Re: stretch: amd64, no dmesg when usb stuff plugged in
On Friday 06 September 2019 12:53:54 Charles Curley wrote:
> On Fri, 6 Sep 2019 10:44:45 -0400
>
> Gene Heskett <gheskett@shentel.net> wrote:
> > I found it. A staples brand usb hub that has served on the end of an
> > extension cable, as a place to plugin the dongles for the
> > keyboard/mouse for the last 8 or so years was doing funkity things
> > to udev. Replaced with another off brand slow hub with power buttons
> > for each socket, and the system is back to something resembling
> > normal operation.
>
> Good job.
>
> Here is what may be going on: the USB spec requires that plugs make .5
> amps (I think) available to devices. Hubs which do not use an external
> power supply cannot supply that to all the devices on that hub, so
> they do wonky things. So if you must have a USB hub, get one with an
> external power source.
It (the staples branded hub) has been running without external power for
5 or 6 years, with up to 2 keyboard/mouse dongles and a card writer
plugged in maybe 5% of that 5 or 6 years. And a fresh one, different
make, non-powered, is working just fine. I've no clue how much current
its drawing but I'd have to say under .2 amps based on the fact that its
generating no detectable heat. The one I took out had been making about
1 watts worth of heat that I had just noticed over the last couple of
months. I had also been losing that keyboard, and rarely the mouse too.
And I was blaming that on the kernel, but it did not get better
switching to the same kernel w/o the preempt-rt build, so next time I
reboot I'll go back to the preempt-rt version and tell the linuxcnc
developers I found the problem, if it doesn't recur in a week.
But I've no clue how long it will be before a buster compatible linuxcnc
comes out, some python stuff it depends on has been removed from buster,
requiring write-arounds.
Thanks Charles.
Cheers, Gene Heskett
--
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Genes Web page <http://geneslinuxbox.net:6309/gene>
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