Re: [RFC] [PATCH] sysfs support for Xen attributes

[Greg KH]

On Thu, Jan 12, 2006 at 01:54:46PM +0100, Gerd Hoffmann wrote:
>   Hi,
> 
> >>Huh?  You can't just throw a "MODULE_VERSION()", and a module_init()
> >>somewhere into the xen code to get this to happen?  Then all of your
> >>configurable paramaters show up automagically.
> >
> >No, I can't. Xen does not have modules. Xen loads and runs linux.
> 
> You can.  Just look at a recent drivers/xen/blkback/blkback.c, the 
> module parameters specified there show up in 
> /sys/module/blkback/parameters, no matter whenever the code was built 
> statically into the kernel or as module (which curently doesn't work for 
> blkback anyway ...).
> 
> Any read-only attributes can trivially be implemented that way.  Simple 
> writable stuff (balloon driver?) probably too, I don't know whenever a 
> notify callback on parameter changes is possible though.

Yes it is.

> The current /proc files which are not simple attributes such as 
> /proc/xen/{privcmd,xenbus} are a bit more tricky, not sure what the best 
> approach for these is.  privcmd returns a filehandle which is then used 
> for ioctls (misc char dev maybe?).  xenbus can be opened and (I think) 
> read(2) on to listen for any xenbus activity, much like /proc/kmsg. 
> Suggestions what to use here instead of procfs?  Or just leave it there?

Your own filesystem?  You can do that in about 200 lines of code these
days :)

And no, it does not belong in procfs.

thanks,

greg k-h
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