SIMIA32: make port_lock/port_unlock nesting-aware#66
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The SIMIA32 simulator port used a simple boolean flag (0/1) for port_lock()/port_unlock(). When ChibiOS timer callbacks call code that uses S-class chSysLock/chSysUnlock (e.g. CriticalSectionLocker inside efiPrintfInternal), chSysUnlock() would reset the flag to 0 even though chSysLockFromISR() had set it to 1 — effectively dropping the ISR lock and corrupting the cooperative scheduler's ready list and delta list. On real ARM hardware this never happens because both S-class and I-class locks manipulate BASEPRI identically, so nesting is implicit. Switch to a counter (++/--) so nested lock/unlock pairs balance correctly, matching the ARM port's behavior.
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The SIMIA32 simulator port used a simple boolean flag (0/1) for port_lock()/port_unlock(). When ChibiOS timer callbacks call code that uses S-class chSysLock/chSysUnlock (e.g. CriticalSectionLocker inside efiPrintfInternal), chSysUnlock() would reset the flag to 0 even though chSysLockFromISR() had set it to 1 — effectively dropping the ISR lock and corrupting the cooperative scheduler's ready list and delta list.
On real ARM hardware this never happens because both S-class and I-class locks manipulate BASEPRI identically, so nesting is implicit.
Switch to a counter (++/--) so nested lock/unlock pairs balance correctly, matching the ARM port's behavior.