mdev with hda's
dhenderson at digital-pipe.com
Wed May 11 22:45:49 UTC 2011
On 05/11/2011 06:24 PM, Harald Becker wrote:
> Hallo David!
>> Since both are immediately exporting the environment, they will have
>> the same information as originally posted, but for the sake of
>> argument, I did as asked with the output below:
> Click! ... thinking about I found the possible solution why hd devices
> show up with a shell inherited environment ...
> ... the reason is contained in your above statement: hd and sd device do
> *not* both *immediately* export the environment ... I assume you are
> using a standard kernel, with statically included ata driver ... the
> kernel/device startup sequence differes between hd and sd devices. hd
> devices are present before init startup and do not produce hotplug
> events (as far as I noted). sd devices produce hotplug events on
> startup. That leads to the extreme difference of environment setup. hd
> devices are setup during initial "mdev -s" run ... and inherit the
> calling shells environment, whereas sd devices are initialized by
> hotplug events called from scsi kernel threads ... and inherit the
> kernel threads environment.
> ... that will explain all noted differences and behavior ... but may
> need some verification (only solved theoretically).
I'm actually using the TinyCore kernel (126.96.36.199) which includes a
couple of patches by their development team, so it's not a vanilla
kernel. Based on your explanation above, it makes perfect sense why I'm
getting two vastly different sets of environment variables. Problem
>> ADMAIL=support at XYZ.com
> Is this the environment setting of your startup / init script(s)?
> Especially the variables vga and bootmode are an indication for this
> May be you can search through your init scripts and locate the "mdev -s"
> call ... put an "env>/tmp/init_env" there (just before mdev call) and
> compare output with above list. Add an "export MDEV_TEST=irgendwas"
> bevor the "mdev -s", this shall show up as "MDEV_TEST=irgendwas" in your
> mdev output for hda devices ... if I'm right with my above theory.
> busybox mailing list
> busybox at busybox.net
Yes, the above is environment of the startup/init script - no need to
test that theory as I know for sure that's the case. :) I still think
that it would make more sense for mdev to pass a standard environment
when called than the way it works now. It will present less confusion
to a developer (namely me :).
NOTE: anyone using this thread as a resolution to a problem, your
environment variables will most likely *not* be like the ones above
since this is a custom distro.
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