# Hotplug!?!

## pinzi

Hello

i want to know if the hotplug are necessary with the kernel 2.6?

If i don't install it my usb mouse don't work. But if i install it the mouse work but at the start up the sys tell me that the module mousedev are missing.

The module mousedev are still present in kernel 2.6? If this is true which kernel option build it when i recompile the kernel?

Greetings from Pinzi.

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## ozonator

Hotplug isn't necessary in 2.6, just as it wasn't necessary in 2.4.  (In fact, using hotplug with 2.6.1, my bluetooth dongle and gphoto2 don't work, so I'm running without it, no problem.)  The module name, however, might be different:  mousedev now has sub-options for different kinds of mice.

Assuming you've compiled the right modules with your kernel, what kind of mouse do you have?  If it's a PS/2 mouse, the module is called psmouse.  If it's a USB mouse, it's called hid.  If it's a serial mouse, it's called sermouse.  Try loading one with modprobe, and see if your mouse works then.  If it does, you can put that module into /etc/modules.autoload.d/kernel-2.6.

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## ett_gramse_nap

While we're on the topic of hotplug, could someone explain the whole concept about it or just post some links regarding hotplug.

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## Viha

Hotplug as a concept means just the ability to insert and remove devices at run time, dynamically loading/unloading the needed drivers.

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## !db!

I'll add to this ...

I have gentoo-sources-r2 and compiled in hotplug (at the time, I asked myself 'why not? might be useful in the future). I also have pcmcia compiled in and a funny thing happens at boot: I get warning messages that eth0 is already up when pcmcia starts. Now, I've searched this issue on the Forum quite a bit, and it seems that hotplug and pcmcia are 'racing' to start hardware at boot - hotplug seems to get there first ... Now, they're only warnings and everything works, but I gotta ask the question: what really would I loose if I compiled the kernel without hotplug? I don't really use my USB ports (for now) anything else?

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## ozonator

 *!db! wrote:*   

> I have gentoo-sources-r2 and compiled in hotplug (at the time, I asked myself 'why not? might be useful in the future). I also have pcmcia compiled in and a funny thing happens at boot: I get warning messages that eth0 is already up when pcmcia starts. Now, I've searched this issue on the Forum quite a bit, and it seems that hotplug and pcmcia are 'racing' to start hardware at boot - hotplug seems to get there first ... Now, they're only warnings and everything works, but I gotta ask the question: what really would I loose if I compiled the kernel without hotplug? I don't really use my USB ports (for now) anything else?

 

Given the situation you describe, chances are, you wouldn't lose anything you'd miss.  With a hotplug-enabled kernel, I have a machine that will (a) insert the right modules, if they're not already present, when I connect a hotpluggable devices, and (b) possibly do something appropriate (e.g. run a script) depending on what I've done.  An example of (a) is easy to think of; plug in a flash reader, and usb-storage will be loaded.  As for (b), that's handy with gphoto2; plug in the camera, and hotplug can give the resulting device appropriate permissions for me to use it (i.e., I don't have to be root).

Without hotplug, I just make sure I load all the modules I need, either manually, or with modules.autoload; or, just compile the device support I need into the kernel.  Beyond that, the only thing I miss is the permissions thing for gphoto2, but that's not a big problem, since I can easily run as root on my box.  Maybe another way to put this:  hotplug doesn't affect whether or not your devices work, but only how automatically they work and/or are configured when they're attached.

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## ozonator

Hmmm.  I may have spoken too quickly about the need for hotplug:  if you use pcmcia, you may need hotplug, as suggested in this post.  I don't have any machine with pcmcia, so this isn't something I've run into, or been able to test.  So, if you need pcmcia, you should likely look into its exact kernel requirements before trying a kernel without hotplug.

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## pinzi

I have installed the hotplug and when the sys start it load the the modules for the usb mouse:

ehci_hcd   

ohci_hcd   

uhci_hcd     

hid            

usbcore           

but after that it say me that the module mousedev is missing. Anyway the system start and the usb mouse work correctly! 

What's the problem?

N.B. I work with the kernel 2.6.0

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## ozonator

 *pinzi wrote:*   

> I have installed the hotplug and when the sys start it load the the modules for the usb mouse:
> 
> ehci_hcd   
> 
> ohci_hcd   
> ...

 

In 2.4, mousedev was needed, but it isn't in 2.6.  Do you have mousedev listed in /etc/modules.autoload.d/kernel-2.6?  Also, what version of hotplug are you running?  One more thought: try running 'modules-update', if you haven't already.

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## Mark Clegg

hotplugging loads the mousedev and input modules on startup if you have X11_USBMICE_HACK set to true in /etc/conf.d/usb Set it to false and see what happens, it works for me.

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## pjp

Moved from Installing Gentoo.

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