modules.dep and depmod.pl

modules.dep and depmod.pl

[Linus Walleij]

Hi,

what are other embedded developers experience with using the
script "depmod.pl" from BusyBox to create
installdir/lib/modules/<version>/modules.dep
during compile-time?
(It's this beast:
http://busybox.net/cgi-bin/viewcvs.cgi/trunk/busybox/examples/depmod.pl?rev=20447&view=markup

I tried this thing to be able to modprobe off a read-only flash
rootfilesystem and it "sort of" works, actually.

However there is no way you will pass this to the kernel DEPMOD
parameter, I only ever get this to work when doing it after
compilation, as a separate step.

Is there anyone beside me who would like to see this integrated
into scripts/ in the kernel to get some default modules.dep for
a read-only rootfs also when doing cross compilation, or am I
totally going down the wrong lane here?

Yours,
Linus Walleij

Re: modules.dep and depmod.pl

[Mike Frysinger]

On Fri, Jun 13, 2008 at 7:33 PM, Linus Walleij wrote:
> what are other embedded developers experience with using the
> script "depmod.pl" from BusyBox to create
> installdir/lib/modules/<version>/modules.dep
> during compile-time?

it's used in the uClinux distribution and works fine for me.  only had
problems when there are multiple kernel versions, but never had a
problem with a single.

> Is there anyone beside me who would like to see this integrated
> into scripts/ in the kernel to get some default modules.dep for
> a read-only rootfs also when doing cross compilation, or am I
> totally going down the wrong lane here?

seems like a worthwhile step to me
-mike

Re: modules.dep and depmod.pl

[Bernhard Fischer]

On Fri, Jun 13, 2008 at 07:45:58PM -0400, Mike Frysinger wrote:
>On Fri, Jun 13, 2008 at 7:33 PM, Linus Walleij wrote:

>> Is there anyone beside me who would like to see this integrated
>> into scripts/ in the kernel to get some default modules.dep for
>> a read-only rootfs also when doing cross compilation, or am I
>> totally going down the wrong lane here?
>
>seems like a worthwhile step to me

Using the perl-script to create a modules.dep is one option. If you do
not have a perl interpreter on your host, then you can build busybox'
recently added depmod for your host and use that to create a
modules.dep. Alternatively you can create a modules.dep via busybox on
the fly when booting.

Re: modules.dep and depmod.pl

[Dave Hylands]

Hi Linus,

> I tried this thing to be able to modprobe off a read-only flash
> rootfilesystem and it "sort of" works, actually.
>
> However there is no way you will pass this to the kernel DEPMOD
> parameter, I only ever get this to work when doing it after
> compilation, as a separate step.

I think it depends on which version of busybox you use.

When we were using 1.01 I think I had to patch the kernel Makefile. I
think I had to undo my patch when we upgraded to the  1.10 version of
busybox.

I'll have to wait until I get back to work on Monday to check.

> Is there anyone beside me who would like to see this integrated
> into scripts/ in the kernel to get some default modules.dep for
> a read-only rootfs also when doing cross compilation, or am I
> totally going down the wrong lane here?

You can also run the busybox depmod.pl after you've built the kernel,
but before you make the file system.

--
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/

Re: modules.dep and depmod.pl

[Linus Walleij]

2008/6/14 Dave Hylands <dhylands@gmail.com>:

> When we were using 1.01 I think I had to patch the kernel Makefile. I
> think I had to undo my patch when we upgraded to the  1.10 version of
> busybox.

OK I'll see if there is a newer version which is good for this.

> You can also run the busybox depmod.pl after you've built the kernel,
> but before you make the file system.

Yeah that's what I do currently....

Linus Walleij

Re: modules.dep and depmod.pl

[Matthieu castet]

Hi,

Linus Walleij <linus.ml.walleij <at> gmail.com> writes:

> 
> Hi,
> 
> what are other embedded developers experience with using the
> script "depmod.pl" from BusyBox to create
> installdir/lib/modules/≤version>/modules.dep
> during compile-time?
> (It's this beast:
>
http://busybox.net/cgi-bin/viewcvs.cgi/trunk/busybox/examples/depmod.pl?rev=20447&view=markup
> 
> I tried this thing to be able to modprobe off a read-only flash
> rootfilesystem and it "sort of" works, actually.
What's wrong with using your host depmod to build it.
When I build a crosscompilation kernel, and I do make module_install,
modules.dep are generated.






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Re: modules.dep and depmod.pl

[Linus Walleij]

2008/6/14 Matthieu castet <castet.matthieu@free.fr>:

> What's wrong with using your host depmod to build it.
> When I build a crosscompilation kernel, and I do make module_install,
> modules.dep are generated.

Well I do believe that works for you because you're lucky to
have a host with a recent kernel and module-init-tools.

However I believe that creates an unsound relation between the
host depmod and any cross compilation.

Currently I try to cross-compile a 2.6.25 kernel on an old good
workhorse with a 2.4.x kernel & likewise antique depmod. It
just won't work.

I tried to cross-compile all module-init-tools with --build=i386,
--host=i386, --target=arm-linux,
but that still fails: it checks what version of the kernel it's working
on, and determines that since that is a 2.4.x version it needs
to execute depmod.old instead :-P (Perhaps this is bug?)

I'd _really_ prefer cross-compilation to use the cross compiler
and in-kernel tools only, and currently I think it is actually
only depmod that deviates from that. (OK some scripts may
need a recent version of perl or so, that was just discussed in
another thread.)

Do you think an attempt to patch busybox:s depmod.pl into
scripts/ for the benefit of cross-compilation would be frowned
upon?

Linus Walleij