I am trying to write sample usb driver for sel4 in userspace. can anybody have an idea about sel4 user-space driver please share with me...
If anyone have example code for sel4 user-space driver(sample drivers) please share with me...
seL4 is a microkernel. its architecture is base on transfer most of kernel modules (for example filesystem driver, network stack driver , ... ) to user space area.
so in its repository all driver like libusbdrivers, libethdrivers ,libsdhcdriver ,... work in user space mode. so you can check them.
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I'm a software developer but I'm a newbie to embedded software development.
I have a Zynq Ultrascale board that has an Axi DMA in its Hardware and I want to access this DMA from Linux.
I know I should use DMA-Engine to Access DMA in Linux and I found the following link which is the Xilinx DMA driver, but I can't add these files to my qt project without any errors and I received file(header file) not found errors.
drivers/dma/xilinx/xilinx_dma.c
I have a piece of scattered information about the DMA driver, Device tree, and DMA-Engine but I know nothing about how to utilize these to access hardware DMA.
I built a Petalinux project and add DMA-Engine and DMA Test client to its kernel.
I don't know adding DMAEngine to the Petalinux project is enough or I should have a driver as well.
I don't know adding hardware specification (by .xsa file and .bit file) to the Petalinux project is enough or I should add a device tree to my Linux for detecting DMA as well
I lookup a step-by-step tutorial on how to set up Linux and qt creator for accessing DMA,
or at least a clear roadmap to my target.
thank you in advance.
First of all, you are facing errors when adding xilinx_dma.c to the Qt project because this file is meant to be compiled as part of kernel or as a kernel module.
Adding DMA Engine to Petalinux is not enough to work with DMA from user space. DMA Engine only provides a standardized API to let different DMAs be integrated into kernel. You need to add a client driver as well. Xilinx, as far as I know, has provided a simple client driver called DMA Proxy Driver. It also includes some simple examples that show how you can access DMA from the user space. However, if your application needs high bandwidth, you probably need to consider other options.
There is also an open source client driver for Axi DMA which achieves higher bandwidths compared to Proxy DMA Driver. It's user space API also allows you to register a callback function to be called whenever a transaction is finished.
The third option is to implement the driver in the user space. This can be done by defining the DMA as a UIO device in the device tree and access its register map directly from the user space. In this case, you need to allocate some contiguous memory blocks in the kernel space to avoid complications with MMU, which cannot be dealt with from the user space.
Please anyone explain the exact differences?
While implemntin the driver code, I have facing an issue in both places.
We will need more information for getting to the root of your issue. What exact problem you are facing. Well as per your query different types of driver details are given below.
Physical Device Driver: A physical device driver is a driver for a specific piece of hardware. This drivers are written by device vendor. Some of the examples are ethernet drivers, graphics drivers(intel, nvidia) etc
Logical Device Driver: A logical device driver is a high level abstraction of how a device behaves. The logical device driver talks to the physical device driver for you to keep you abstracted from the underlying hardware. So Logical device drivers are written by operating system vendor. some of the examples are generic drivers provided by microsoft like USB etc
Virtual Device Driver: Virtual device drivers are drivers which emulates a hardware device. It emulates a piece of harware, so that softwares can have illusion of accessing real hardware. Some of the virtual device driver examples are virtual network adapter, virtual DVD/CD drive, virtual disk device etc
I need to create a driver, which will behave similar to software RAID. E.g. driver will need to communicate to multiple physical disks (or maybe even network resources), and shall look like a disk to the OS.
So two main questions are:
1) Are EFI drivers recognized and supported by Windows, MacOS X and Linux? E.g. can these systems use EFI disk drivers, and ?
2) Is it possible in theory to write such a driver for EFI? My primary concern is possibility of accessing other EFI disk drivers from your own virtual disk driver.
I only have time for a quick-ish reply, forgive me for brevity!
Are EFI drivers recognized and supported by Windows, MacOS X and Linux? E.g. can these systems use EFI disk drivers, and ?
To my knowledge, only the bootloaders for these OSs use the UEFI driver stack for loading the native OS kernel and drivers. Once ExitBootServices() is called by the bootloader, most of the drivers are unloaded, and (according to the spec) no calls to handle-based drivers may happen after this, meaning no disk drivers. Like a traditional bootloader, a UEFI bootloader is only using the basic drivers long enough to load the OS's native drivers. You can also use these drivers in the preboot environment if you'd like (although it sounds like you don't!).
TL;DR No, these systems can't use UEFI drivers other than for loading the OS.
Is it possible in theory to write such a driver for EFI?
You should definitely be able to layer your UEFI driver on top of the existing stack. It might be a little tricky if you haven't worked with UEFI before, but conceptually the system is very modular. There appear to be a number of resources on the Internet to help you out, and there is always Beyond BIOS: Developing with the Unified Extensible Firmware Interface by Vincent Zimmer.
As far as testing goes, you can use one of the simulators provided in Intel's EDKII (if you're on Windows, you should probably use the Nt32 project, it works well with Visual Studio).
TL;DR Yes, you can write this driver, but it will only work for bootloaders and applications in the pre-boot environment.
1) Are EFI drivers recognized and supported by Windows, MacOS X and Linux? E.g. can these systems use EFI disk drivers, and ?
No. Once you run ExitBootServices() it goes bubye. You can have a RunTimeDXE Driver, but those are incredibly limited. They cannot allocate memory (the VM Map is controlled by the OS) and they don't have access to any EFI APIs any more. They can be used to transfer information from the Firmware to the OS, but a better choice would be a private EFI Table.
2) Is it possible in theory to write such a driver for EFI? My primary concern is possibility of accessing other EFI disk drivers from your own virtual disk driver.
The bootloader is the only one able to use the EFI drivers. If you want to go to the OS level, you need to write your own OS driver that gets the information from the EFI driver using EFI System Tables. Such examples are Full Disk Encryption implementations.
In theory you would need to write an EFI Block Driver based, a Windows IO Filter or BUS/Volume Driver, an OS X IOStorageFamily KEXT and a Linux Block Device Driver all of them transferring the information from firmware to OS using EFI Tables, Variables or RuntimeDXE.
RuntimeDXE implementations are incredibly difficult due to the conversion to Virtual Memory Maps from the flat addressing available in the EFI.
I want to write a program which will "lock" a computer to a user determined wireless network.
It should automatically establish and maintain the connection with the specified network
Other networks should be hidden and/or inaccessible while the program is running
Should be compatible with Windows XP - 8
Should work for all wireless cards
Could I create an NDIS filter driver or NDIS intermediate driver for this? Which one is a better option? Also, the MSDN documentation I linked does not seem to provide good information about how to actually write the driver, where can I find that?
I am aware that there are programs out there like lojack for laptops that get installed on the BIOS, but I'm still a little confused. When reading about lojack, it seems to me that they can't fully located the laptop's location until the user logs in and tries to access the internet. So I'm thinking that it's a BIOS application so that it wouldn't matter if the thief reformats the HD.
So my question is, does anyone have any ideas of how an internet enables BIOS application would be written. I'm not looking for full answers -- just ideas or resources to get started. For example, is such a thing written in assembly? Once one such app is written, how does it get transfered to the BIOS.
Does the BIOS program itself recognize that there is an internet connection (when the thief logs on to the OS). Or upon logon, does additional processes get spawned? Are there any resources/websites that anyone can direct me too?
You didn't mention whether you were interested in legacy BIOS or EFI BIOS, but I would mention that with EFI there is the capability of writing EFI applications. See Intel Press:
Harnessing the UEFI Shell
The EFI Application toolkit comes with a complete TCP/IP network stack:
http://www.intel.com/technology/efi/toolkit_overview.htm
More at tianocore.org
Regarding "LoJack"-style solutions, one of the providers of this technology is Absolute Software's Computrace product.
Basically there are 3 components: 1) a software component that runs in the OS; 2) a BIOS component which is baked into the system BIOS (accomplished via Absolute working with the PC vendor); 3) servers at Absolute software that talk to the PC.
For more information on how it works visit:
http://www.absolute.com/en/company/Computrace-Persistence.aspx
(see especially the demo video on this site)
To learn something about BIOS, one good source is coreboot.org. It is an open source BIOS (or firmware) and support some physical machines.
Legacy BIOS is written in assembly language, but new generations, such as UEFI or coreboot, are written mostly in C language. BIOS program is stored in the ROM, and executed by the CPU automatically.
The BIOS program itself does not access the internet or perform any of the advertised functions. The LoJack addition to the BIOS firmware is a file copying/patching utility - at boot up it can check the harddrive for a copy of Windows and proceed to silently install/repair the LoJack service if it has been removed. The service itself includes several measures to lower it's profile and prevent itself from being disabled (similar to how many trojans and malware run several processes that each restore the other if one is disabled or killed).
The LoJack BIOS program can't do anything if a unsupported operating system (like Linux) is installed after the harddrive is wiped.