Messages in this thread | | | Date | Thu, 10 Oct 2002 15:55:18 -0700 | From | "H. Peter Anvin" <> | Subject | Re: weird semantics of cpu/*/msr |
| |
Martin Waitz wrote: > hi :) > > the i386 msr driver is a bit strange: > > * when reading/writing, it does not update the file position/msr register > * file position is used directly as msr register > > that is, reads with count>8 do read from the same register multiple > times, and writes overwrite themselves. > > i would expect the following semantics: > * file position is (msr register * 8). position%8!=0 is invalid > * read/write updating file position. > > that would make it possible to write/read multiple MSRs with one > syscall, which is very handy when initializing P4 performance counters. > > should i implement that behaviour? > of course it would break binary compatibility with existing > uses of that drivers. > perhaps we would need a new location for the new api. >
No, you should not.
Simply put, the semantics were chosen for what typically makes sense w.r.t. MSRs.
-hpa
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |