Menu
I'm writing a user space program and a kernel space device driver.
Goal: Once an interrupt occurs, user space program needs to do something quickly.
My naive method: User space program uses ioctl to call wait_event_interruptible(), kernel ISR calls wake_up_interruptible() to wake up user space program. It turns out that it takes too much time from interrupt to user space.
Is there any better way?
Thanks!
548
Interrupt handling in Linux. In Linux the interrupt handling is done in three phases: critical, immediate and deferred. In the first phase the kernel will run the generic interrupt handler that determines the interrupt number, the interrupt handler for this particular interrupt and the interrupt controller.
And it uses proc, ioctl, and system call to realize the communication between Kernel and User Spaces. But these methods must keep user space synchronizing with kernel space. So, Netlink mechanism is used, and ONU logs are recommended, which is difficult for proc, ioctl, and system call.
Kernel-mode code is always interruptible: an interrupt with a higher IRQL value can occur at any time, thereby causing another piece of kernel-mode code that has a higher system-assigned IRQL to be run immediately on that processor.
An interrupt is simply a signal that the hardware can send when it wants the processor's attention. Linux handles interrupts in much the same way that it handles signals in user space. For the most part, a driver need only register a handler for its device's interrupts, and handle them properly when they arrive.
There is a similar question asked here:
Notify gpio interrupt to user space from a kernel module
Please check above question. However, i can provide my approach which i suggested there as well.
You can send a signal to user space thread from kernel API, which can help u run non-blocking:
send_sig(int sig, struct task_struct *p, int priv);
You need to be aware of pid of user thread in Kernel. You can over come this by writing pid of user process via /proc and then kernel reading the pid. With this arrangement, when there is an interrupt, kernel can send signal to user thread. In case your process restarts or gets killed, you will have to update the pid via proc. Just for status notification you can use this method; however if you like to transfer data along with status than Netlink or char driver mechanism is good way.
130
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
