[pocket-linux] Libc.so.6 problems in Chapter 3: Maybe a solution

[David Horton]

Benoît Depaire wrote:
> On 6/6/05, David Horton <dhorton at speakeasy.net> wrote:
>>Benoît Depaire wrote:
>>>Hi everybody,
>>>
>>>I've been working with the pocket linux guide for a couple of weeks
>>>now, and have been stuck lately at chapter 3. I got the well known
>>>boot problem with the c library (the shared library was not found).
>>>
>>>I've been looking for a solution, reading the previous mails on this
>>>mailing list. Ofcourse, I could have just passed this problem and go
>>>on with chapter 4 (using the available images), but I wanted to
>>>understand why my approach was failing.  After quite some testing, I
>>>might have an idea what the problem is and decided that I know enough
>>>now to proceed. However, not sure if my solution will or if I found
>>>the real reason for the problem (I am planning to check this in the
>>>future), I still want to share my thoughts with the rest.
>>>
>>>In another conversation on this topic, David Horton mentioned the
>>>possible problem was the fact that the used c library was build for a
>>>i686 and it was used on a i386 machine. However, another person (sorry
>>>forgot the name, and too lazy to look it up), mentioned the disks
>>>didn't work either on the original machine used to build the disks
>>>(and from which libc was taken).
>>>
>>>However, I suspect that the problem is somewhere in the same line. I
>>>suspect that the library is not "found" because it was build against a
>>>different kernel than that used on the bootdisk. Let me tell you why I
>>>think so:
>>>
>>>I created a new partition on my laptop (which i use to build the
>>>boot/root disks) and copied the rootdisk to this partition. Next I
>>>copied the vmlinuz (for i386 machine, taken from the bootdisk image
>>>available at the pocket linux website) to the boot directory, where
>>>the other kernels of this machine are located. Finally, I added a new
>>>entry in the lilo.conf file. When rebooting the machine, choosing to
>>>load the pocket linux kernel, it failed exactly the same way as on the
>>>machine I use the disks on. Thus, the type of machine (laptop =
>>>pentium M 1500mhz, other machine = desktop= pentium II 233 i believe)
>>>can not be the reason.
>>>
>>>Next I changed the pocket linux kernel in my boot directory with the
>>>original kernel working on this laptop. Now, the booting process looks
>>>pretty much the same, but now the bash shell shows up. Therefore, I
>>>believe the problem has something to do with the kernel-libc
>>>combination.
>>>
>>>Another indication is a certain parameter, that can be set during the
>>>compilation of glibc.
>>>
>>>`--enable-kernel=version'
>>>    This option is currently only useful on Linux systems. The version
>>>parameter should have the form X.Y.Z and describes the smallest
>>>version of the Linux kernel the generated library is expected to
>>>support. The higher the version number is, the less compatibility code
>>>is added, and the faster the code gets. '
>>>
>>>Now, you must now that I'm running a Mandrake 10.0 distro, so I can
>>>easily believe that my c library is optimized for my kernel and fails
>>>to work with older kernels, which i believe the kernel on the boot
>>>disk image clearly is.
>>>
>>>To be sure this is the real cause, one should compile the gnu c
>>>libraries (glibc) for the older kernel and see if that works. However,
>>>because compiling the gnu c libraries for another system than the host
>>>system, seems rather complicated, I postpone this thill after the
>>>pocket linux experience :).
>>>
>>>Finally I would like to mention that the program library how-to on the
>>>linux documentation project was a great help in understanding how the
>>>libraries work. I could recommend this reading to anybody who wants to
>>>know how linux finds the shared libraries.
>>>
>>>Cheers,
>>>Benoît
>>>
>>>PS: An idea i had lately, maybe interesting as addition to the pocket
>>>linux guide. Maybe it's possible to use the gmailfs (gmail account as
>>>file system) together with pocket linux
>>>
>>>_______________________________________________
>>>Pocket-Linux mailing list
>>>Pocket-Linux at ufo.chicago.il.us
>>>http://ufo.chicago.il.us/cgi-bin/mailman/listinfo/pocket-linux
>>
>>I think your advice about kernel-libc versions is very good.  The
>>"--enable-kernel=version" may very well be the key.  It seems logical
>>that distro makers might choose speed over compatibility when compiling
>>glibc.
>>
>>By the way, what version of kernel source are you using compared to the
>>kernel supplied with Mandrake?  Are they drasticly different?  For
>>example, 2.4 vs. 2.6 or is it just a minor difference?
>>
>>Dave
>>
>>
>>_______________________________________________
>>Pocket-Linux mailing list
>>Pocket-Linux at ufo.chicago.il.us
>>http://ufo.chicago.il.us/cgi-bin/mailman/listinfo/pocket-linux
>>
> 
> The mandrake kernel is 2.6.3-7 (for i686). The other kernel (which
> works) is the one on the bootdisk image supplied at
> pocket-linux.sourceforge.net. I don't know what version that is. I
> can't simply copy uname to the rootdisk, because it needs a higher
> version of libc, than the one from the working rootdisk image. But I
> hope you have an idea what version of kernel there is on the bootdisk?
> 
> Benoît
> 

The kernel on the diskette images is 2.4.something.  I think the version
is displayed at boot time or if you run dmesg.

Dave