2006-03-24 05:03:06

by L A Walsh

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Subject: Security downgrade? CONFIG_HOTPLUG required in 2.6.16?

I had this config'ed out in 2.6.15 for machine that didn't have
any hotpluggable devices. It is also configured with all the
modules it needs and has kernel-module loading disabled.

What has changed in 2.6.16 that my "static" machine now
needs hotplugging? As I understand it, hotplugging requires
application-level support code (in /etc/) and a special
application level "demon" to run in order to support these
requests.

I'd prefer my kernel not to be dependent on a run-time demon
to load "arbitrary" (user defined) segments of code that could
come from any source -- usually outside the vanilla kernel tree.

If I don't want a specific kernel or machine to be dynamically
reconfigurable after boot, why do I need to build in a mechanism for
runtime loading of modules?

Linda


2006-03-25 18:54:50

by Jan Engelhardt

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Subject: Re: Security downgrade? CONFIG_HOTPLUG required in 2.6.16?

>
> I had this config'ed out in 2.6.15 for machine that didn't have
> any hotpluggable devices. It is also configured with all the
> modules it needs and has kernel-module loading disabled.
>

Do you use swsusp?


Jan Engelhardt
--

2006-03-25 19:26:38

by Adrian Bunk

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Subject: Re: Security downgrade? CONFIG_HOTPLUG required in 2.6.16?

On Thu, Mar 23, 2006 at 09:03:03PM -0800, Linda Walsh wrote:
> I had this config'ed out in 2.6.15 for machine that didn't have
> any hotpluggable devices. It is also configured with all the
> modules it needs and has kernel-module loading disabled.
>
> What has changed in 2.6.16 that my "static" machine now
> needs hotplugging? As I understand it, hotplugging requires
> application-level support code (in /etc/) and a special
> application level "demon" to run in order to support these
> requests.
>
> I'd prefer my kernel not to be dependent on a run-time demon
> to load "arbitrary" (user defined) segments of code that could
> come from any source -- usually outside the vanilla kernel tree.
>
> If I don't want a specific kernel or machine to be dynamically
> reconfigurable after boot, why do I need to build in a mechanism for
> runtime loading of modules?

- hotplugging devices != module loading
- CONFIG_HOTPLUG does not load any code into the kernel.
- hotplugging devices can work without any userspace support

As an example, hotplugging an USB hard disk works fine with
CONFIG_MODULES=n and without any userspace support (assuming
a static /dev).

> Linda

cu
Adrian

--

"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed

2006-03-26 09:43:14

by L A Walsh

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Subject: Re: Security downgrade? CONFIG_HOTPLUG required in 2.6.16?

Adrian Bunk wrote:
> - hotplugging devices != module loading
> - CONFIG_HOTPLUG does not load any code into the kernel.
> - hotplugging devices can work without any userspace support
>
> As an example, hotplugging an USB hard disk works fine with
> CONFIG_MODULES=n and without any userspace support (assuming
> a static /dev).
>
---
Ah, I see. But if I have no USB hard disk to plug in?
Should I still be compiling in HOTPLUG? Seems a waste.
Thanks for the example though...

-linda

2006-03-26 10:11:10

by L A Walsh

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Subject: Re: Security downgrade? CONFIG_HOTPLUG required in 2.6.16?

Jan Engelhardt wrote:
> Do you use swsusp?
>
---
Nep. It's acting as a server :-). It's also SMP, does
that work with SWSUSP? Guess it has to now that laptops
have dual CPU's. In fact that that makes me wonder: how well
do the SMP laptops do power management under linux? Back
when I had a dual boot laptop, I seem to remember linux getting
about 25-33% more uptime.

-l

2006-03-26 19:32:10

by Jim Crilly

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Subject: Re: Security downgrade? CONFIG_HOTPLUG required in 2.6.16?

On 03/26/06 01:42:36AM -0800, Linda Walsh wrote:
> Adrian Bunk wrote:
> >- hotplugging devices != module loading
> >- CONFIG_HOTPLUG does not load any code into the kernel.
> >- hotplugging devices can work without any userspace support
> >
> >As an example, hotplugging an USB hard disk works fine with
> >CONFIG_MODULES=n and without any userspace support (assuming
> >a static /dev).
> >
> ---
> Ah, I see. But if I have no USB hard disk to plug in?
> Should I still be compiling in HOTPLUG? Seems a waste.
> Thanks for the example though...
>
> -linda

But what about USB keyboards and mice? IIRC at least some of the newer
servers where I work don't come with PS/2 ports anymore.

Jim.

2006-03-30 21:45:15

by L A Walsh

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Subject: Re: Security downgrade? CONFIG_HOTPLUG required in 2.6.16?

Jim Crilly wrote:
> But what about USB keyboards and mice? IIRC at least some of the newer
> servers where I work don't come with PS/2 ports anymore.
>
---
I have basic USB serial-I/O support built-in to my kernel:
it needs to monitor a USB-based UPS. Would a keyboard/mouse
require more support than to simply be compiled in?

I had a laptop that only had a 10Mb-ethernet built-in.
When it became a few years old, I switched to using a PCMCIA
card for 100Mb-ethernet. I never used the laptop's internal
port anymore but always used the pluggable card. PCMCIA was
still outside the kernel then, so my quick & easy solution was
to not compile in the 10BT device and use the in-kernel driver
for the 3com based 100BT card. I didn't need the "hot plugging"
capabilities of PCMCIA -- the kernel just called the new device
"eth0", and used it as a "permanent device".

If a computer uses USB I/O for basic console operations,
can't those drivers be statically built-in?

-linda