directives allowed from an ISR

[Eric Norum]

On Thursday, November 28, 2002, at 08:43  AM, Stan wrote:

>
>
>> On Thu, 28 Nov 2002, Stan wrote:
>>
>>> Hi,
>>>
>>>
>>> Can I call semaphore_obtain from an ISR ?
>>
>> You are NOT allowed, only rtems_semaphore_release.
>
> Why ?
>
> Stan.
>

Actually, I think you *can* call rtems_semaphore_obtain from an ISR if 
you specify RTEMS_NO_WAIT.
ISRs must not issue a directive which blocks, since there's no task 
context to save/restore.

-- 
Eric Norum <eric.norum at usask.ca>
Department of Electrical Engineering
University of Saskatchewan
Saskatoon, Canada.
Phone: (306) 966-5394   FAX:   (306) 966-5407