Re: 2.5.51 won't boot with devfs enabled

[Helge Hafting <helgehaf@aitel.hist.no>]

Eric Buddington wrote:
> 
> With 2.5.51 (gcc-3.2, Athlon, mostly modules, DEVFS=y, DEVFS_DEBUG=y),
> boot panics with "VFS: Cannot open root device "hda1" or
> 03:01".
> 
> I had the same problem with 2.5.50, avoidable by disabling devfs entirely.
> 
> -Eric
> -
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Booting anything later than 2.5.48 with devfs configured
either needs an extra kernel parameter, or a code change.  
Something broke when do_mounts.c were reorganized.
It doesn't matter wether devfs is used or not, as long as it
is configured.  

The lilo solution:
lilo tend to have a "root=/dev/hda1" or similiar.
This gets converted to "root=0301" on the kernel command line.
(Look at dmesg after a successful boot)

But this don't work for some reason when devfs is configured.
Use the following:

append="root=/dev/hda1"

to solve the problem.  This isn't converted to numbers and works.
Of course if you use auto-mounted devfs then you don't
have a /dev/hda1 but a /dev/ide/host0/bus0/target0/lun0/part1
instead.  If so, use that as root instead. You still have
to use the append= trick.

The code solution:
Edit init/do_mounts.c
Remove the following lines from the beginning of
the function prepare_namespace:
#ifdef CONFIG_DEVFS_FS
        sys_mount("devfs", "/dev", "devfs", 0, NULL);
        do_devfs = 1;
#endif
Then recompile, and the kernel should work with any lilo setup that
worked for 2.5.47 and earlier.  At least it worked for the setups
I tried.

This has no effect on kernels without devfs, and helps for kernels
comiled with devfs wether devfs is used or not.
I posted a patch for this, but there were no interest at all.


Helge Hafting