[ECOS] question about Synchronization Levels in eCOS? Thanks a lot.

QiangHuang jameshq@liverpool.ac.uk
Tue May 6 12:52:00 GMT 2003

Hi all:
   I have some question about the Synchronization Levels in ecos.  Can I set
the flag bit or post semaphore in a ISR()? if not why? As mentioned in the
ecos doc as:
" Since it would be dangerous for an ISR or DSR to make a call that might
reschedule the current thread (by trying to lock a mutex for example) all
functions in this API have an associated synchronization level. "

I can't completely understand why calling a function :
yg_drv_cond_signal( )  in isr() or dsr() should be forbidden. Is this just
to signal a condiction probably awaken a waiting thread. Then the awaken
thread might be able to run after exiting isr( ) and dsr( ), if this is
thread that the application want to run when such IRQ occured. so why ? how
does this compare to "cyg_flag_setbits( )" and "cyg_semaphore_post( )"

Thanks a lot.

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