03-03-2010
translating physical/virtual addresses
Hi all,
I am new to Linux kernel/user space programming having been an assembly programmer in my previous life. I am now using 2.6.x kernel on an embedded CPU that has a few dedicated hardware blocks (including more CPU running just C-code, i.e., no operating system).
There is a single DRAM connected to this chip with one Linux CPU + multiple h/w blocks. No swapping since this is being done for an embedded device (SoC ASIC chip with a single 32-bit DDR2 interface, no hard-drive).
Question(s):
1. The Linux CPU needs to talk to hardware blocks that obviously physical DRAM addresses while Linux processes/threads use virtual addresses.
2. How do I translate these addresses back-n-forth? For example, a Linux process may want to allocate memory and then hand it off to a hardware block to write into it. Then after a while the process will read it.
3. Sometimes, the hardware block may write a physical address into the shared memory. The Linux CPU will read the shared memory and then convert the physical address to virtual memory and go read that location.
How does one achieve all of this? If this is being extremely stupid, then please let me know. Hopefully, you can give me some pointers. A website, book, code, man page, high-level thoughts, anything would be appreciated.
Thanks a lot,
Guraaf
10 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
i am running solaris 9 i now how to create virtual ip address but how do i keep them so when the server reboots they are still there?...THANX (2 Replies)
Discussion started by: rmuhammad
2 Replies
2. Shell Programming and Scripting
What command can i use to get the physical and virtual memory of a database? (7 Replies)
Discussion started by: tads98
7 Replies
3. UNIX for Advanced & Expert Users
Hello,
I would like to know if there is a command or any configuration file to find and differentiate the Virtual IP Addresses (of the Cluster Resource Group) and the IP Address of the Cluster Node. I observe that the ifconfig -a command returns all the IP addresses configured on the ... (1 Reply)
Discussion started by: vineetd
1 Replies
4. IP Networking
How would i create virtual interface in linux to configure more than one IP address for a physical interface?
any help wll be appreciated.
https://www.unix.com/images/misc/progress.gif (1 Reply)
Discussion started by: salil2012
1 Replies
5. Solaris
Hi,
I am on an Solaris machine "SunOS 5.10 Generic_139556-08 i86pc i386 i86pc"..how do i check if I am on an physical or an virtaul server.
Thanks. (6 Replies)
Discussion started by: jjoy
6 Replies
6. Solaris
Hello,
Firstly, apologies if the theme of this post is discussed elsewhere.
At the moment we have a dual-domain M5000 running. Each domain is running with equal amounts of CPU and memory.
What we'd like to do is move the 2 hosts in question (1 per domain) to a Solaris 10 zone of it's zone.... (2 Replies)
Discussion started by: nm146332
2 Replies
7. UNIX for Advanced & Expert Users
Hi All,
How can I know whether the server I am connecting to is a virtual or physical one? The server might be having any Unix OS (Linux/Solaris/HP-UX etc.).
Is there any system files / commands which can show these concrete information?
Thanks in advance for the replies.
sanzee (1 Reply)
Discussion started by: sanzee007
1 Replies
8. Red Hat
Hi,
i am trying to find out hpw many virtual and physical processors does any linux machine has:
output of /proc/cpuinfo is as below :
# cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 26
model name : Intel(R) Xeon(R) CPU... (8 Replies)
Discussion started by: omkar.jadhav
8 Replies
9. AIX
HI,
I need a command to find,
1) Avaiable Physical CPU
2) Avaiable virtual CPU
TIA (1 Reply)
Discussion started by: sumanthupar
1 Replies
10. Solaris
uname -a reports type Generic so I know its virtual. Assume its an ldom somewhere.
How do I find out what physical host server is? (4 Replies)
Discussion started by: psychocandy
4 Replies
PHYS(2) System Calls Manual PHYS(2)
NAME
phys - allow a process to access physical addresses
SYNOPSIS
phys(segreg, size, physadr)
DESCRIPTION
The argument segreg specifies a process virtual (data-space) address range of 8K bytes starting at virtual address segregx8K bytes. This
address range is mapped into physical address physadrx64 bytes. Only the first sizex64 bytes of this mapping is addressable. If size is
zero, any previous mapping of this virtual address range is nullified. For example, the call
phys(6, 1, 0177775);
will map virtual addresses 0160000-0160077 into physical addresses 017777500-017777577. In particular, virtual address 0160060 is the
PDP-11 console located at physical address 017777560.
This call may only be executed by the super-user.
SEE ALSO
PDP-11 segmentation hardware
DIAGNOSTICS
The function value zero is returned if the physical mapping is in effect. The value -1 is returned if not super-user, if segreg is not in
the range 0-7, if size is not in the range 0-127, or if the specified segreg is already used for other than a previous call to phys.
BUGS
This system call is obviously very machine dependent and very dangerous. This system call is not considered a permanent part of the sys-
tem.
ASSEMBLER
(phys = 52.)
sys phys; segreg; size; physadr
PDP11 PHYS(2)