nanosleep crashed my kernel

Chuck Swiger cswiger at
Thu May 29 22:04:25 PDT 2003

Anurag Chaudhary wrote:
> I used nanosleep() in my device driver, but it crashed the kernel saying 
> pagefault in kernel mode.
> Can anybody please suggest some other method to be used in a kld to sleep

When you put the kernel to sleep, what were you expecting to wake it up?  :-)

A literal answer would be an interrupt, but in many contexts, such as device 
drivers, tend to block receipt of new interrupts while servicing the existing 
one.  Regardless, there is a critical design methodology involved: you shouldn't 
ever block or busy-wait in the kernel, at least if you can possibly avoid it. 
Look into continuations and performing a context swap to a runnable process 
until the next interrupt happens and your device driver can make more progress.


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