Messages in this thread | | | Subject | Re: [Fastboot] [RFC][PATCH] Add missing notifier before crashing | From | (Eric W. Biederman) | Date | Fri, 02 Jun 2006 10:39:42 -0600 |
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Vivek Goyal <vgoyal@in.ibm.com> writes:
> So basically the idea is that whatever one wants to do it should be done > in the next kernel, even notifications. But this might require some data > from the context of previous kernel, for example destination IP address etc. > So the associated data either needs to be passed to new kernel or it shall > have to be retrieved from permanent storage or something like that.
Yes.
Except when under tight time constraints this is clearly possible. When under time constraints things are more dicy. I expect that with a tuned kernel you can be back in user space in about 1 second.
Detecting a failure is hard and slow. Unless the condition that triggers the panic is the initial source of the panic it is quite likely a time window less than 1 second has already elapsed.
So I am certainly willing to discuss this but until I see a clear model where a new kernel will not meet the time constraints for some fairly fundamental reasons, and that a crash notifier will almost always meet those same time constraints, I can't imagine a persuasive case.
The panic notifier itself is barely used and it seems to exist only because we didn't have a general purpose policy mechanism.
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