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Re: Interrupt handlers and mutex
On Dec 31, 2009, at 11:52 AM, Frank Zerangue wrote:
> Help request -- Mutex(9) indicates that mutex replaces the spl(9) system.
>
> (1) When writing an interrupt handler, should the handler acquire a spin
> mutex before modifying some IO that may be accessed also by a LWP?
Yes. and the mutex should be initialized to use IPL_VM.
> (2) What happens when the interrupt handler cannot acquire the mutex? Will
> the LWP that holds it ever be able to run again?
That can't happen. The cpu will spin until the mutex is acquired.
> (3) Will a LWP that holds a spin mutex be pre-empted by the scheduler?
no.
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