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Questions tagged [virtual-address-space]

virtual address space (VAS) or address space is the set of ranges of virtual addresses that an operating system makes available to a process

A virtual address does not represent the actual physical location of an object in memory; instead, the system maintains a page table for each process, which is an internal data structure used to translate virtual addresses into their corresponding physical addresses. Each time a thread references an address, the system translates the virtual address to a physical address.

A virtual address space (VAS) or address space is the set of ranges of virtual addresses that an operating system makes available to a process.[1] The range of virtual addresses usually starts at a low address and can extend to the highest address allowed by the computer's instruction set architecture. This provides several benefits, one of which is, if each process is given a separate address space, security through process isolation.

http://en.wikipedia.org/wiki/Virtual_address_space
http://msdn.microsoft.com/en-us/library/windows/desktop/aa366912(v=vs.85).aspx

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How 4gb(VM) Address space used while swithcing from/to user space to kernel space

I looked at a lot if online thread/tutorials regarding how process address space is divided into process/kernel Ex: i have some Helloworld program in that i have call as printf(in turn it makes write system call to enter into kernel space) My doubt…
Amarender
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Virtual Address of process in Linux64/x86_64 machine

I have two questions related to the Process Address map; I know in the 32 bit Linux machine, the virtual address of a process is divided into two, 3GB for Userspace and 1 GB for Krnel. Is it the same for x86_64/Linux 64 machine? The objdump of a…
Franc
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zero sized heap memory in page aligned allocation`

I'm trying to study how Linux would behave if I were to allocate a 10 bytes of memory at every page boundary for a total of ten pages. Here is the program I could come up with: 1 #include $ 2 #include $ 3 #include $ …
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How do correlate symbol information from PDB with PE contents?

I've been trying to get a better understanding of where my C++ source code ends up in a PE format and how to find specific points in my source code in the PE. For example, I have a simple program which I've compiled with /Od and /ZI flags. There's…
Joe
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Does a segmentation fault in gdb show the physical or virtual address?

I tried to smash the stack: int main (void) { int ar[5] = {1,2,3,4,5}; for(int i =0; i<255 ; i++) ar[i] = 10; return 0; } with gcc -fno-stack-protector somefile.c. First question: why is there difference with fault with…
Herdsman
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Converting from a virtual address space to a physical address spae

This topic has been somewhat covered in other posts, but in my example I need to find more than what is shown on the other examples, and I struggle to clearly understand what exactly is going on. Suppose I have the following system properties (and…
NewDev90
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How are the sizes of pointers determined in computer systems? Via virtual or physical addresses?

I have an exam tomorrow on virtual memory address translation and I'm rather confused on this topic. I know the CPU will generate a virtual address to then access a physical address. So if we have a system with 32 bit virtual addresses, and 64 bit…
1010lll
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How can two virtual memory pointing to same physical memory in linux

i was reading a page that told: "My microbenchmark begins by allocating one memory page, then creates two virtual address aliases pointing to it" First Question. i want to know how can i create two virtual address that pointing to same memory page…
alireza sadeghpour
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Create App Service Environment Subnet address space issue

I am trying to create a new Azure App Service Environment within an existing virtual network that contains two address spaces. In this case I am trying to create the subnet in the second address space as shown below. When I then try to create a new…
Phil Murray
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Understanding Page Sizes

The problem states, "Physical memory consists of 64 bytes divided into pages of 16 bytes. Likewise, the virtual address space is also 64 bytes." It also states, " Each page table will be placed in its own page in the simulated memory [we are using…
JGerulskis
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How to map a userspace virtual address to another userspace virtual address through kernel module?

I'm writing a Linux kernel module. A userspace process (P1) sends a virtual address and size to my kernel module. I save the virtual address (V1). It corresponds to some physical address (Ph). Now, another userspace process (P2) calls my kernel…
soham
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How to inspect dumps with WinDBG that are out of Process Context, and get correct callstack

I have an crash issue with one of our customers, and I managed to acquire the logs with adplus -pmn utility, running in monitor mode so that it monitors the process during the crash. Once I inspected the dump, it shows me the following: WARNING:…
Loop
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Are memory segments defined by the OS or architecture?

The x86 architecture has segment registers for various segments of the address space (ss, ds, etc). If I wanted to add a new memory segment into a process address space, could I do it by just modifying the kernel or would I need hardware support?…
Carson Harmon
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Getting "Bad file descriptor" error when trying to mmap BAR-0 of device

I am trying to mmap BAR-0 of a PCI device to the virtual address space in order to read (and later modify) its contents. However when I mmap it, I get the following error: Path to BAR-0: /sys/bus/pci/devices/0000:00:16.0/resource0 Error at line 42,…
A.Z.
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How does a memory managemet unit map a virtual address to a physical address

If a computer system has a main memory of 1mb and virtual address space of 16mb while the disk block size is 1kb. How does the memory management unit map a virtual address to a physical address?
Redgren Grumbholdt
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