▁messages ▁to ▁the ▁other ▁by ▁writing ▁the ▁message ▁into ▁the ▁pre - det erm ined ▁address ▁and ▁then ▁sending ▁an ▁interrupt ▁to ▁signal ▁the ▁other ▁processor ▁that ▁a ▁new ▁message ▁is ▁available . ▁When ▁transfer ring ▁data ▁buff ers , ▁only ▁a ▁pointer ▁to ▁a ▁given ▁buffer ▁needs ▁to ▁be ▁passed ▁since ▁the ▁buffer ▁res ides ▁in ▁shared ▁memory ▁that ▁is ▁accessible ▁to ▁both ▁the ▁process ors . ▁ ▁AR M ▁buffer ▁addresses ▁must ▁be ▁translated ▁into ▁physical ▁addresses ▁when ▁being ▁presented ▁to ▁the ▁D SP , ▁as ▁the ▁D SP ▁does ▁not ▁have ▁an ▁MM U ▁or ▁a ▁concept ▁of ▁virtual ▁address ing . ▁ ▁Once ▁the ▁processor ▁receiving ▁the ▁message ▁has ▁read ▁it , ▁it ▁marks ▁a ▁flag ▁in ▁shared ▁memory ▁to ▁indicate ▁that ▁the ▁message ▁memory ▁is ▁now ▁available ▁to ▁be ▁re written ▁with ▁another ▁message . ▁▁ ▁The ▁D SP ▁included ▁in ▁many ▁Da V inci - based ▁devices ▁generally ▁runs ▁T I ' s ▁D SP / BI OS ▁R T OS . ▁When ▁multiple , ▁heter ogeneous ▁cores ▁are ▁included ▁in ▁the ▁device ▁( e . g . ▁DM 6 4 4 x ), ▁D SP / BI OS ▁Link ▁drivers ▁run ▁on ▁both ▁the ▁AR M ▁processor ▁and ▁the ▁D SP ▁to ▁provide ▁communication ▁between ▁the ▁two . ▁ ▁Oper ating ▁systems ▁ ▁A ▁number ▁of ▁AR M 9 ▁operating ▁systems ▁support ▁D SP / BI OS ▁Link ▁drivers : ▁Mont av ista ▁Linux ▁Time S ys ▁Linux ▁M ent or ▁Graphics ▁N uc le us