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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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Is Linux kernel aware of which instruction is DMA related?

I have this problem related to the concept of Direct Memory Access (DMA). Does the OS/Linux Kernel have some ways to know which instruction is using DMA and which doesn't? Or the DMA is completely implemented by hardware and OS has no access to the…
Junji Zhi
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SATA in Samsung Exynos

Please take a look at the picture below. You can see that Samsung integrates SATA 3 into the Exynos 5 Dual. So does that mean that smartphones which use Exynos 5 will be able to connect to hard drives or optical drives by using SATA interface ? Do…
laituan245
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Using DMA to read EEPROM on SPI (SSP) Bus

I'm using an NXP LH79525, ARM7TDMI based processor. There is an EEPROM connected via SPI bus to the SSP port. The objective is to read the EEPROM into SRAM for faster accessing. The present working code sends a read command to the EEPROM, the…
Thomas Matthews
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How to trigger a DMA operation on PCI sound card

I'm a newbie to driver development in Linux. I want to trigger a DMA read operation at specified target address, but I have no basic concept about how to do it. Should I write a new driver for my sound card? Or just invoke some APIs(if any) provided…
qweruiop
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Linux memory manager infringes on PCI memory

My board has a Cavium Octeon NPU, running Linux kernel 2.6.34.10 that acts as a PCIe Root Complex. It is connected to PCIe switch, as are some other peripheral devices (Endpoints), among which there is Marvell's 9143 PCI-to_SATA controller based…
Alex
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OpenCL buffer map/unmap and enqueueWrite bandwidth

I have a performance problem for my opencl C++ wrapper, I need to transfer data from buffer d to buffer b as fast as possible (using map/unmap to achieve 6GB/s DMA speed of pci-e) then copy that data to buffer a (at device speed about…
huseyin tugrul buyukisik
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Use inheritance or code different USART variants

I have a USART class that transmits data using the tx interrupt. Now I want to create a variant that uses DMA to transmit data. What would you prefer: use inheritance to create two USART subclasses, e.g. ISRUSART, and DMAUSART? or just implement…
user2479653
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FAST DMA benefit from FPGA using threads in C++

I am transferring data from FPGA PCIe thru DMA, which is very fast. I have 500 data with each data comprise of 80000 BYTES. Hence the time for all 500 data receiving and saving in .bin file is 0.5 seconds. If I do the same in .txt file (which is my…
SJ_CAD
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Direct Memory Access with JTAG in Trust Zone

I'd like to know what prevents me from accessing memory in a DMA fashion, in the Trust Zone, when using JTAG? Thanks in advance.
AK87
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Need for Direct Memory Acess

What is the need of DMA?. What are the advantages of using DMA than normal transfer?. I searched it but not getting clarity. Any help, thanks in advance.
Siva Krishna Aleti
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Can I send via Infiniband data without using a DMA-controller?

Can I send data via Infiniband without using a DMA-controller and what the smallest size of packages can I send? That is, can I directly access to the memory of the remote CPU2-RAM from current CPU1-Core by using simple pointer (i.e. only x86-asm:…
Alex
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How to work with physical addresses as a network and how does DMA connect to it?

I am working on a network driver and am somewhat confused with the memory management. On the TX path, i receive a skb, as the lower layer expects to get only physical addresses, I think I need to call *virt_to_phys* and send the return value to the…
fashasha
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How can i translate dma_addr_t to virtual address in linux kernel?

I'm writing a PCI device driver and i need to allocate some memory for DMA, I'm using this function: void *dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle, int flag); I pass dma_handle to the device. The return value of…
yonigo
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dma_alloc_coherent fails when buffer > 2M on kernel 3.2

I have this x86 device and a kernel module that tries to allocate DMA memory. It has a parameter called dmasize that allows to control the size of allocated memory. I've noticed that allocation succeeds when dmasize=2M but not if larger. Even at…
shayst
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How to use the memory of the Xilinx-FPGA Virtex5/7 as a memory mapped into the x86-CPU's address space?

Is it possible to use the memory of the Xilinx-FPGA Virtex5/7 as a memory mapped into the virtual and/or physical address space of the Intel x86_64-CPU's memory and how to do it? As maximum, I need to use unified single address space with having of…
Alex
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