Re: [SLE] What does the 03:43 refer to?
From: Hartmut Meyer (hartmut.meyer_at_web.de)
Date: 02/28/04
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To: suse-linux-e@suse.com Date: Sat, 28 Feb 2004 17:37:41 +0100
Hi,
Am Samstag, 28. Februar 2004 16:45 schrieb Dylan:
> On Saturday 28 February 2004 00:44 am, Dr. David M. Colburn wrote:
> > "Kernel Panic VFS Unable to mount root fs on 03:43"
>
> OK, 03:43 refers to what?
The short answer is /dev/hdb3
To answer this question you need to know that both number (03 and 43) are
hexadecimal values. 03 hexadecimal is 3 decimal. 43 hexadecimal is 4*16+3
which is 67 in decimal notation.
Now have a look at the file /usr/src/linux/Documentation/devices.txt (you need
to have the kernel sources installed for that):
--- snip -----
3 block First MFM, RLL and IDE hard disk/CD-ROM interface
0 = /dev/hda Master: whole disk (or CD-ROM)
64 = /dev/hdb Slave: whole disk (or CD-ROM)
For partitions, add to the whole disk device number:
0 = /dev/hd? Whole disk
1 = /dev/hd?1 First partition
2 = /dev/hd?2 Second partition
...
63 = /dev/hd?63 63rd partition
For Linux/i386, partitions 1-4 are the primary
partitions, and 5 and above are logical partitions.
Other versions of Linux use partitioning schemes
appropriate to their respective architectures.
--- snap -----
If you have a look at the output of "ls -l /dev/hdb3":
brw-rw---- 1 root disk 3, 67 2003-09-23 19:59 /dev/hdb3
You will notice two things:
1. the leading 'b' marks this file as a block device file (in the devices.txt
file you will find that they differ between character and block devices)
2. Between "root disk" and the date you see "3, 67". The first one (3)
is the so called major device number, the second one (67) is the so called
minor device file.
If you try to access this device, the kernel will now that this is a IDE
harddisk or CD-ROM, because it is a block major 3 device file. It therefor
knows which driver to use in order to access the device. The minor device
number is used as an additional information for the driver. In this example
(harddisk) the driver will know which harddisk and partition to access.
Greetings from Bremen
hartmut
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