Revisions to LDD3 Examples

The book Linux Device Drivers, 3rd Edition (LDD3), by Jonathan Corbet et al., contains a series of example kernel modules. Those examples have become obsolete, to the point of no longer even compiling, due to the many changes made to the Linux kernel since that book was written. Some of those changes are mentioned in Corbet's blog on API Changes in the 2.6 kernel, but the authors of the book have not updated the examples.

The last time this course was taught, I updated the examples from the LDD3 book to allow them to compile with Linux kernel 2.6.25. Those versions are posted here.

My intent this term is to further update the LDD3 examples, to kernel version 2.26.31. This Web page is intended to document my progress. Note: The file versions referred to here (e.g. as "compiles") have not yet been posted on the Web, as I am still working on them.

It is presented using the W3C "slidy" CSS style. Use the 'a' key to toggle between single page and slide modes. Use the right and left arrow keys to advance and back up.

Open Issues

Many of the examples will compile, but are no longer considered to be in good style. The following are some major changes that need to be made.

• Convert to use the bus-based model.
• Remove direct manipulations of task state. Look at file that include linux/sched.h
• nopage has gone away
• struct net_device has changed, no longer includes methods
• struct tty_driver has changed
• Examples are need of the use of read-copy-update, which has taken on greater importance

Changes

• Modules should no longer include linux/config.h. In some cases, other specific headers need to be included.
• Members "uid" etc., of struct task_struct moved to member cred, of type struct cred.
• kmem_cache_t is replaced by struct kmem_cache.
• struct work_struct replaced by struct delayed_work.
• aio methods changed, to use struct iovec.

Directory "scull"

File	Status
access.c	compiles Check use of TASK_INTERRUPTIBLE.
main.c	compiles
pipe.c	compiles
scull.h	compiles

Directory "scullc"

File	Status
main.c	compiles
mmap.c	compiles
scullc.h	compiles

Directory "sculld"

File	Status
main.c	compiles
mmap.c	Problem with nopage
sculld.h	compiles

Directory "scullp"

File	Status
main.c	compiles
mmap.c	Problem with nopage
scullp.h	compiles

Directory "scullv"

File	Status
main.c	compiles
mmap.c	Problem with nopage
scullv.h	compiles

Directories "include" and "lddbus"

File	Status
lddbus.h	compiles
lddbus.c	compiles

These need expansion to provide a true virtual bus, that can be used as the parent bus of the other pseudo-device modules, which then in turn need to be updated to use this bus.

Directory "misc-modules"

File	Status
complete.c
faulty.c
hello.c
hellop.c
jit.c
jiq.c
kdataalign.c
kdatasize.c
seq.c
silly.c
sleepy.c

Directory "misc-progs"

File	Status
asynctest.c
datasize.c
dataalign.c
inp.c
load50.c
mapcmp.c
mapper.c
netifdebug.c
nbtest.c
outp.c
polltest.c
setconsole.c
setlevel.c

Directory "pci"

File	Status
pci_skel.c	compiles

Directory "sbull"

File	Status
sbull.h	compiles
sbull.c	struct request has changed elv_next_request has gone away bio_cur_sectors has gone away end_request has gone away blk_queue_hardsect_size has gone away

Directory "short"

File	Status
short.c	compiles

Directory "shortprint"

File	Status
shortprint.c	compiles
shortprint.h	compiles

Directory "simple"

File	Status
simple.c	Problem with nopage

Directory "skull"

File	Status
skull_clean.c
skull_init.c

Directory "snull"

File	Status
snull.c	Problem with changes to struct net_device Missing declarations of netif_rx_complte and netif_rx_schedule
snull.h	compiles

Directory "tty"

File	Status
tiny_serial.c	A huge number of complation errors. Needs careful analysis.
tiny_tty.c	struct tty_driver has changed

Directory "usb"

File	Status
usb-skeleton.c	Missing function info, line 296