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I use xen with a buildroot on the CPU0 and a baremetal written in C on the CPU1. The arch is ARM64. The shared mem works with 1k of pages (an array of 4096 values). I am trying to send data from the ...
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I have a Ubuntu 24.04.2 system where /dev/shm gets remounted (I assume) every now and then (roughly each 10 seconds), but I have no idea why. There's no mention of that mounting point in /etc/fstab ...
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I'm interested in writing a program that can create two files, second file would be a "view" of first file and if modified, the first file would also be modified. Is this possible to do with ...
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I'm curious because today the only way I know how to give two different processes the same shared-memory is through a memory-mapped file, in other words, both processes open the same memory-mapped ...
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I am trying to figure out what will happen if I use the IPC_CREAT flag with shmget(). I have used a key of an already created shared memory segment from another process. When I did so, the calling ...
Ahmed Mohamed's user avatar
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Using shmget(), we can allocate a shared memory block of certain size in bytes and using shmat(), we attach this shared memory block to the address space of the calling process. I need to check my ...
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I am attempting to use a USB GPS without PPS dongle as the sole time source on Ubuntu 18.04. GPSD appears to be working correctly since cgps reports a 3D fix. However, I can't get chrony to see the ...
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Using Manjaro / Arch linux, I wanted to install another browser. However, no matter whether I installed Opera or Chromium (via pacman) I always get an error when executing it (from both Application ...
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According to my understanding about shared memory is that it is a memory segment that is shared between two or more processes. Shared memory can be implemented using shmget() . However , since any ...
AAA's user avatar
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Let's say, we are creating a shared memory using mmap(). Let's say the total memory size is 4096. If we use a fork() system call to create children, would the children use the same memory, or will ...
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as per the documentaion:- If SHM_RDONLY is specified in shmflg, the segment is attached for reading and the process must have read permission for the segment. Otherwise the segment is attached for ...
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I have written a "device driver" (see source code here: https://bitbucket.org/wothke/websid/src/master/raspi/websid_module/ ) that runs fine for most of the time (see https://www.youtube.com/...
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Issue: I have an FFmpeg command that I've been running for months now to stream video into the /dev/shm directory. It had been working fine until relatively recently (e.g. within a week), now it ...
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In Linux, when using mmap() for anonymous memory mapping, or using malloc(), do they allocate "space" from only physical memory, or either physical memory or swap or their combination? (I ...
Tim's user avatar
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Is there any way to revoke write permissions to shared memory by the process who created that shared object, s.t. any other process who has mapped the shared memory to its virtual space with write ...
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Here is a simple experiment I tried: Given a task called "sim.exe" which doing a model simulation, I then use MPI to launch x "sim.exe" simultaneously on one node (shared memory system). I have tried ...
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Are sharing a memory-mapped file and sharing a memory region implemented based on each other? The following two quotes seem to say so, and seem a chicken-egg problem to me. Operating System Concepts ...
Tim's user avatar
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Context: I am using POSIX shared memory to provide a set of processes with a shared memory space. I have used this scheme for some time now in order to share data, and it's working okay. However, I ...
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I have two processes sharing memory (via Boost Interprocess). Each process is run under a different user. The first process is run from one of our privileged users. The second process is ran via a ...
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When I run ipcs -m, I can see a list of the shared memory segments on the system, like ------ Shared Memory Segments -------- key shmid owner perms bytes nattch status ...
John's user avatar
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If file descriptors are specific to each process (i.e. two processes may use the same file descriptor id to refer to different open files) then how is it possible to share transfer file descriptors (e....
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Actually I would like to know the issues caused by independent concurrent writes to shared memory. To be more elobarote, consider we have three processes (proc1, proc2, proc3). These 3 processes are ...
Karthick's user avatar
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OS: Ubuntu 16.04 free output indicated about 2GB of shared memory. The shared memory was still allocated after a logout, and no particular process from top list was occupying it. ipcs -m did not ...
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I'm just wondering where these values are being set and what they default to? Mine is currently 18446744073692774399. I didn't set it anywhere that I can see. $ cat /proc/sys/kernel/shmmax ...
Evan Carroll's user avatar
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Not sure if the question is pertinent for this forum. We have a server with 3 apache instances running with the "same" app/functional ID These instances communicate with their corresponding ...
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