KDB entry on NMI

[Marcel Moolenaar]

On Jul 19, 2014, at 11:29 AM, Konstantin Belousov <kostikbel at gmail.com> wrote:
>> 
>> One may call kdb_enter on different CPUs at the same time and it's
>> also possible to call panic on multiple CPUs at the same time (but
>> we serialize panic() right now). What if we let kdb_enter at al deal
>> with concurrency, instead of doing it specifically for NMIs?
> Then, on 80-threads machine I get the 80 ddb sessions on NMI broadcast,
> like now.  With your proposal, it will be somewhat better, since
> sessions are serialized, so I can do the reboot from the first one.

There's value to send the NMI to all CPUs: you'll be pretty sure
that if there's a CPU that can handle it, it will get the NMI.
Sending it to a single CPU has the downside that if that CPU is
unable to handle the NMI (corrupted page tables, locked on some
chipset access, held in reset, powering down, whatever one can
think of) you're out of luck.

Are we acking the NMI on all CPUs right now?

-- 
Marcel Moolenaar
marcel at xcllnt.net


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