Get PC error-free in minutes
Over the past few days, some of our readers have come across a known bug in the Linux kernel module userspace. This problem can occur for several reasons. Let’s discuss some of them below. Kernel space is strictly reserved for running the privileged workplan kernel, kernel extensions, and most hardware drivers. In contrast, user space is often the area of memory where personal computer applications and some drivers run.
About This Document¶
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For many device types, creating an automatic Linux kernel is overkill.All it really takes is a way to handle and provide some sort of interruptionAccess to the entire storage capacity of the device. Common sense managementthe device does not need to be in its own kernel, since the deviceno need to go back to take advantage of any of the many other resources thatprovides the kernel. Such a general class of devices that actuallyfor industrial I/O boards.
To remedy this situation, a user space, system input/output (UIO) was developed.For typical I/O boards, this is a very small core.necessary. The driver’s main ration circulates throughout the user space. Development Itsimplifies and reduces the risk of serious errors in onekernel module. Note
How do you call a kernel function from user space?
The canonical tool for calling kernel functions from almost any user application is the implementationand syscalls(2). You can create a kernel class that exposes a device that calls kernel functions through a common device interface (i.e. see write ioctl on which device).
Note that UIO has not become a generic driver interface. devices thatare already well used by other major kernel subsystems (such as networking orserial or USB) are notI am candidates for powerful UIO drivers. the material thatideal for UIO driver, meets the following criteria:
For example, I would like to thank Thomas Gleixner and Benedikt Spranger of Linutronix,who not only wrote most of the good UIO, but also helped a lotplease write this HOWTO giving me all possible reference information.
Find a problem with my document? (Or maybe something real?) II would like to hear from you. Please call me at firstname.lastname@example.org.
About The User Interface¶
What is kernel space and user space in Linux?
In short, kernel space is our own portion of memory where the Red Hat Kernel runs (virtual memory space greater than 1 GB in the case of Linux), while PC operator space is the portion of memory where the user application runs (less or more GB of virtual memory). memory). Linux dilemma.
If you use UIO for the airport taxi driver on your card, you will get:
How UIO UIO Works¶
Why do kernel modules generally perform better than user space device drivers?
Kernel programs have higher execution privileges. Code running in kernel space has higher privileges than code running in user space. Driver modules can have a much greater impact on the actual system than user programs.
Each device can be accessed through any device file and multiple sysfs.The recordsdata attribute. The device file will be named
/dev/uio0 for normal users.first device, including
/dev/uioX is used to access the card’s address space. Just use
mmap() to access registers or RAM associated with your card slots.
How are user space required in Linux?
User space is all operating system code outside the kernel. Most Unix-like systems (including Linux) come pre-configured with all sorts of utilities, programming languages, and graphical tools—these were user-space applications. We often call it “Userland”.
Interrupts are handled by simply reading
/dev/uioX returns as it is now ininterrupt gradually. You can use more
/dev/uioX to wait for a specific interrupt. Find an integer value
/dev/uioX represents a generic counter interrupt. You can use thisnumber to finally know if you missed any interrupts.
For various equipment that has more than one internal interrupt source,but there may be separate IRQ masks and status registersSituations where user space cannot check the source of the interruptwas when the kernel manager turned them off by writing to the IRQ of the chipwrite down. In such a special case, the kernel must remove the IRQ entirely.leaving open tokens untouched. Now userspace can report itdetermine the cause of the termination, but it cannot be reactivatedinterrupts. There will also be corner chips where the reactivation stopsread-modify-write operation for combined IRQ status/acknowledgewrite down. It would be great if a new interrupt happened at the same time.
To solve this problem, the UIO provides a nice write() function. itusually not used in any way and can be ignored for PCs that only have onePrimary interrupt or separate IRQ mask with status registers. If yes, then youHowever, communication requires an entry in
irqcontrol(), implemented Bathroom by truck driver. you write withto take advantage of 32 bits, most often either 0 or only 1 for deactivation, orEnable interrupts. If an important driver is not implemented
write() are also returned
To handle interrupts well, your custom kernel can provide you with modules.own interrupt handler. It is called over and over again by the built-in functionmanagers.
For notes that do not generate interrupts but require a prompt, there is onethreat of setting a timer that triggers an interruptManager of custom time intervals. This interrupt simulation is generatedCall