Skip to Main Content
Understanding the Linux Kernel
book

Understanding the Linux Kernel

by Daniel P. Bovet, Marco Cesati
October 2000
Intermediate to advanced content levelIntermediate to advanced
704 pages
18h 13m
English
O'Reilly Media, Inc.
Content preview from Understanding the Linux Kernel

Linking Modules on Demand

A module can be automatically linked when the functionality it provides is requested and automatically removed afterward.

For instance, suppose that the MS-DOS filesystem has not been linked, either statically or dynamically. If a user tries to mount an MS-DOS filesystem, the mount( ) system call normally fails by returning an error code, since MS-DOS is not included in the file_systems list of registered filesystems. However, if support for automatic linking of modules has been specified when configuring the kernel, Linux makes an attempt to link the MS-DOS module, then scans the list of registered filesystems again. If the module was successfully linked, the mount( ) system call can continue its execution as if the MS-DOS filesystem were present from the beginning.

The modprobe Program

In order to automatically link a module, the kernel creates a kernel thread to execute the /sbin/modprobe external program,[1] which takes care of possible complications due to module dependencies. The dependencies were already discussed earlier: a module may require one or more other modules, and these in turn may require still other modules. For instance, the MS-DOS module requires another module named fat containing some code common to all filesystems based on a File Allocation Table (FAT). Thus, if it is not already present, the fat module must also be automatically linked into the running kernel when the MS-DOS module is requested. Resolving dependencies and finding ...

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

Linux Kernel in a Nutshell

Linux Kernel in a Nutshell

Greg Kroah-Hartman
Linux Kernel Debugging

Linux Kernel Debugging

Kaiwan N. Billimoria
Understanding the Linux Kernel, 3rd Edition

Understanding the Linux Kernel, 3rd Edition

Daniel P. Bovet, Marco Cesati

Publisher Resources

ISBN: 0596000022Catalog PageErrata