Change Clock Frequency

Gedare Bloom gedare at
Mon Jul 29 21:38:19 UTC 2019

On Wed, Jul 24, 2019 at 8:59 AM Michel Macena <mmacena.eng at> wrote:
> Hi, I'm working with an ERC 32 target board and would like
> to change the system clock frequency. There is a file in $PROJECT_HOME/src/rtems/bsps/sparc/shared/start called Start.s. In this file there is a line for
> clock speed:
>>   .word 0x0a, 0, 0, 0 ! 7E (10 MHz default)
> I want to change to 8MHz so  I know that I have to change
> to 0x08. However after the change can I just recompile
> my programs or do I need to rebuild the RTEMS toolchain ?
You will have to recompile the BSP, but not the entire toolchain.

Note: you can also program the CLOCK_SPEED variable, for example see

> Also if I need to rebuild could someone explain how can I rebuild without needing to do the whole install process ? rebuild just the bsps ?
Typically you can just go to your build directory and run 'make'
again. If you did not modify any of the build files (configure/make
stuff), this usually just works. Sometimes though it might not
recompile the testsuites (watch for the linking) in which case you
might go to the testsuites subdirectory and run make clean && make
again if you need them re-linked.

Or, you could delete your build tree and rerun configure && make && make install

Then you should have updated the BSP, I guess.

> Thanks !
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