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Questions tagged [dma]

Direct memory access (DMA) is a feature of modern computers and microprocessors that allows certain hardware subsystems within the computer to access system memory for reading and/or writing independently of the central processing unit.

Direct memory access (DMA) is a feature of modern computers and microprocessors that allows certain hardware subsystems within the computer to access system memory for reading and/or writing independently of the central processing unit.

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How can I read from the pinned (lock-page) RAM, and not from the CPU cache (use DMA zero-copy with GPU)?

If I use DMA for RAM <-> GPU on CUDA C++, How can I be sure that the memory will be read from the pinned (lock-page) RAM, and not from the CPU cache? After all, with DMA, the CPU does not know anything about the fact that someone changed the memory…
Alex
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How to make a dynamic string?`I want to get a string dynamically but i don;t what to use it like this: string = (char*)malloc(100 * sizeof(char));

#include #include int main() { char string[100]; printf("Enter string: "); fgets(string, 100, stdin); return 0; } Or we can also do something like this: char **string; string = (char **)malloc(100 *…
Manvi Koul
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rp2040 DMA channel hung, baremetal

I'm trying to trigger a DMA channel to perform a memory-to-memory transfer within the SRAM. The channel throws up the busy flag, but there is no change to the transfer count. I have the following code: ;reset dma ldr r0, *resets_clr ;clear…
Will Thomas
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How does DMA work? What is the workflow of DMA?

I am trying to learn the basics of DMA. I watched certain videos on YouTube for the same. I have got a few queries: Can we set/reset bits of registers using DMA? Like if I want to set the 4th bit of GPIO_ODR, can I do it using DMA? Does DMA follow…
Aditya Ubarhande
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How fast can I read an ADC of a 2-dimensional array?

I have an application where it must control the ADC reading of the array 32x32 element. For each element I have to choose point - read ADC - turn off ADC. Currently I am using a scanning method like LED scanning. For each scan I read 1 point. Then…
Phạm Chiến Trung
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DMA1 Does not Work With USART1 in stm32f103c8?

I'm Trying to enable DMA1 with USART1 in stm32f103c8 but it does not work . i enabled the usart to work as transmitter . and then enabled the DMA1 and make this configuration to it 1-enable the DMA1 clock from RCC. 2-disabled the DMA1 Channel…
Hesham Adel
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KMDF DMA transfer slows down after a few restarts

Story: I am developing a KMDF driver for a custom PCI-E board, which has a PLX9056 chip connecting to the PCI-E. The driver and it's test software works perfectly after booting the computer, but after restarting the software and driver a several…
jakab
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Byte I/O with DMA, what's the advantage?

I have a A/D where signals CPU whenever it has new sample, and CPU reads that through a SPI, which is few bytes. My question is, can we use DMA here? Who and how should tell DMA to transfer new data? Does it make sense to use DMA? This is basically…
doubleE
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Books for programming processors/microcontollers using DMA, interrupts

I'm looking for a book for processors programming using DMA, interrupts. It may be for beginner, with full guide to using all processor's peripherial with examples. I have to use a processor with a core Cortex-M0, but books may be for Cortex-M3 and…
Ilya A
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HAL SPI DMA check how many bytes received during operation

I am transferring 10 bytes from master to slave over SPI+DMA with HAL. How can I check whether how many bytes the receiver has at that moment and if all the 10 byte has not been received then stops the process again. Because the master after sending…
Aashram
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How a pc host issue long pcie read/write burst to my device?

I have a pcie board with a segment of memory which is mapped to system address space. The memory controller can accept long burst read or write request. In the host program, when I use for loop to read or write the memory, will the host generate…
Chao Xiang
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Does network stack on my computer use DMA?

I learned that harddisk data is transferred to main memory using DMA, but network stack data cannot use DMA and the data has to go through processor. Is it true? If yes, what are the ways to avoid this? Isn't it really inefficient to transfer data…
Boolean
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STM32F429 GPIO DMA Read and Write

Hello, I'm making a project where I want to bit-bang the JTAG protocol. According to the AN4666 provided by ST, DMA + GPIO can achieve high speeds in bit-banging synchronous protocols. I want to: Generate N PWM pulses (the CLK signal). With the…
Samer Sadek
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How application memory is freed in operating systems?

I was going through the common issues in memory management. I'm curious to know how is the memory managed in the following case with dynamic memory management in c: I request the memory manager to provide me a free portion through malloc() call. I…
Surya Bhusal
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what's the point of DMA proxy. Or can we use kernel data structures in userspace which makes no sense

I was studying DMA proxy and DMA proxy channels. Basically they are like letting Userspace application to write tx, read rx kernel data-structures. and let the device to access virtual memory data structures since devices understand physical…
Ti1
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