On Tue, Mar 17, 2015 at 10:57:06AM -0400, Frank Pagliughi wrote: > I'm in agreement, for what it's worth. I've had to make use of the > binary semaphore through the C++ API, and it always made me wonder why > it wasn't brought out to the public/C API.
I've been asking that for 15 years. OK, I exaggerate. I just looked itup and the first thread I started on this top was March 2001, so it's only been 14 years. The reason given for lack of a binary semaphore C API was: It was never intended that the KAPI be a complete reflection of the kernel implementation. It is meant to be a consistent, self-contained, small API that can be used by C applications. Like the uITRON and POSIX APIs it only exposes a subset. It was considered unnecessary to export binary semaphores, since a counting semaphore initialized to 1 is functionally equivalent. If I had had my way the KAPI would have been even more minimal that it currently is. -- Nick Garnett, eCos Kernel Architect Red Hat, Cambridge, UK Except a counting semaphore initialized to 1 is _not_ functionally equivalent to a binary semaphore in all cases. I pointed this out and provided examples of sequences of wait/post where the behavior differs, but was told those sequences were "bugs" and (jokingly, I hope) if I didn't shut up and stop asking questions then the C++ binary semaphores would be removed copletely. It was quite clear that Nick was adamantly opposed to providing a C API for binary semaphores and that the needs of eCos users' application code were to be overruled by his idea of what an comprised a minimal, complete, elegent set of C APIs: people who want to write/port C apps that use binary semaphores should just and rewrite the application code. IOW, all you really need are two-input NAND gates to model any Turing complete machine so stop bitching and get to work. -- Grant -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
