Dear David, Thanks for your reply!
With regard to the second question, if we disallow programmers to use assembly code and assume ncc can perform global and inter-procedural alias analysis, can we safely conclude my aforementioned claim (programmers will not raise data races if they obey the race-free invariant)? Sorry for my stubbornness, because I want to perform fault analysis for nesC code. Best regards, Yours, Zhifeng Lai -----Original Message----- From: David Gay [mailto:[EMAIL PROTECTED] Sent: Thursday, July 05, 2007 11:44 PM To: Zhifeng Lai Cc: tinyos help; Philip Levis; Zhifeng Lai Subject: Re: [Tinyos-help] Some confusion on the classic nesC paper. On 7/4/07, Zhifeng Lai <[EMAIL PROTECTED]> wrote: > Dear Philip, > > (1) Yes, I see. Another question relates to this: you said that the call > graph of nesC code is fully known at compile-time. I conjecture that the > component diagrams can be treated as call graphs in programming literature, > and since the wiring relationships among components are totally determined, > the call graph is also determined at compile-time. Could you confirm my > understanding? Essentially, yes. > (2) I understand what you mean. However, I think in the application level, > there is no primitives that can alternate interrupt enable bits. So, does it > mean application developers will not raise data races if they obey the > race-free invariant? The atomic section is arbitrary C code, and C (well, gcc) allows you to insert arbitrary assembly code. So your statement "n the application level, there is no primitives that can alternate interrupt enable bits" is incorrect (e.g., on a mica2, asm("sei") would enable interrupts). Furthermore, to get back to the orignal question, the data-race detector is simplistic and does no alias analysis. So updates via pointers are not checked to see whether they can cause races. David Gay _______________________________________________ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
