[linux-dvb] Re: Kernel oops with ttusb_dec

[Olaf Titz <olaf@bigred.inka.de>]

> it's probably safer to use crc32_le() or crc32_be(), depends on which
> one exactly you need.

Good idea.

> Use a recent kernel, there crc32(), crc32_le() and crc32_be() are
> implemented as library functions.

Right, but the first cause of the problem was that modprobe sees
CIPE's crc32 definition exported where it surely should not.

> Enabling CONFIG_MODVERSIONS causes even more troubles, just browse the
> LinuxDVB mailing list archives, you'll find hundrets of mails where
> people failed to install standalone drivers just because they/their
> friends/their distributor didn't managed it to install matching kernel
> source, kernel config and kernel image.

It is _not possible_ to compile external modules without having
installed a matching kernel source/image. Period.

Perhaps they work sometimes or even most times, by accident. But in
CIPE I've stumbled over structures which shift their members around
depending on both obscure configuration options and compiler versions.
Flip a certain config switch, or use a different version of gcc than
the kernel was compiled with, and the module causes a 100%
reproducible kernel panic - I've seen (and found the reason for)
instances of both.

Without at least the complete kernel include tree from _exactly the
kernel build_ under which the module will be running, you have
absolutely no chance of compiling a reliable module. I wonder how many
of the OOPS reports found on this list are in fact due to this
mismatch.

Olaf



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