Re: linux-2.6 install errors due to incompatible depmod files [was Re: Bug#518412: initramfs-tools: must support relative paths in modules.dep ]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, 2009-03-19 at 23:09 +0100, Frans Pop wrote:
> On Thursday 19 March 2009, Jon Masters wrote:
> > Yes, it was a bad idea of
> > mine (perhaps) to change the existing file format and I've learned
> > something, but it should only have affected for example that 3.4
> > release you're using.
> 
> Do you mean that earlier versions are not affected? Hasn't depmod 
> generated full paths basically any version up to 3.6?

Yes, it was 3.6 where it changed, not 3.4. However, there was a backward
compatibility issue during development that I was referring to. That
isn't the problem here anyway. The "problem" is that you want to use a
newly generated .dep file on an old install. I know that would be nice,
and I'm sorry that it bothers you, but at the same time you don't expect
newly built binaries to run against an older version of glibc they
weren't built against, etc.

> But even if it is only 3.4, that still makes it every Debian stable user 
> (and unknown other distros) who runs the risk of ending up with an 
> unbootable system for hard to trace reasons...

No, it really doesn't. If you upgrade to a new module-init-tools and run
depmod, then everything works. If you use the old .dep files then it
still works. If you force downgrade and don't rebuild your .dep files
then there certainly is the risk of being out of sync - but there are
other times where such things can happen too. I'm sure other utilities
have similar.

> Potentially painful for example for NAS devices where the kernel and 
> initrd get installed in flash, replacing the previous version.

Yes, and in that case there's no problem. If you do a forward upgrade
everything works just fine. It's only if you try to mix versions and go
backwards that you get a problem. I can see this in a cross-build setup
being a slight annoyance, but even there most people would use the same
version of the tools or expect to have problems building on a newer box
for an older release.

> As the kernel Makefile does run depmod during a build, I don't think it's 
> strange to assume users rely on that modules.dep being valid, even for 
> older versions of modprobe.

It works fine as long as your box is self-consistent. What is the actual
problem other than that mixing versions and trying to go backward
without quickly re-running depmod might cause module load problems?

> What exactly are the resons behind the change in file format that're so 
> strong that depmod cannot continue to generate the old format for the 
> next 5 years or so as a transition period

I guess it's called progress ;) Sarcasm aside, if you can give me an
example of an actual real life set of users who are adversely affected
then I'll try to do something to help out. But if you're asking for old
versions of software to be compatible with newer releases in every case
I think you're not being terribly realistic. The kernel changes to make
progress, and so do other utilities.

Jon.


--
To unsubscribe from this list: send the line "unsubscribe linux-modules" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

[Index of Archives]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Big List of Linux Books]

  Powered by Linux