Kumar Gala wrote: > > On Oct 2, 2009, at 9:46 AM, Timur Tabi wrote: > >> Michael Barkowski wrote: >>> Just wondering - is there a case where using volatile for UCC >>> parameter RAM for example will not work, or is the use of I/O >>> accessors everywhere an attempt to be portable to other architectures? >> >> 'volatile' just doesn't really do what you think it should do. The >> PowerPC architecture is too complicated w.r.t. ordering of reads and >> writes. In other words, you can't trust it. >> >> No one should be using 'volatile' to access I/O registers. > > See Documentation/volatile-considered-harmful.txt >
I'm happy to adopt your interpretation of it, and I appreciate the explanation. from Documentation/volatile-considered-harmful.txt: > - The above-mentioned accessor functions might use volatile on > architectures where direct I/O memory access does work. Essentially, > each accessor call becomes a little critical section on its own and > ensures that the access happens as expected by the programmer. Part of it was that I wondered if this was one of those architectures. I guess not. -- Michael Barkowski 905-482-4577 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
