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Questions tagged [dma]

30 questions
11
votes
2 answers

When a disk read or disk write occurs, where does the data go?

I understand that there is such a thing as a disk controller which contains a buffer, but was wondering if the CPU reads directly from this buffer, or whether the data must first go to a specific location in memory, and then allow itself to be read…
Kaitlyn Mcmordie
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11
votes
8 answers

Un-allowed DMA capable bus/device(s) detected

My problem is how can I find out which device on my laptop is Un-allowed DMA capable. I tried disabling my USB devices and unplugging laptop from docking station. My colleague has same laptop model and he is not having same issue as I do. System…
Kresimir Kljucaric
  • 111
9
votes
2 answers

Are few UDMA_CRC_Error_Count errors in an SSD an issue?

Some SMART stats: Device Model: Samsung SSD 850 EVO 500GB Firmware Version: EMT01B6Q 9 Power_On_Hours 0x0032 099 099 000 Old_age Always - 252 12 Power_Cycle_Count 0x0032 099 099 000 Old_age …
Jodka Lemon
  • 264
4
votes
2 answers

Virtual Memory and MMU: when are they used and when not?

I'm wondering about how a Virtual Memory system could be managed alongside with a MMU when there's the need to mantain some "fixed" addresses in the address space. For example, when a machine boots up, the CPU starts reading the first instruction…
iMineLink
  • 143
3
votes
1 answer

Kernel bypass possible with non-specialised NIC?

Is it possible to perform kernel bypass and have a NIC send data to the user space (where I will write my network stack) with no copying, without having to purchase a specialised Solarflare etc NIC?
intrigued_66
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2
votes
1 answer

Debian loses harddisk on bootup 4 times and then boots. Why?

Dmesg Dump: http://paste.debian.net/44975 at time 32.832045 That error is delaying my boot process significantly. Does anyone know what this is about? Devices: Maxtor IDE drive with new cable on primary master on a ASUS TUSL2-C board with Intel 815…
Dampf Hammer
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1
vote
0 answers

IOMMU cache coherency

In today's x86/x64 motherboards there can be found IOMMU's from Intel and AMD. They allow peripheral devices to perform DMA (direct memory access) operations into system RAM using virtual instead of physical memory addresses. Now, let's assume that…
David
  • 11
1
vote
1 answer

IDE DMA sector numbering

I'm just playing around with the QEMU system emulator, and taking a look at the IDE disk emulation, specifically at the DMA disk accesses. I'm a little confused as to how DMA requests are actually addressed. For example, the first DMA request made…
Tony
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1
vote
0 answers

What leads to a "DMA timeout, restart DMA controller" error after updating a network driver?

I recently got a new MIOP network driver for my Mixtile Cluster Box, but after installing it and rebooting the system, I'm receiving such an error message in the syslog of the baseboard management controller: [ 504.173322] miop 0000:06:00.0: DMA…
Neppomuk
  • 369
1
vote
1 answer

How is I/O encryption handled in modern systems?

First: I've struggled with the question on which stackexchange to post this question since it involves OS knowledge, hardware knowledge but probably also other CS fields. Suggestions for a better stack site are welcome. I've just had a sudden…
RobIII
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1
vote
0 answers

What limits how much of the memory a PCIe device can address?

Some PCIe devices cannot read more than 4 GB of address space without an additional driver or modified driver. In such cases, what limits how much memory they can read? Is it the memory controller? Is it the firmware of the PCIe device? Or is it…
Joe Toe
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1
vote
0 answers

My Mouse lags on HDD Activity after Ubuntu 19.10 Upgrade

I have recently upgraded from Ubuntu 19.04 to Ubuntu 19.10. But after upgrade I noticed that my mouse starts lagging while doing file transfers or any hard drive activity. Can anyone explain why is this happening and how to fix it? Please help, I am…
Future King
  • 129
1
vote
0 answers

How to implementing a application with Linux DMA

As far as I know, Linux provides common DMA framework for various DMA engine and a device driver for DMA engine have to be implemented based on the the framework. Is the framework provide any system calls or mechanism for user application such as:…
user9270215
  • 11
0
votes
2 answers

How do I enable DMA on a SATA controller?

I don't see any section "IDE ATA/ATAPI controllers" in device manager: What does this mean? and Can I know on which devices DMA can be enabled?
cpx
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0
votes
0 answers

When doing IDE DMA on x86, can other CPUs access the memory?

I am unfamiliar with hardware. I am studying the IDE disk I/O and DMA on x86. I want to know that when doing a IDE disk I/O with DMA, can other CPUs access the memory (or exactly, the same memory region as the DMA)? Of course, we assume that the OS…
tamlok
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