SYSTEM eCos – Embedded Configurable Operating System - MARS
SYSTEM eCos – Embedded Configurable Operating System - MARS
SYSTEM eCos – Embedded Configurable Operating System - MARS
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<strong>SYSTEM</strong>Y CZASU RZECZYWISTEGO<br />
<strong>SYSTEM</strong> <strong>eCos</strong> <strong>–</strong> <strong>Embedded</strong> <strong>Configurable</strong> <strong>Operating</strong> <strong>System</strong><br />
Piotr MALECKI<br />
INTERRUPT HANDLING (cont.):<br />
Somehow similar problem <strong>–</strong> to the question of interrupts being enabled or disabled -<br />
is the problem of the kernel scheduler lock.<br />
Scheduler may be locked in response to function like:<br />
cyg_mutex_lock<br />
cyg_semaphore_post<br />
which may be issued by the kernel for time of manipulation with some data structures<br />
after which the lock is released.<br />
Locking the scheduler may cause pending some DSRs and some chain of synchronization events<br />
influencing waking up of threads of various priorities.<br />
... various possible scenarios ...<br />
in which one can illustrate that the two-level approach to interrupt handling realised by <strong>eCos</strong><br />
allows fo safe solutions ( .. e.g. it is safer to leave cyg_semaphore_post to a DSR rather than<br />
to ISR which disabling interrupts may cause corruption of kernel data structure or even loss<br />
of some thread that would never run again).<br />
9/14
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