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Re: Boot time and 3 sec in warning_print

  • To: Jan Beulich <jbeulich@xxxxxxxx>, Julien Grall <julien@xxxxxxx>
  • From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
  • Date: Mon, 15 Feb 2021 15:00:42 +0000
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  • Cc: <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Jürgen Groß <jgross@xxxxxxxx>, Anders Törnqvist <anders.tornqvist@xxxxxxxxx>
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On 15/02/2021 10:41, Jan Beulich wrote:
> On 15.02.2021 11:35, Julien Grall wrote:
>> On 15/02/2021 08:38, Jan Beulich wrote:
>>> On 15.02.2021 09:13, Jürgen Groß wrote:
>> What was just an "annoyance" for boot can now completely wreck your 
>> guests and system (not many software can tolerate large downtime).
>> So I think we either want to drop the 3s pause completely or allow the 
>> user to decide whether he/she cares about it via a command line option.
>> I am leaning towards the former at the moment.
> I'm afraid I'm -2 towards complete removal. I'm at least -1 towards
> shortening of the pause, as already indicated.

A 3s delay on boot doesn't even cause most people to notice.  The
infrastructure has failed at its intended purpose.

Therefore, we should consider now to replace this largely-failed
experiment with something better.

Personally, I think ARM is abusing this in the first place.  Adding a 3
second delay for someone who's explicitly chosen hmp_unsafe is petty. 
So is adding a 3 second delay for anyone who's explicitly chosen a
non-default configuration.  In retrospect, I think the delay for hvm_fep
is also wrong, especially as we also have a taint for it.

The *only* way to make users deal with the warnings is to surface them
very obviously in the UI they use to interact with their Xen system. 
That is XenCenter/XenOrchestra/virt-manager/etc, and possibly the SSH
MOTD - not a logfile that approximately noone reads.

To make this happen, warnings need to be available somewhere which isn't
the dmesg ring.  hypfs would be the obvious candidate at the moment.




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