[GitHub] [mynewt-nimble] wes3 commented on issue #477: npl/riot: reduce default MSYS_1_BLOCK_SIZE to minimum

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wes3 commented on issue #477: npl/riot: reduce default MSYS_1_BLOCK_SIZE to minimum
URL: https://github.com/apache/mynewt-nimble/pull/477#issuecomment-506805052
 
 
   @haukepetersen  I can try to answer some of these but not all. First off, I do not think folks will have any issue changing the RIOT default values for the default block size. As to your calculation of 70 there are some things you do not need for the nrf51. It has been a very long time since I looked at the nrf51 but a couple of things I am pretty sure of: you do not need to account for the access address or CRC in your calculation. They are handled by HW if I remember correctly. There is also a structure used by the controller and that is called struct ble_mbuf_hdr. Not sure if you are using the nimble controller but if you are you will need to account for that.
   
   You could also restrict the default number of msys blocks; that will definitely help.
   
   Finally, if recollection serves, the 292 number comes from a maximum size PDU of 251 bytes using data length extension. I thought there was some documentation somewhere stating how that number was calculated. It certainly was not "random" :-) but without knowing exactly how it got calculated I could see how one would think that.
   
   Anyway, hope the above helps.

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