Re: /dev before the root filesystem is mounted

[Jan Engelhardt <jengelh@linux01.gwdg.de>]

On Nov 13 2006 15:15, Ivan Ukhov wrote:
> i dont use initrd. the kernel understands argument 'root=/dev/...', so
> /dev should exist, mb not in a real filesystem, but just in ram or
> something. i just want to know what devices are available for being
> the root filesystem for the kernel (displaying all available devices
> will be enough for me).

/dev does not exist. How should it? The root filesystem / is empty, other
people can verify that, or you can verify it yourself with an
initramfs (which, unlike an initrd, is copied to / instead of being
mounted).

Yes, the kernel understands root=/dev/ but that's a hack, a strstr(s,
"/dev/"). Should you want to use, say, root=/devices/hda instead,
that would only succeed when using an initrd/initramfs.

To display the accepted block devices (this is most likely what you
really wanted), check out

ftp://ftp-1.gwdg.de/pub/linux/misc/suser-jengelh/kernel/linux-2.6.18-jen35/show_partitions.diff


Please (a) don't top post (b) don't strip Cc:s.

>
> 2006/11/13, Jan Engelhardt <jengelh@linux01.gwdg.de>:
>> 
>> > I want the kernel (2.4) to display (just using printk) all available
>> > devices with full path (/dev/...) before the root filesystem is
>> > mounted.
>> 
>> Case 1: You do not use an initrd/initramfs:
>> / is empty, /dev does not exist.
>> 
>> Case 2: You do use an initrd/initramfs
>> You populated /dev during creation of the initrd/initramfs image OR
>> your init script inside the initrd/initramfs mknods the nodes when run.
>> 
>> 
>>        -`J'
>> --
>> 
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	-`J'
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