Replies View RelatedGeneral :: Physical And Virtual Memory Upper Limit For 32 Bit?
Jun 26, 2010I have a 32 bit Ubuntu installed and my Laptop has 4GB RAM, but only 3GB is considered by Linux. My question is: what is the reason for the upper limit on physical memory ?
Code:
dmesg | grep Memory [0.000000] Memory: 3052428k/3112960k available (4673k kernel code, 56364k reserved, 2121k data, 656k init, 2200904k highmem) I am familiar with the virtual memory concept where linux splits upper 1GB for kernel and lower 3GB for user processes. In total, linux 32bit can address 4GB virtual addresses. Does this meant that 1GB of physical memory is already mapped to 1GB of kernel space and Linux only shows the remaining 3GB physical memory left for the user in the above command.
I did some searching on the internet and found some articles related to this, but it only confused me further since some articles suggest 4GB is the upper limit with mentioning whether it's virtual or physical memory, some bring in the concept of PAE, etc. I'm relative new to Linux's memory management, so it'd be really helpful if someone could answer this.
General :: How To Read/write Physical Address
May 17, 2010One of the tasks I want to do is to read/write from/to any physical address. My question is how do I get a physical address on my Linux desktop. I was thinking of using some utility to dump my BIOS settings, and modify a "not so important" memory address there? Is this possible. Otherwise is there any other physical address I can read/write
View 3 Replies View RelatedProgramming :: Get The Page Pointer From A Physical Address?
Oct 18, 2010How do I get the page pointer from a physical address?
View 1 Replies View RelatedUbuntu Networking :: Physical Address For Ethernet Adapter?
Aug 26, 2010I've just arrived at uni and to set up my wifi apparently I need my "media access control which is listed as the phsyical address for ethernet adaptor local area connection." on windows you can find it by using the command ipconfig /all but that didn't work when i put it into terminal.
View 1 Replies View RelatedSoftware :: Accessing Memory Address Outside Standard Memory
Nov 22, 2009I am writing an application that wants to access periphals registers outside the standard (allowed) memory area.
Doing so gets me "segmentation fault".
I know, this is natural behaviour.
One way of getting around this is writing the module which has to be loaded by linux. I will consider this some time later.
For now, I want to come to some quick result and allow linux or gcc compiler to write to those memory areas of periphals. Is there a direct way to do so?
General :: System Do Fragmentation On Virtual Address Space?
Apr 21, 2010I have millions of small chunks of new's and delete's in my program. Even though no memory leak is detected through valgrind or purify, memory grows. But the growth is degrading over the number of times of the execution of the tasks. Can i think that fragmentation plays a role in this?
View 6 Replies View RelatedGeneral :: Finding The Memory Address(in FLASH) Of A Command In Shell Script?
Mar 29, 2011If i have a shell script to run on a Linux unit, which has a command to Reset(or say upgrade) the unit in between the script.Is it possible to find out the memory address of the next waiting command so that i can store the address to any environment variable in flash , then after Reset will continue Run from the stored address.
View 3 Replies View RelatedProgramming :: Print Physical Address Of Page Directories For All Processes?
Apr 4, 2011How to printing physical address of page directories for all processes?
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
[code]....
General :: What Is Production IP Address And Management IP Address In Servers
Jul 20, 2011what is Production IP address and Management IP address in Linux servers? What is the significance of these two? When to use what?
View 3 Replies View RelatedNetworking :: Outgoing Local Trafic Over Virtual Interface Has Not Virtual Ip Address
Aug 25, 2009When I create virtual ethernet interface and do a ping -I <v_int> <host> the outgoing address is the one of the physical interface and NOT the virtual interface.Is there no chance that trafic will go out with virtual interface address??Incoming trafic is done well i.e. responds to the virtual interface have the virtual address.
My problem is that I have 2 modems and want to check both default gw behind the modems.
If I do a "normal" ping both are reachable over default route even the modem which is not the default route will not work because ping goes over the working modem.So I have 2 routing tables and want to route the virtual interface to one modem the other to the other modem
General :: Can't Statically Decide Virtual Address Of The Function At Compile Time?
Feb 8, 2010I have read a couple of articles on how dynamic linking works (those stuff about got, plt and lazy binding), and I am still not sure why you need to do dynamic linking in such a complicated way.Suppose your program uses a function in a shared library that needs to be linked dynamically at run time (like a printf). Why can't you statically decide the virtual address of the function at compile time? After all, all you need to do is to enter the page table entry corresponding to the address of the function if the library has been already loaded to a physical page frame.
View 3 Replies View RelatedGeneral :: Postfix Error: Address Not Found In Virtual Alias Table
Sep 8, 2010I setup a virtual server with these configurations:
1. Mail server: POSTFIX / DOVECOT
2. Webmin / Virtualmin
I am getting email to desired folders locally but I am not getting email from outside to desired users. Emails are bounced back with message "Address not found in virtual alias table".
Recent log errors are:
Sep 8 04:25:49 server1 postfix/smtpd[28002]: cannot load Certificate Authority data
Sep 8 04:25:49 server1 postfix/smtpd[28002]: warning: TLS library problem: 28002:error:02001002:system library:fopen:No such file or directory:bss_file.c:122:fopen('/etc/pki/postfix/root.crt','r'):
[code].....
General :: Setup Virtual Machines To Be Servers With Bind Option Set To A Multicast Group Address Of 225.0.62.87?
Mar 28, 2010I am in verse to test "Multicast Packet filtering".I want to setup Virtual Machines to be servers with bind option set to a multicast group address of 225.0.62.87.Then I want to configure the client VM, connecting to the multicast group address and setting the TTL as needed.
View 3 Replies View RelatedProgramming :: Shared Memory - Should They Show The Same Address?
Mar 17, 2010So I'll try to be brief and to the point here: I've got a couple of C / C++ apps that communicate with one another via shared memory. These worked completely fine until.. well, about twenty minutes ago when I finished making some network card changes and suddenly, I've got a weird problem going on. At one point, Parent app waits for Child app to set a boolean indicating it's finished initialization. This worked fine the last time I ran this app up (a few days ago). But right now, the shared flag never seems to get triggered (I've added a printf("Waiting..."); in Parent app until the flag is set). All the code leading up to it being set in Child app seem to be running smoothly, so I tried spitting out the addresses of the shared memory locations. The addresses mapped by Parent app and Child app are different; this seemed odd, so I went back and wrote a simple miniature app that just opened a shared structure on my own box, and I get the same thing - different addresses - but the miniature apps work just fine.
Is it normal for a shared memory space to be mapped to two different addresses across two processes?
If so, does anyone have any idea what might be the issue at hand with my Parent / Child app scenario? The Child creates the shared memory, the Parent has a wait before it opens it, and if it doesn't exist should fail (opening with PROT_READ | PROT_WRITE)... it doesn't fail so it's evidently there.
All of this worked until literally just a few hours ago and I made some changes to my network cards, and I can't even imagine how that could have changed whether or not shared memory mapping worked...
Programming :: Gdb Reports - Cannot Access Memory At Address 0x8049088
Jul 11, 2011Kernel 2.6.21.5, slackware 12.0
nasm 2.03.01
ld 2.17
GNU gdb 6.6
This GDB was configured as "i486-slackware-linux".
Code:
What could the cause of the message output by gdb possibly be? Reading some tutorials, I've learn the flat memory model is used in linux. So, in particular, I needn't care about the DS segment register.
Also, line 7 in the listing above, suggests nasm is assuming 32-bit addressing and so, I think it is using the flat memory model.
Programming :: Calculate Flash Memory End Address Of A Certain File?
Mar 9, 2011how to calculate (if possible) the end address of an image file in a flash memory. I'm trying to create a checksum and checkheader function and the info that I got is the file's offset, how many sector it consumes and its size. I kinda need the end address, sad thing is, I don't know how to calculate it.test.img's start address is 0, the size is 0x20000 and consumes 3 sectors.
View 6 Replies View RelatedProgramming :: Seg Fault. Memory Address Not Being Passed To Function?
Apr 19, 2010I am writing a game in C with SDL. I can successfully display one image on the screen and animate it. However, I am having a lot of issues getting the background to display using the same method. I was asking for help on SDL related forums, but I determined that the issue is not SDL related, and it is actually a pointer issue. However, I can't find where I'm going wrong.
Code:
#include <SDL/SDL.h>
struct image
[code]...
Security :: Address Space Randomization On 2.6.28-15-generic Ubuntu 9.04 - Finding Base Address?
Sep 14, 2009Im an academic (university networks and security lecturer) studying/teaching network and operating system security, and inspired by the work of Hovav Shacham set about testing ASLR on linux. Principley I did this by performing a brute force buffer overflow attack on Fedora 10 and Ubuntu 9. I did this by writting a little concurrent server daemon which accidently on purpose didnt do bounds checking.
I then wrote a client to send it a malicious string brute forcing guessed addresses which caused a return-to-libc to the function usleep with a parameter of 16m causing a delay of 16 seconds as laid out in [URL] Once I hit the delay I new I had found the function and could calculate delta_mmap allowing me to create a standard chained ret-to-libc attack. All of that works fine. However .... To complete my understanding I am trying establish where I can find the standard base address for ubuntu 9 (and other distros) for the following, taken from Shacham:-
Quote:
[code]....
/proc/uid/maps gives me some information but not the base address ldd also gives me the randomised starting address for sections in the user address space but neither gives me the base address. Intrestingly ... when a run ldd with aslr on for over (about) 100 times and checked the start point of libc I determined that the last 3 (least significant) hex digits were always 0's and the fist 4 (most significant) where between 0xB7D7 and 0xB7F9. To me this indicated that bits 22-31 were fixed and bits 12-21 were randomized with bits 11-0 fixed. Although even that doesnt define the boundaries observed correctly.
Note: I am replicating the attack to provide signatures to detect it using IDS, and for teaching purposes. I am NOT a hacker and if needed to could reply from my .ac.uk email address as verification.
Ubuntu Networking :: Port Forwarding From Public Address To Private Address?
Feb 24, 2010Currently my OS is Ubuntu 9.04 Jaunty Jackalope Desktop OS and my web server is Apache2. I have a public address 60.x.y.z and my pc local address is 10.x.y.z. I have a web app in my Apache2 which currently run in localhost(10.x.y.z).
I would like to enable the web app so that it could be browse from outside. I know there maybe some port forwarding process and some commands involved in order to do that. But I have no idea on the steps to do that.