# Priority initialization

**URL:** <https://forums.freertos.org/t/priority-initialization/564>\
**Category:** Kernel\
**Created:** [April 24, 2012, 10:11pm UTC](https://forums.freertos.org/t/priority-initialization/564 "2012-04-24T22:11:39Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![system](https://d2v6vdsk2p900z.cloudfront.net/original/1X/7fc8fdb729c645aab5b20282bbe34e57cb407be6.jpeg) [@system](https://forums.freertos.org/u/system)\
**Post date:** [April 24, 2012, 10:11pm UTC](https://forums.freertos.org/t/priority-initialization/564/1 "2012-04-24T22:11:39Z")

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**anonymous** wrote on [Tuesday, April 24, 2012](https://sourceforge.net/p/freertos/discussion/382005/thread/1a42e593/#0e7b):

Im using the Cortex M3 port of freeRTOS (specifically the lpc1763) and using Rowley Crossworks.

Ive been diving into the interrupt priorities of my application lately to be sure I understand everything is running as i intend.&nbsp; Following the code around for a while and I ran into the following lines:

portBASE\_TYPE xPortStartScheduler( void )  
{  
/\* Make PendSV, CallSV and SysTick the same priroity as the kernel. \*/  
\*(portNVIC\_SYSPRI2) |= portNVIC\_PENDSV\_PRI;  
\*(portNVIC\_SYSPRI2) |= portNVIC\_SYSTICK\_PRI;  
}

Two questions:  
1) The register is defined as portNVIC\_SYSPRI2, but the register its pointing to is the 3rd system priority handler, so the name is perhaps a bit misleading.&nbsp; Not really my main question though….just an observation.

2) In the comment it says the CallSV priority is set, but I dont see where that instruction happens, in fact… in my program memory it is currently 0.&nbsp; Could this negatively affect my application?&nbsp; I saw a note on another post that CallSV is only used to start the scheduler, so maybe this is ok?

Thanks.

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**Author:** ![rtel](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rtel/32/31_2.png) [@rtel](https://forums.freertos.org/u/rtel)\
**Post date:** [April 25, 2012, 5:14pm UTC](https://forums.freertos.org/t/priority-initialization/564/2 "2012-04-25T17:14:35Z")

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**[rtel](https://sourceforge.net/u/rtel/)** wrote on [Wednesday, April 25, 2012](https://sourceforge.net/p/freertos/discussion/382005/thread/1a42e593/#9962):

SVCall is only called to kick the scheduler off, so never called when the scheduler is actually running, so its priority is not set.

Regards.