Linode.com Forum

[zow]

So I'm poking around on my new Linode, just getting oriented, I do a `lsmod`, and get
Code:
Module                  Size  Used by    Not tainted
lsmod: QM_MODULES: Function not implemented

so I try the following
Code:
(none):/etc# modprobe -l
modprobe: Can't open dependencies file /lib/modules/2.4.22-linode9-3um/modules.dep (No such file or directory)

so I look in /lib/modules only to find it empty!

Now it's been a while since I've futzed around with UML or Debian (I've been using Mandrake on my desktop for a while now), so I'm wondering:

Do the Linodes use a monolithic kernel?
If not, where are the modules hiding? Is this some Debian specific behaviour?
And why doesn't lsmod work?


It's not terribly important (which is why I'm posting it here and not as a support ticket) -- just curious.

-"Zow"

[aaron]

zow wrote: So I'm poking around on my new Linode, just getting oriented, I do a `lsmod`, and get
Code:
Module                  Size  Used by    Not tainted
lsmod: QM_MODULES: Function not implemented


AFAIK, this is perfectly normal behaviour for a kernel compiled without module support.
zow wrote: so I try the following
Code:
(none):/etc# modprobe -l
modprobe: Can't open dependencies file /lib/modules/2.4.22-linode9-3um/modules.dep (No such file or directory)

so I look in /lib/modules only to find it empty!

as is this :P

zow wrote: Now it's been a while since I've futzed around with UML or Debian (I've been using Mandrake on my desktop for a while now), so I'm wondering:

Do the Linodes use a monolithic kernel?
It would appear so. UML itself seems to be able to use modules (according to the docs). I can think of a few reasons for doing this, mostly not requiring each user to add the modules to his own filesystem before booting a new kernel.

Personally, and I was just thinking about this before I read your question, I would like the ability to boot my own custom kernel, (granted, with the required UML patches and so on), since I don't have the need for a lot of the support that tends to be compiled in generic-for-everyone kernels. Could compiling my own kernel, and uploading it somewhere, and selecting it through the members control panel be a future option for linode?

[bjohnson]

aaron wrote:
Personally, and I was just thinking about this before I read your question, I would like the ability to boot my own custom kernel, (granted, with the required UML patches and so on), since I don't have the need for a lot of the support that tends to be compiled in generic-for-everyone kernels. Could compiling my own kernel, and uploading it somewhere, and selecting it through the members control panel be a future option for linode?

I would think that the security concerns of running your "program" on the host would be way to high to allow such a thing. Perhaps you can petition for a stripped down kernel...

[caker]

Module support is not compiled into Linode's UML kernels, as it would cause a security hole being able to insert code into the "process" on the host.

If you have specific requirements or patches, let me know and we can talk about building a custom kernel.

-Chris

[aaron]

caker wrote: If you have specific requirements or patches, let me know and we can talk about building a custom kernel.

Actually, I was just hoping for a stripped down kernel. I was going to ask what the current .config was, but /proc/kmem was kind enough to give it to me (since uml kernels store their config for use with the --showconfig command line option)

Anyway, I've put a modified (ie. very stripped - the resulting binary is about 1/2 the size) .config at http://parsed.net/config
I don't *think* I took out anything required.
It has ext3, ext2, devfs, loopback, and not much more.

[bji]

aaron wrote: Anyway, I've put a modified (ie. very stripped - the resulting binary is about 1/2 the size) .config at http://parsed.net/config
I don't *think* I took out anything required.
It has ext3, ext2, devfs, loopback, and not much more.

I would be very interested in using a stripped-down kernel as well.

[kenny]

bji wrote: aaron wrote: Anyway, I've put a modified (ie. very stripped - the resulting binary is about 1/2 the size) .config at http://parsed.net/config
I don't *think* I took out anything required.
It has ext3, ext2, devfs, loopback, and not much more.

I would be very interested in using a stripped-down kernel as well.

We should take a poll, I'd use it if it was kept up to date.

Kenny