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

[Gerd Hoffmann <kraxel@suse.de>]

   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.

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?

cheers,

   Gerd

-- 
Gerd 'just married' Hoffmann <kraxel@suse.de>
I'm the hacker formerly known as Gerd Knorr.