On Mon 09 Mar 2009 at 12:21PM, Jonathan Adams wrote:
> The main effect of the currently proposed kmem walker is to unify the
> 6 kmem walkers: "kmem", "bufctl", "free", "freectl", "free_constructed",
> "freectl_constructed" into a single "kmem" walker, and adding the ability
> to walk all of the different varieties from the per-cache walkers. So
> you can do:
>
> ::walk kmem_alloc_8192 - -f
>
> to walk the free buffers in kmem_alloc_8192. (the '-' is for the
> not-well-known "variable" argument to ::walk)
While this makes plenty of sense, I think this particular bit
of syntax is going to trip up a lot of people who are not experts
at this sort of thing. I have a couple of questions about it, as
a result:
1) Should we change the syntax? I can think of at least
two approaches. I'm not in love with either....
::walk [-something <varname>] <walker> [walker options]
Or splitting ::walk into '::walk [options]' and
'::walkvar <var> [options]'
2) I saw that your code supports:
::walk kmem_alloc_8192 - -f
and
::walk kmem_alloc_8192 -- -f
It seems like the latter form is better? It makes more
sense to me from a getopt compatibility perspective.
3) If not (1), then could we detect likely mistakes and tell
the user what to do?
Today:
> ::walk kmem_alloc_8192 -f
mdb: '-' may not be used in a variable name
Now, looking at your code, I expect it will print the same thing--
but
as a result, the message is effectively telling the user that
passing a
'-' is going to be illegal. Could we do something like this?
> ::walk kmem_alloc_8192 -f
mdb: '-' may not be used in a variable name.
mdb: did you mean: ::walk kmem_alloc_8192 -- -f?
Thanks,
-dp
--
Daniel Price, Solaris Kernel Engineering http://blogs.sun.com/dp
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