Hello all,

I wonder how a given major number is assigned to a certain driver in kernel code? I.e. where can I read which routine of drivers code corresponds to which major number?

Are you talking about device major numbers or what?

Yes, about device major numbers.

http://www.kernel.org/pub/linux/docs...vices-2.6+.txt

is that what you are after?

Well, rather no than yes. You are right pointing to a document where these major numbers are listed and explained. But I need to know, in which file/part of kernel code these numbers are resolved? I mean what procedure tells kernel that if it gets a call with a device major number 9, it should activate the driver for either SCSI tape or RAID metadisk devices according to that listing? There must exist a table for correspondances between major numbers and their handlers like it is with syscalls and their handlers in entry.S (sys_call_table). Hope it's clear now.

In a running system, the major numbers in use can be seen using:

cat /proc/devices

The major numbers are used in the /dev/ entries. Therefore, opening a /dev entry causes the major number to select the associated driver.

The major numbers are registered by the driver when the driver is loaded. Some major numbers are hard-coded by the driver and some can be dynamically allocated by the kernel but then needs dynamically allocated /dev entries.

Try greping the Linux driver source code for the #define MAJOR