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Re: sysmon_envsys(9)

On Sun, Aug 24, 2008 at 10:16:08PM +0000, Paul Goyette wrote:
> Several people have commented on various aspects of the current 
> sysmon_envsys(9) implementation and their desire to see it re-done for 
> NetBSD 5.0.  Many of these comments have been along the lines of "it 

No.  Definitely not for 5.0.  This is 6.0 stuff.

> started out good but just grew to be too unwieldly."
> I've been tasked with getting sysmon_envsys(9) back under control.  I'd 
> appreciate any specific examples of this "bloat", or suggestions about 
> what's wrong with, or lacking in, the current implementation.  Hopefully, 
> what I come up with will be more useable without any of the excess baggage.

While the API is probably better documented that the average kernel API,
its inner workings are less documented.  There are situations where it
is too clever for its own good:  for instance, it can get in the way of
a slow-access ACPI embedded controller.  We might have done better since
I last dared try it, but on one of my laptop I would get crashes or other
issues when running xbattbar because its queries added to the monitoring
thread in the kernel would either overwhelm the EC or more mundanely hit
locking bugs within ACPI-CA.  One thing this example shows is that
device drivers probably don't have enough control over how they can be
accessed through the current API.

Quentin Garnier - -
"See the look on my face from staying too long in one place
[...] every time the morning breaks I know I'm closer to falling"
KT Tunstall, Saving My Face, Drastic Fantastic, 2007.

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