[RFC] Invalidating udev cache...

[Denys Dmytriyenko <denis@denix.org>]

On Tue, Mar 03, 2009 at 08:16:48AM -0700, Tom Rini wrote:
> On Tue, Mar 03, 2009 at 08:24:44AM +0100, Koen Kooi wrote:
> > On 03-03-09 06:11, Denys Dmytriyenko wrote:
> >> On Thu, Dec 04, 2008 at 06:41:50PM +0100, Koen Kooi wrote:
> >>> On 04-12-08 18:09, Mike (mwester) wrote:
> >>>> Mike (mwester) wrote:
> >>>>
> >>>>> A slight improvement would be to make the dev.tar file dependent upon
> >>>>> the bootargs; i.e. invalidate /etc/dev.tar file if the boot command line
> >>>>> doesn't match the current command line.  This could be a very fast
> >>>>> operation, just "cmp /proc/cmdline /etc/dev_cmdline" or similar.
> >>>> As I consider this further, we could actually just save and compare
> >>>> /proc/atags if that's present on the device in question (falling back to
> >>>> /proc/cmdline if not present).  That would catch *any* changes passed in
> >>>> to the kernel via the bootloader.
> >>>>
> >>>> Flashing a new kernel would seem to be another logical place to
> >>>> invalidate the cache, so adding a comparison of "uname -rv" would be a
> >>>> reasonable way to catch that.
> >>> That should indeed take care of bootargs and kernel version changes. I'm
> >>> still tempted to add option 2) to all that :)
> >>
> >> Sorry for bringing up this old discussion. Are there any plans to implement
> >> the above checks in udev?
> >
> > Plans yes, time no :(
> 
> Can we make sure they're optional?

I'd like to revive this old topic and propose a patch, which implements most 
of the above points. I'm not sure about making it optional and /proc/atags. 
So, anyway, the patch will follow, please provide comments.

-- 
Denys