Re: USB Hotplug??

Re: USB Hotplug??

[beolach]

Hey, Hal

Now that you've mastered USB Hotpluging, are you ready to start
hotswapping your CPU?

Just saw this on Slashdot /.

Links inside <>
<http://ask.slashdot.org/article.pl?sid=03/10/10/1336255&mode=thread&tid=106&tid=185>

<http://search.gmane.org/search.php?query=thoughts&email=&group=gmane.linux.kernel&sort=date>

I thought you might enjoy it. ;)
Conway S. Smith



-- Hal MacArgle <haltec@kvinet.com> wrote:
Greetings: I thought that "hotplug" merely meant a device could be
plugged in/out without shutting off the power to the computer..
Apparently there's more to it than that as I see a man and directory
dedicated to "hotplug."

I'm a bit lost at this point especially since I've plugged in a flash
drive, with the power off; noted the kernel finds it; changed the
default filesystem to ext2; and use it as a regular drive mounted as
/dev/sda1... So it's obvious that Slackware9.0/2.4.20 has configured
things to work right out of the box..

Seeing the hotplug directory and files I thought I might find an
answer to my basic query: Can the device actually be plugged in and
unplugged with the power on?? I read somewhere that firewire is
hotpluggable but "don't do it," in many cases.. No details.. I still
can't find the theory behind hot plugging.. As an EE you don't
connect anything to a live bus with impunity; unless the bus is
"dead" until it senses a load.. Maybe I can learn something here.
<grin>

Any comments? TIA & enjoying the list..

    Hal - in Terra Alta, WV - Slackware GNU/Linux 9.0   (2.4.20)
                Proprietary  Formats  Unacceptable
.
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USB Hotplug??

[Hal MacArgle]

Greetings: I thought that "hotplug" merely meant a device could be
plugged in/out without shutting off the power to the computer..
Apparently there's more to it than that as I see a man and directory
dedicated to "hotplug."

I'm a bit lost at this point especially since I've plugged in a flash
drive, with the power off; noted the kernel finds it; changed the
default filesystem to ext2; and use it as a regular drive mounted as
/dev/sda1... So it's obvious that Slackware9.0/2.4.20 has configured
things to work right out of the box..

Seeing the hotplug directory and files I thought I might find an
answer to my basic query: Can the device actually be plugged in and
unplugged with the power on?? I read somewhere that firewire is
hotpluggable but "don't do it," in many cases.. No details.. I still
can't find the theory behind hot plugging.. As an EE you don't
connect anything to a live bus with impunity; unless the bus is
"dead" until it senses a load.. Maybe I can learn something here.
<grin>

Any comments? TIA & enjoying the list..

    Hal - in Terra Alta, WV - Slackware GNU/Linux 9.0   (2.4.20)
                Proprietary  Formats  Unacceptable
.
-
To unsubscribe from this list: send the line "unsubscribe linux-newbie" in
the body of a message to majordomo@vger.kernel.org
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Re: USB Hotplug??

[Amichai Rotman]

On Sunday 05 October 2003 16:50, Hal MacArgle wrote:
> Seeing the hotplug directory and files I thought I might find an
> answer to my basic query: Can the device actually be plugged in and
> unplugged with the power on?? I read somewhere that firewire is
> hotpluggable but "don't do it," in many cases.. No details.. I still
> can't find the theory behind hot plugging.. As an EE you don't
> connect anything to a live bus with impunity; unless the bus is
> "dead" until it senses a load.. Maybe I can learn something here.
> <grin>
>
> Any comments? TIA & enjoying the list..

It would e wise if you umount the device before yanking it from the plug. 
Other than that - it is safe to unplug it while the power is on. If you 
unplug it before umounting it, the data on it will become unreadable / 
unaccessible and that's a shame... ;-)

Amichai. 

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Re: USB Hotplug??

[Hal MacArgle]

Greetings and thank you.. I crossed my fingers and tried it.. Awesome
to this old fella.. Wrote to module on one machine then hot plugged
it on another and read it.. Back to the original machine and it was
still there in all its glory.. I even tried it without proper umount
and it was still OK.. I wont do this as a practice of course. <grin>

Another nice tool for us to play with, eh?

Best,

Hal


On 10-05, Amichai Rotman wrote:
> 
> It would e wise if you umount the device before yanking it from the plug. 
> Other than that - it is safe to unplug it while the power is on. If you 
> unplug it before umounting it, the data on it will become unreadable / 
> unaccessible and that's a shame... ;-)
> 
> Amichai. 
> 
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Re: USB Hotplug??

[pa3gcu]

On Sunday 05 October 2003 16:50, Hal MacArgle wrote:
> Greetings: I thought that "hotplug" merely meant a device could be
> plugged in/out without shutting off the power to the computer..

Thats correct, thats what its for, just imagen having to turn off the power 
simply to connect a small camera then bootup retrive the pics' and reboot 
again so one could disconnect it.

"Hot plug" a nice word and a very good answer to the above, it means what it 
says.

> Apparently there's more to it than that as I see a man and directory
> dedicated to "hotplug."

It is rather complicated in its workings, however it does seem scary to say 
the lease.

>
> I'm a bit lost at this point especially since I've plugged in a flash
> drive, with the power off; noted the kernel finds it; changed the
> default filesystem to ext2; and use it as a regular drive mounted as
> /dev/sda1... So it's obvious that Slackware9.0/2.4.20 has configured
> things to work right out of the box..

Never tryed it like this, maybe i should, i cant see how a camera (i will take 
my camera) as an instance, how it can get assigned the ext2 filesystem when 
it is really a (fat16) filesystem.
Anyway, i cant really comment as i dont have the device here at the minute to 
try.

>
> Seeing the hotplug directory and files I thought I might find an
> answer to my basic query: Can the device actually be plugged in and
> unplugged with the power on?? I read somewhere that firewire is
> hotpluggable but "don't do it," in many cases.. No details.. I still
> can't find the theory behind hot plugging.. As an EE you don't
> connect anything to a live bus with impunity; unless the bus is
> "dead" until it senses a load.. Maybe I can learn something here.
> <grin>

I have plugged my camera in and out many times, it is none the worse for it 
and they as they say thats how it works.

What scares me is the new PCI hotplugging system. I suppose we (i at least) 
compare our presant day PCI devices to what the new systems are desinged for.
I know little if nothing of that new PCI hotpugging system so i will have to 
wait and see what the futcher brings.

On another note about developments, i was presented with a new 120Gig SATA 
device by a windows shop keeper who bet me i could not get it to work with 
linux, tommorrow i will inform him it does as i am using it now with a 
patched 2.4.22 kernel.

I can say they do work rather faster than a normal IDE device and it was not 
so hard to get it recocnised under linux, the problems start when one wants 
to install a distro on it, there's no support for thoses disks as yet.
I have slack-9.1 installed on it now.
If anyone is interested i will place a small howto on my site this week (i 
hope).

>
> Any comments? TIA & enjoying the list..

For what mine are worth, your welcome.

>
>     Hal - in Terra Alta, WV - Slackware GNU/Linux 9.0   (2.4.20)
>                 Proprietary  Formats  Unacceptable

-- 
If the Linux community is a bunch of theives because they
try to imitate windows programs, then the Windows community
is built on organized crime.

Regards Richard
pa3gcu@zeelandnet.nl
http://people.zeelandnet.nl/pa3gcu/



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Re: USB Hotplug??

[Hal MacArgle]

On 10-05, pa3gcu wrote:
> > Apparently there's more to it than that as I see a man and directory
> > dedicated to "hotplug."
> 
> It is rather complicated in its workings, however it does seem scary to say 
> the lease.
> 
> I have plugged my camera in and out many times, it is none the worse for it 
> and they as they say thats how it works.

Greetings: It does work and I tried it on two machines "sneaker
netting" a large file between a normal ATX type machine with it's
integral USB port and an older AT machine with it's retrofitted USB
set up.. Now I have to retrofit an USB extension to the front of the
cases, like the newer boxes.. <grin>



> On another note about developments, i was presented with a new 120Gig SATA 
> device by a windows shop keeper who bet me i could not get it to work with 
> linux, tommorrow i will inform him it does as i am using it now with a 
> patched 2.4.22 kernel.
> 
> I can say they do work rather faster than a normal IDE device and it was not 
> so hard to get it recocnised under linux, the problems start when one wants 
> to install a distro on it, there's no support for thoses disks as yet.
> I have slack-9.1 installed on it now.
> If anyone is interested i will place a small howto on my site this week (i 
> hope).

	I've been reading about the new serial drives with interest
because it may mean my sons, who must have the latest and greatest,
might be passing on to me their "old" 40-80Gb IDE drives, as they've
done in the past with the 2.1's and 4.3's... <grin> There is an
advantage to being behind the times, eh?

	I hope the vendor will let you keep the drive since you've
done the leg work.... And - Slack 9.1?? I haven't really started to
digest 9.0 yet. Ugh....

Vy 73,

    Hal - in Terra Alta, WV - Slackware GNU/Linux 9.0   (2.4.20)
                Proprietary  Formats  Unacceptable
.
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