Bug#792910: "modprobe: module css:t0 not found in modules.dep" issued during boot

[Ben Hutchings <ben@decadent.org.uk>]

Control: retitle -1 Module aliases should be resolved at build time

On Sun, 19 Jul 2015 22:01:06 -0400 (EDT) Stephen Powell <zlinuxman@wowway.com> wrote:
> Package: initramfs-tools
> Version: 0.120
> Severity: minor
> 
> During boot of a jessie system on the s390x platform, I noticed the
> following error message on the console:
> 
> Begin: Loading essential drivers ...
> modprobe: module css:t0 not found in modules.dep
> 
> The error didn't seem to affect the ability of the system to boot,
> but I decided to investigate.  I traced the problem to the
> sys_walk_modalias function in /usr/share/initramfs-tools/hook-functions.
> The relevant code goes something like this:
> 
>    if [ -n "${modalias}" ]; then
>            force_load "${modalias}"
>    fi
> 
> The problem here is that the code does not distinguish between a regular
> module alias and what I call a udev alias.  (I'm not sure what the proper
> terminology is.  If you know please tell me.)

They're both module aliases.  The ones with colons in are generated at
kernel build time from the device ID tables in each module and at run-
time from the discovered device information.  Although udev handles the
uevents, it's always kmod that matches aliases against the installed
modules.

The specific problem here is that the driver that matches the module
alias 'css:t0' is ccw_device, which is built-in.

[...]
> Most of the udev aliases have asterisks in them.  All of them seem to have
> a colon in them.  I suggest the following code to replace the above:
> 
>    case "${modalias}" in
>            ""|*:*)
>                    :
>                    ;;
>            *)
>                    force_load "${modalias}"
>                    ;;
>    esac
> 
> The attached patch file fixes the problem on my system.

I think this is the wrong approach.  I don't think its make sense to
include *any* module aliases in /conf/modules; only the actual modules
should be listed there.

Ben.

-- 
Ben Hutchings
I'm always amazed by the number of people who take up solipsism because
they heard someone else explain it. - E*Borg on alt.fan.pratchett

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