Re: [Xen-devel] [PATCH v2 3/5] dbg_rw_guest_mem: Conditionally enable debug log output

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2014-01-08 at 09:28 -0500, Don Slutz wrote:
> > Using volatile is almost always wrong. Why do you think it is needed
> > here?
> 
> This was from Mukesh Rathor:
> 
> http://lists.xen.org/archives/html/xen-devel/2014-01/msg00426.html
> 
> I saw no reason to make it volatile, but maybe "kdb" needs this? Happy
> to change any way you want.

I'm not the maintainer but if I were I'd say drop the volatile and maybe
mark it __read_mostly and perhaps __used too (since it's static it might
otherwise get eliminated).

> > If anything this variable is exactly the opposite, i..e __read_mostly or
> > even const (given that I can't see anything which writes it I suppose
> > this is a compile time setting?)
> 
> That has been how I have been testing it so far (changing the source
> to set values).  Mukesh claims to be able to change it at will.  Not
> sure how const may effect this.

I presume this is using kdb and marking it const would probably cause
the dead code to be eliminated so it is worth not doing that for his
sake.

Ian.


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