[Bug 627] modprobe-small: incorrect alias-based probe with dep_bb_fd < 0

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=627





--- Comment #4 from Jiri J. <jirij.jabb at gmail.com>  2009-09-27 05:20:19 UTC ---
First of all, yes, it's true that "find" has the same syndrome, but at least I
know why.

Let's assume I already have all modules in "modules" and "find modules/"
returns them in alphabetical (a->z) order.

I do the following:
mkdir mods0 mods1 mods2 mods3 mods4 mods5 mods6 mods7
cp -r modules/* mods0/.
cp -r mods0/* mods1/.
cp -r mods1/* mods2/.
cp -r mods2/* mods3/.
cp -r mods3/* mods4/.
cp -r mods4/* mods5/.
cp -r mods5/* mods6/.
cp -r mods6/* mods7/.

Modules in mods0 will be in reversed (z->a) order, while the a->z order will be
restored in mods1, broken in mods2, restored in mods3, etc.
I guess the alphabet doesn't even matter, the thing that matters is storage
order.

Since I can't reproduce it on my desktop OS, it's probably filesystem-specific.
The filesystem used here is tmpfs, however I've disabled shmem in the kernel
(EMBDEDDED->SHMEM), so it's in fact ramfs, as it says:

    The shmem is an internal filesystem used to manage shared memory.
    It is backed by swap and manages resource limits. It is also exported
    to userspace as tmpfs if TMPFS is enabled. Disabling this
    option replaces shmem and tmpfs with the much simpler ramfs code,
    which may be appropriate on small systems without swap.

Which might make sense, "cp" copies "a...." files as first and "z...." as last,
while the storage is done the other way, so "z...." is on the top.

I guess it shouldn't matter on an embedded system that much, modprobe-simple.c
seems to disagree with me.


Anyway,
> loads ata_generic.ko in both cases.
.. which is wrong.
I don't have any hardware ata_generic.ko might drive, moreover:

# grep 00007010 /mnt/lib/modules/2.6.29.6/modules.alias
alias pci:v00008086d00007010sv*sd*bc*sc*i* piix
alias pci:v00008086d00007010sv*sd*bc*sc*i* ata_piix


The funny thing is, that it works with modules.dep.bb generated from
reverse-ordered modules directory.

I'll post both my modprobe.dep.bb files (from both trees - generated by depmod
-n) as soon as possible.


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