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Date: Thu, 4 Dec 2008 11:50:56 -0700
From: Tom Rini <trini@kernel.crashing.org>
To: openembedded-devel@openembedded.org
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Subject: Re: invalidating udev cache, how?
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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 :)

Updating the cache at shutdown means you can end up with random
hotplugged junk sticking around.  It's probably not much messier than
just starting out with a few maybe nodes in your cache, but it's worth
noting.

-- 
Tom Rini