On Sun, Jan 04, 2009 at 10:20:55PM -0800, Russ Cox wrote: > There are some devices in Plan 9 that simply don't "virtualize", > because at a deep level they are tied to process state that > doesn't go through the file system. Dup manipulates the file > descriptor table, not files themselves. Pipe accesses files that > have no name in the file system. The pid returned by getpid > needs to match the pid returned by the parent's fork; it really > needs to be the process's actual pid. For example, suppose > a process wants to know . If getpid read from /dev/pid > instead of #c/pid, then running "iostats rc -c 'echo $pid'" > would show iostats's pid, not rc's. What then if rc wants to send > itself (or, more likely, its note group) a note, or fiddle with > one of its /proc files? It would be manipulating iostats, not > itself. > >[snip #s #a and #D]
This just means that these services need to be mounted at the canonical place in the namepsace atop the root provided by iostats. That yields equivalent behavior -- the kernel sees the right process making the call and iostats sees nothing at all -- but it is, I agree, unsatisfactory. --nwf;
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