Re: sharing data (can ISR be pre-empted???)

[Tyler <tyler@xxxxxxxx>]

Tyler wrote:
> mandeep sandhu wrote:
>
> > hi all,
> > i've heard that the linux kernel is preemptive from 2.5 onwards....
> > so can an ISR be preempted by the kernel. as i understand an ISR doest 
> > not
> > have a process context, so then what can preempt it????
>
>
> Yes you're right. An ISR has no process context. But an ISR can be 
> interrupted by some code lika for example another ISR. Interrupts can be 
> nested in Linux (even in 2.4).
> And in 2.5 and 2.6, ISR can be preempted by a thread or anything else 
> which has a higher priority.
Well what I said is wrong. BH,ISR and tasklets are execute in a non 
preemptive way : they cannot preempted by a process which has a higher 
priority.
Sorry for the mistake :)


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