Linux Device Drivers 3 examples

6 files changed, 1351 insertions, 0 deletions

diff --git a/snull/Makefile b/snull/Makefile
new file mode 100644
index 0000000..17949c1
--- /dev/null
+++ b/snull/Makefile
@@ -0,0 +1,41 @@
+# Comment/uncomment the following line to disable/enable debugging
+#DEBUG = y
+
+
+# Add your debugging flag (or not) to CFLAGS
+ifeq ($(DEBUG),y)
+  DEBFLAGS = -O -g -DSBULL_DEBUG # "-O" is needed to expand inlines
+else
+  DEBFLAGS = -O2
+endif
+
+CFLAGS += $(DEBFLAGS)
+CFLAGS += -I..
+
+ifneq ($(KERNELRELEASE),)
+# call from kernel build system
+
+obj-m	:= snull.o
+
+else
+
+KERNELDIR ?= /lib/modules/$(shell uname -r)/build
+PWD       := $(shell pwd)
+
+default:
+	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules
+
+endif
+
+
+
+clean:
+	rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions
+
+depend .depend dep:
+	$(CC) $(CFLAGS) -M *.c > .depend
+
+
+ifeq (.depend,$(wildcard .depend))
+include .depend
+endif
diff --git a/snull/SNULLO~1.CMD b/snull/SNULLO~1.CMD
new file mode 100755
index 0000000..f5d9303
--- /dev/null
+++ b/snull/SNULLO~1.CMD
@@ -0,0 +1,512 @@
+cmd_/media/hda3/desarrollo/kernel/examples/snull/snull.o := gcc -m32 -Wp,-MD,/media/hda3/desarrollo/kernel/examples/snull/.snull.o.d  -nostdinc -isystem /usr/lib/gcc/i486-linux-gnu/4.1.2/include -D__KERNEL__ -Iinclude  -include include/linux/autoconf.h -Iubuntu/include  -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -O2 -pipe -msoft-float -mregparm=3 -mpreferred-stack-boundary=2  -march=i586 -mtune=generic -ffreestanding -maccumulate-outgoing-args   -Iinclude/asm-i386/mach-default -fomit-frame-pointer -g  -fno-stack-protector -Wdeclaration-after-statement -Wno-pointer-sign -O2 -I..   -DMODULE -D"KBUILD_STR(s)=\#s" -D"KBUILD_BASENAME=KBUILD_STR(snull)"  -D"KBUILD_MODNAME=KBUILD_STR(snull)" -c -o /media/hda3/desarrollo/kernel/examples/snull/.tmp_snull.o /media/hda3/desarrollo/kernel/examples/snull/snull.c
+
+deps_/media/hda3/desarrollo/kernel/examples/snull/snull.o := \
+  /media/hda3/desarrollo/kernel/examples/snull/snull.c \
+  include/linux/module.h \
+    $(wildcard include/config/modules.h) \
+    $(wildcard include/config/modversions.h) \
+    $(wildcard include/config/unused/symbols.h) \
+    $(wildcard include/config/generic/bug.h) \
+    $(wildcard include/config/module/unload.h) \
+    $(wildcard include/config/kallsyms.h) \
+  include/linux/spinlock.h \
+    $(wildcard include/config/smp.h) \
+    $(wildcard include/config/debug/spinlock.h) \
+    $(wildcard include/config/preempt.h) \
+    $(wildcard include/config/debug/lock/alloc.h) \
+  include/linux/preempt.h \
+    $(wildcard include/config/debug/preempt.h) \
+  include/linux/thread_info.h \
+  include/linux/bitops.h \
+  include/asm/types.h \
+    $(wildcard include/config/highmem64g.h) \
+  include/asm/bitops.h \
+  include/linux/compiler.h \
+    $(wildcard include/config/enable/must/check.h) \
+  include/linux/compiler-gcc4.h \
+    $(wildcard include/config/forced/inlining.h) \
+  include/linux/compiler-gcc.h \
+  include/asm/alternative.h \
+    $(wildcard include/config/paravirt.h) \
+  include/linux/stddef.h \
+  include/linux/types.h \
+    $(wildcard include/config/uid16.h) \
+    $(wildcard include/config/lbd.h) \
+    $(wildcard include/config/lsf.h) \
+    $(wildcard include/config/resources/64bit.h) \
+  include/linux/posix_types.h \
+  include/asm/posix_types.h \
+  include/asm-generic/bitops/sched.h \
+  include/asm-generic/bitops/hweight.h \
+  include/asm-generic/bitops/fls64.h \
+  include/asm-generic/bitops/ext2-non-atomic.h \
+  include/asm-generic/bitops/le.h \
+  include/asm/byteorder.h \
+    $(wildcard include/config/x86/bswap.h) \
+  include/linux/byteorder/little_endian.h \
+  include/linux/byteorder/swab.h \
+  include/linux/byteorder/generic.h \
+  include/asm-generic/bitops/minix.h \
+  include/asm/thread_info.h \
+    $(wildcard include/config/4kstacks.h) \
+    $(wildcard include/config/debug/stack/usage.h) \
+  include/asm/page.h \
+    $(wildcard include/config/x86/use/3dnow.h) \
+    $(wildcard include/config/x86/pae.h) \
+    $(wildcard include/config/hugetlb/page.h) \
+    $(wildcard include/config/highmem4g.h) \
+    $(wildcard include/config/page/offset.h) \
+    $(wildcard include/config/flatmem.h) \
+    $(wildcard include/config/compat/vdso.h) \
+  include/asm-generic/pgtable-nopmd.h \
+  include/asm-generic/pgtable-nopud.h \
+  include/asm-generic/memory_model.h \
+    $(wildcard include/config/discontigmem.h) \
+    $(wildcard include/config/sparsemem.h) \
+    $(wildcard include/config/out/of/line/pfn/to/page.h) \
+  include/asm-generic/page.h \
+  include/asm/processor.h \
+    $(wildcard include/config/x86/ht.h) \
+    $(wildcard include/config/mk8.h) \
+    $(wildcard include/config/mk7.h) \
+  include/asm/vm86.h \
+    $(wildcard include/config/vm86.h) \
+  include/asm/ptrace.h \
+  include/asm/ptrace-abi.h \
+  include/asm/segment.h \
+  include/asm/math_emu.h \
+  include/asm/sigcontext.h \
+  include/asm/cpufeature.h \
+  include/asm/msr.h \
+  include/asm/paravirt.h \
+    $(wildcard include/config/x86/local/apic.h) \
+  include/linux/linkage.h \
+  include/asm/linkage.h \
+    $(wildcard include/config/x86/alignment/16.h) \
+  include/linux/stringify.h \
+  include/asm/system.h \
+    $(wildcard include/config/x86/cmpxchg64.h) \
+    $(wildcard include/config/x86/cmpxchg.h) \
+    $(wildcard include/config/x86/oostore.h) \
+  include/linux/kernel.h \
+    $(wildcard include/config/preempt/voluntary.h) \
+    $(wildcard include/config/debug/spinlock/sleep.h) \
+    $(wildcard include/config/printk.h) \
+    $(wildcard include/config/numa.h) \
+  /usr/lib/gcc/i486-linux-gnu/4.1.2/include/stdarg.h \
+  include/linux/log2.h \
+    $(wildcard include/config/arch/has/ilog2/u32.h) \
+    $(wildcard include/config/arch/has/ilog2/u64.h) \
+  include/asm/bug.h \
+    $(wildcard include/config/bug.h) \
+    $(wildcard include/config/debug/bugverbose.h) \
+  include/asm-generic/bug.h \
+  include/linux/irqflags.h \
+    $(wildcard include/config/trace/irqflags.h) \
+    $(wildcard include/config/trace/irqflags/support.h) \
+    $(wildcard include/config/x86.h) \
+  include/asm/irqflags.h \
+  include/linux/cache.h \
+  include/asm/cache.h \
+    $(wildcard include/config/x86/l1/cache/shift.h) \
+  include/linux/threads.h \
+    $(wildcard include/config/nr/cpus.h) \
+    $(wildcard include/config/base/small.h) \
+  include/asm/percpu.h \
+  include/asm-generic/percpu.h \
+  include/linux/cpumask.h \
+    $(wildcard include/config/hotplug/cpu.h) \
+  include/linux/bitmap.h \
+  include/linux/string.h \
+  include/asm/string.h \
+  include/linux/init.h \
+    $(wildcard include/config/hotplug.h) \
+    $(wildcard include/config/memory/hotplug.h) \
+    $(wildcard include/config/acpi/hotplug/memory.h) \
+    $(wildcard include/config/acpi/hotplug/memory/module.h) \
+  include/linux/bottom_half.h \
+  include/linux/spinlock_types.h \
+  include/linux/lockdep.h \
+    $(wildcard include/config/lockdep.h) \
+    $(wildcard include/config/generic/hardirqs.h) \
+    $(wildcard include/config/prove/locking.h) \
+  include/asm/spinlock_types.h \
+  include/asm/spinlock.h \
+    $(wildcard include/config/x86/ppro/fence.h) \
+  include/asm/atomic.h \
+    $(wildcard include/config/m386.h) \
+  include/asm-generic/atomic.h \
+  include/asm/rwlock.h \
+  include/linux/spinlock_api_smp.h \
+  include/linux/list.h \
+    $(wildcard include/config/debug/list.h) \
+  include/linux/poison.h \
+  include/linux/prefetch.h \
+  include/linux/stat.h \
+  include/asm/stat.h \
+  include/linux/time.h \
+  include/linux/seqlock.h \
+  include/linux/kmod.h \
+    $(wildcard include/config/kmod.h) \
+  include/linux/errno.h \
+  include/asm/errno.h \
+  include/asm-generic/errno.h \
+  include/asm-generic/errno-base.h \
+  include/linux/elf.h \
+  include/linux/auxvec.h \
+  include/asm/auxvec.h \
+  include/linux/elf-em.h \
+  include/asm/elf.h \
+  include/asm/user.h \
+  include/linux/utsname.h \
+    $(wildcard include/config/uts/ns.h) \
+  include/linux/sched.h \
+    $(wildcard include/config/detect/softlockup.h) \
+    $(wildcard include/config/split/ptlock/cpus.h) \
+    $(wildcard include/config/keys.h) \
+    $(wildcard include/config/bsd/process/acct.h) \
+    $(wildcard include/config/taskstats.h) \
+    $(wildcard include/config/inotify/user.h) \
+    $(wildcard include/config/schedstats.h) \
+    $(wildcard include/config/task/delay/acct.h) \
+    $(wildcard include/config/blk/dev/io/trace.h) \
+    $(wildcard include/config/cc/stackprotector.h) \
+    $(wildcard include/config/sysvipc.h) \
+    $(wildcard include/config/rt/mutexes.h) \
+    $(wildcard include/config/debug/mutexes.h) \
+    $(wildcard include/config/task/xacct.h) \
+    $(wildcard include/config/cpusets.h) \
+    $(wildcard include/config/compat.h) \
+    $(wildcard include/config/fault/injection.h) \
+  include/asm/param.h \
+    $(wildcard include/config/hz.h) \
+  include/linux/capability.h \
+  include/asm/current.h \
+  include/asm/pda.h \
+  include/linux/timex.h \
+    $(wildcard include/config/time/interpolation.h) \
+  include/asm/timex.h \
+    $(wildcard include/config/x86/elan.h) \
+  include/asm/tsc.h \
+    $(wildcard include/config/x86/tsc.h) \
+    $(wildcard include/config/x86/generic.h) \
+  include/linux/jiffies.h \
+  include/linux/calc64.h \
+  include/asm/div64.h \
+  include/linux/rbtree.h \
+  include/linux/nodemask.h \
+  include/linux/numa.h \
+    $(wildcard include/config/nodes/shift.h) \
+  include/asm/semaphore.h \
+  include/linux/wait.h \
+  include/linux/rwsem.h \
+    $(wildcard include/config/rwsem/generic/spinlock.h) \
+  include/asm/rwsem.h \
+  include/asm/mmu.h \
+  include/asm/cputime.h \
+  include/asm-generic/cputime.h \
+  include/linux/smp.h \
+  include/asm/smp.h \
+    $(wildcard include/config/x86/io/apic.h) \
+  include/asm/fixmap.h \
+    $(wildcard include/config/highmem.h) \
+    $(wildcard include/config/x86/visws/apic.h) \
+    $(wildcard include/config/x86/f00f/bug.h) \
+    $(wildcard include/config/x86/cyclone/timer.h) \
+    $(wildcard include/config/acpi.h) \
+    $(wildcard include/config/pci/mmconfig.h) \
+  include/asm/acpi.h \
+    $(wildcard include/config/acpi/sleep.h) \
+  include/acpi/pdc_intel.h \
+  include/asm/apicdef.h \
+  include/asm/kmap_types.h \
+    $(wildcard include/config/debug/highmem.h) \
+  include/asm/mpspec.h \
+  include/asm/mpspec_def.h \
+  include/asm-i386/mach-default/mach_mpspec.h \
+  include/asm/io_apic.h \
+  include/asm/apic.h \
+    $(wildcard include/config/x86/good/apic.h) \
+  include/linux/pm.h \
+    $(wildcard include/config/pm.h) \
+  include/asm-i386/mach-default/mach_apicdef.h \
+  include/linux/sem.h \
+  include/linux/ipc.h \
+    $(wildcard include/config/ipc/ns.h) \
+  include/asm/ipcbuf.h \
+  include/linux/kref.h \
+  include/asm/sembuf.h \
+  include/linux/signal.h \
+  include/asm/signal.h \
+  include/asm-generic/signal.h \
+  include/asm/siginfo.h \
+  include/asm-generic/siginfo.h \
+  include/linux/securebits.h \
+  include/linux/fs_struct.h \
+  include/linux/completion.h \
+  include/linux/pid.h \
+  include/linux/rcupdate.h \
+  include/linux/percpu.h \
+  include/linux/slab.h \
+    $(wildcard include/config/slab/debug.h) \
+    $(wildcard include/config/slab.h) \
+    $(wildcard include/config/debug/slab.h) \
+  include/linux/gfp.h \
+    $(wildcard include/config/zone/dma32.h) \
+  include/linux/mmzone.h \
+    $(wildcard include/config/force/max/zoneorder.h) \
+    $(wildcard include/config/arch/populates/node/map.h) \
+    $(wildcard include/config/flat/node/mem/map.h) \
+    $(wildcard include/config/have/memory/present.h) \
+    $(wildcard include/config/need/node/memmap/size.h) \
+    $(wildcard include/config/need/multiple/nodes.h) \
+    $(wildcard include/config/have/arch/early/pfn/to/nid.h) \
+    $(wildcard include/config/sparsemem/extreme.h) \
+    $(wildcard include/config/nodes/span/other/nodes.h) \
+  include/linux/memory_hotplug.h \
+    $(wildcard include/config/have/arch/nodedata/extension.h) \
+  include/linux/notifier.h \
+  include/linux/mutex.h \
+  include/linux/srcu.h \
+  include/linux/topology.h \
+    $(wildcard include/config/sched/smt.h) \
+    $(wildcard include/config/sched/mc.h) \
+  include/asm/topology.h \
+  include/asm-generic/topology.h \
+  include/linux/slab_def.h \
+  include/linux/kmalloc_sizes.h \
+    $(wildcard include/config/mmu.h) \
+    $(wildcard include/config/large/allocs.h) \
+  include/linux/seccomp.h \
+    $(wildcard include/config/seccomp.h) \
+  include/asm/seccomp.h \
+  include/linux/unistd.h \
+  include/asm/unistd.h \
+  include/linux/futex.h \
+    $(wildcard include/config/futex.h) \
+  include/linux/rtmutex.h \
+    $(wildcard include/config/debug/rt/mutexes.h) \
+  include/linux/plist.h \
+    $(wildcard include/config/debug/pi/list.h) \
+  include/linux/param.h \
+  include/linux/resource.h \
+  include/asm/resource.h \
+  include/asm-generic/resource.h \
+  include/linux/timer.h \
+  include/linux/hrtimer.h \
+    $(wildcard include/config/no/idle/hz.h) \
+  include/linux/ktime.h \
+    $(wildcard include/config/ktime/scalar.h) \
+  include/linux/task_io_accounting.h \
+    $(wildcard include/config/task/io/accounting.h) \
+  include/linux/aio.h \
+  include/linux/workqueue.h \
+  include/linux/aio_abi.h \
+  include/linux/uio.h \
+  include/linux/sysdev.h \
+  include/linux/kobject.h \
+  include/linux/sysfs.h \
+    $(wildcard include/config/sysfs.h) \
+  include/linux/nsproxy.h \
+  include/asm/desc.h \
+  include/asm/ldt.h \
+  include/linux/moduleparam.h \
+  include/asm/local.h \
+  include/asm/module.h \
+    $(wildcard include/config/m486.h) \
+    $(wildcard include/config/m586.h) \
+    $(wildcard include/config/m586tsc.h) \
+    $(wildcard include/config/m586mmx.h) \
+    $(wildcard include/config/mcore2.h) \
+    $(wildcard include/config/m686.h) \
+    $(wildcard include/config/mpentiumii.h) \
+    $(wildcard include/config/mpentiumiii.h) \
+    $(wildcard include/config/mpentiumm.h) \
+    $(wildcard include/config/mpentium4.h) \
+    $(wildcard include/config/mk6.h) \
+    $(wildcard include/config/mcrusoe.h) \
+    $(wildcard include/config/mefficeon.h) \
+    $(wildcard include/config/mwinchipc6.h) \
+    $(wildcard include/config/mwinchip2.h) \
+    $(wildcard include/config/mwinchip3d.h) \
+    $(wildcard include/config/mcyrixiii.h) \
+    $(wildcard include/config/mviac3/2.h) \
+    $(wildcard include/config/mgeodegx1.h) \
+    $(wildcard include/config/mgeode/lx.h) \
+  include/linux/interrupt.h \
+    $(wildcard include/config/generic/irq/probe.h) \
+  include/linux/irqreturn.h \
+  include/linux/hardirq.h \
+    $(wildcard include/config/preempt/bkl.h) \
+    $(wildcard include/config/virt/cpu/accounting.h) \
+  include/linux/smp_lock.h \
+    $(wildcard include/config/lock/kernel.h) \
+  include/asm/hardirq.h \
+  include/linux/irq.h \
+    $(wildcard include/config/s390.h) \
+    $(wildcard include/config/irq/per/cpu.h) \
+    $(wildcard include/config/irq/release/method.h) \
+    $(wildcard include/config/generic/pending/irq.h) \
+    $(wildcard include/config/irqbalance.h) \
+    $(wildcard include/config/proc/fs.h) \
+    $(wildcard include/config/auto/irq/affinity.h) \
+    $(wildcard include/config/generic/hardirqs/no//do/irq.h) \
+  include/asm/irq.h \
+  include/asm-i386/mach-default/irq_vectors.h \
+  include/asm-i386/mach-default/irq_vectors_limits.h \
+  include/asm/irq_regs.h \
+  include/asm/hw_irq.h \
+  include/linux/profile.h \
+    $(wildcard include/config/profiling.h) \
+  include/asm/sections.h \
+  include/asm-generic/sections.h \
+  include/linux/irq_cpustat.h \
+  include/linux/device.h \
+    $(wildcard include/config/debug/devres.h) \
+  include/linux/ioport.h \
+  include/linux/klist.h \
+  include/asm/device.h \
+  include/linux/in.h \
+  include/linux/socket.h \
+  include/asm/socket.h \
+  include/asm/sockios.h \
+  include/linux/sockios.h \
+  include/linux/netdevice.h \
+    $(wildcard include/config/ax25.h) \
+    $(wildcard include/config/ax25/module.h) \
+    $(wildcard include/config/tr.h) \
+    $(wildcard include/config/net/ipip.h) \
+    $(wildcard include/config/net/ipip/module.h) \
+    $(wildcard include/config/net/ipgre.h) \
+    $(wildcard include/config/net/ipgre/module.h) \
+    $(wildcard include/config/ipv6/sit.h) \
+    $(wildcard include/config/ipv6/sit/module.h) \
+    $(wildcard include/config/ipv6/tunnel.h) \
+    $(wildcard include/config/ipv6/tunnel/module.h) \
+    $(wildcard include/config/netpoll.h) \
+    $(wildcard include/config/net/poll/controller.h) \
+    $(wildcard include/config/netpoll/trap.h) \
+    $(wildcard include/config/net/dma.h) \
+  include/linux/if.h \
+  include/linux/hdlc/ioctl.h \
+  include/linux/if_ether.h \
+    $(wildcard include/config/sysctl.h) \
+  include/linux/skbuff.h \
+    $(wildcard include/config/netfilter.h) \
+    $(wildcard include/config/bridge/netfilter.h) \
+    $(wildcard include/config/vlan/8021q.h) \
+    $(wildcard include/config/vlan/8021q/module.h) \
+    $(wildcard include/config/nf/conntrack.h) \
+    $(wildcard include/config/nf/conntrack/module.h) \
+    $(wildcard include/config/net/sched.h) \
+    $(wildcard include/config/net/cls/act.h) \
+    $(wildcard include/config/network/secmark.h) \
+  include/linux/net.h \
+  include/linux/random.h \
+  include/linux/ioctl.h \
+  include/asm/ioctl.h \
+  include/asm-generic/ioctl.h \
+  include/linux/sysctl.h \
+  include/linux/textsearch.h \
+  include/linux/err.h \
+  include/net/checksum.h \
+  include/asm/uaccess.h \
+    $(wildcard include/config/x86/intel/usercopy.h) \
+    $(wildcard include/config/x86/wp/works/ok.h) \
+  include/asm/checksum.h \
+  include/linux/in6.h \
+  include/linux/dmaengine.h \
+    $(wildcard include/config/dma/engine.h) \
+  include/linux/if_packet.h \
+  include/linux/etherdevice.h \
+  include/linux/ip.h \
+  include/linux/tcp.h \
+    $(wildcard include/config/tcp/md5sig.h) \
+  include/net/sock.h \
+    $(wildcard include/config/security/network.h) \
+    $(wildcard include/config/netdebug.h) \
+    $(wildcard include/config/net.h) \
+  include/linux/mm.h \
+    $(wildcard include/config/stack/growsup.h) \
+    $(wildcard include/config/debug/vm.h) \
+    $(wildcard include/config/shmem.h) \
+    $(wildcard include/config/ia64.h) \
+    $(wildcard include/config/debug/pagealloc.h) \
+  include/linux/prio_tree.h \
+  include/linux/fs.h \
+    $(wildcard include/config/dnotify.h) \
+    $(wildcard include/config/quota.h) \
+    $(wildcard include/config/inotify.h) \
+    $(wildcard include/config/security.h) \
+    $(wildcard include/config/epoll.h) \
+    $(wildcard include/config/auditsyscall.h) \
+    $(wildcard include/config/block.h) \
+    $(wildcard include/config/fs/xip.h) \
+    $(wildcard include/config/migration.h) \
+  include/linux/limits.h \
+  include/linux/kdev_t.h \
+  include/linux/dcache.h \
+  include/linux/namei.h \
+  include/linux/radix-tree.h \
+  include/linux/quota.h \
+  include/linux/dqblk_xfs.h \
+  include/linux/dqblk_v1.h \
+  include/linux/dqblk_v2.h \
+  include/linux/nfs_fs_i.h \
+  include/linux/nfs.h \
+  include/linux/sunrpc/msg_prot.h \
+  include/linux/fcntl.h \
+  include/asm/fcntl.h \
+  include/asm-generic/fcntl.h \
+    $(wildcard include/config/64bit.h) \
+  include/linux/debug_locks.h \
+    $(wildcard include/config/debug/locking/api/selftests.h) \
+  include/linux/backing-dev.h \
+  include/linux/mm_types.h \
+  include/asm/pgtable.h \
+    $(wildcard include/config/highpte.h) \
+  include/asm/pgtable-2level-defs.h \
+  include/asm/pgtable-2level.h \
+  include/asm-generic/pgtable.h \
+  include/linux/page-flags.h \
+    $(wildcard include/config/swap.h) \
+  include/linux/vmstat.h \
+    $(wildcard include/config/vm/event/counters.h) \
+  include/linux/security.h \
+    $(wildcard include/config/security/network/xfrm.h) \
+  include/linux/binfmts.h \
+  include/linux/shm.h \
+  include/asm/shmparam.h \
+  include/asm/shmbuf.h \
+  include/linux/msg.h \
+  include/asm/msgbuf.h \
+  include/linux/key.h \
+  include/linux/xfrm.h \
+  include/net/flow.h \
+    $(wildcard include/config/ipv6/mip6.h) \
+  include/linux/filter.h \
+  include/net/dst.h \
+    $(wildcard include/config/net/cls/route.h) \
+    $(wildcard include/config/xfrm.h) \
+  include/linux/rtnetlink.h \
+  include/linux/netlink.h \
+  include/linux/if_link.h \
+  include/linux/if_addr.h \
+  include/linux/neighbour.h \
+  include/net/neighbour.h \
+  include/linux/seq_file.h \
+  include/net/inet_connection_sock.h \
+  include/linux/poll.h \
+  include/asm/poll.h \
+  include/net/inet_sock.h \
+    $(wildcard include/config/ipv6.h) \
+    $(wildcard include/config/ipv6/module.h) \
+  include/net/request_sock.h \
+  include/net/inet_timewait_sock.h \
+  include/net/tcp_states.h \
+  include/net/timewait_sock.h \
+  /media/hda3/desarrollo/kernel/examples/snull/snull.h \
+
+/media/hda3/desarrollo/kernel/examples/snull/snull.o: $(deps_/media/hda3/desarrollo/kernel/examples/snull/snull.o)
+
+$(deps_/media/hda3/desarrollo/kernel/examples/snull/snull.o):
diff --git a/snull/snull.c b/snull/snull.c
new file mode 100644
index 0000000..6fbde81
--- /dev/null
+++ b/snull/snull.c
@@ -0,0 +1,736 @@
+/*
+ * snull.c --  the Simple Network Utility
+ *
+ * Copyright (C) 2001 Alessandro Rubini and Jonathan Corbet
+ * Copyright (C) 2001 O'Reilly & Associates
+ *
+ * The source code in this file can be freely used, adapted,
+ * and redistributed in source or binary form, so long as an
+ * acknowledgment appears in derived source files.  The citation
+ * should list that the code comes from the book "Linux Device
+ * Drivers" by Alessandro Rubini and Jonathan Corbet, published
+ * by O'Reilly & Associates.   No warranty is attached;
+ * we cannot take responsibility for errors or fitness for use.
+ *
+ * $Id: snull.c,v 1.21 2004/11/05 02:36:03 rubini Exp $
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+
+#include <linux/sched.h>
+#include <linux/kernel.h> /* printk() */
+#include <linux/slab.h> /* kmalloc() */
+#include <linux/errno.h>  /* error codes */
+#include <linux/types.h>  /* size_t */
+#include <linux/interrupt.h> /* mark_bh */
+
+#include <linux/in.h>
+#include <linux/netdevice.h>   /* struct device, and other headers */
+#include <linux/etherdevice.h> /* eth_type_trans */
+#include <linux/ip.h>          /* struct iphdr */
+#include <linux/tcp.h>         /* struct tcphdr */
+#include <linux/skbuff.h>
+
+#include "snull.h"
+
+#include <linux/in6.h>
+#include <asm/checksum.h>
+
+MODULE_AUTHOR("Alessandro Rubini, Jonathan Corbet");
+MODULE_LICENSE("Dual BSD/GPL");
+
+
+/*
+ * Transmitter lockup simulation, normally disabled.
+ */
+static int lockup = 0;
+module_param(lockup, int, 0);
+
+static int timeout = SNULL_TIMEOUT;
+module_param(timeout, int, 0);
+
+/*
+ * Do we run in NAPI mode?
+ */
+static int use_napi = 0;
+module_param(use_napi, int, 0);
+
+
+/*
+ * A structure representing an in-flight packet.
+ */
+struct snull_packet {
+	struct snull_packet *next;
+	struct net_device *dev;
+	int	datalen;
+	u8 data[ETH_DATA_LEN];
+};
+
+int pool_size = 8;
+module_param(pool_size, int, 0);
+
+/*
+ * This structure is private to each device. It is used to pass
+ * packets in and out, so there is place for a packet
+ */
+
+struct snull_priv {
+	struct net_device_stats stats;
+	int status;
+	struct snull_packet *ppool;
+	struct snull_packet *rx_queue;  /* List of incoming packets */
+	int rx_int_enabled;
+	int tx_packetlen;
+	u8 *tx_packetdata;
+	struct sk_buff *skb;
+	spinlock_t lock;
+};
+
+static void snull_tx_timeout(struct net_device *dev);
+static void (*snull_interrupt)(int, void *, struct pt_regs *);
+
+/*
+ * Set up a device's packet pool.
+ */
+void snull_setup_pool(struct net_device *dev)
+{
+	struct snull_priv *priv = netdev_priv(dev);
+	int i;
+	struct snull_packet *pkt;
+
+	priv->ppool = NULL;
+	for (i = 0; i < pool_size; i++) {
+		pkt = kmalloc (sizeof (struct snull_packet), GFP_KERNEL);
+		if (pkt == NULL) {
+			printk (KERN_NOTICE "Ran out of memory allocating packet pool\n");
+			return;
+		}
+		pkt->dev = dev;
+		pkt->next = priv->ppool;
+		priv->ppool = pkt;
+	}
+}
+
+void snull_teardown_pool(struct net_device *dev)
+{
+	struct snull_priv *priv = netdev_priv(dev);
+	struct snull_packet *pkt;
+    
+	while ((pkt = priv->ppool)) {
+		priv->ppool = pkt->next;
+		kfree (pkt);
+		/* FIXME - in-flight packets ? */
+	}
+}    
+
+/*
+ * Buffer/pool management.
+ */
+struct snull_packet *snull_get_tx_buffer(struct net_device *dev)
+{
+	struct snull_priv *priv = netdev_priv(dev);
+	unsigned long flags;
+	struct snull_packet *pkt;
+    
+	spin_lock_irqsave(&priv->lock, flags);
+	pkt = priv->ppool;
+	priv->ppool = pkt->next;
+	if (priv->ppool == NULL) {
+		printk (KERN_INFO "Pool empty\n");
+		netif_stop_queue(dev);
+	}
+	spin_unlock_irqrestore(&priv->lock, flags);
+	return pkt;
+}
+
+
+void snull_release_buffer(struct snull_packet *pkt)
+{
+	unsigned long flags;
+	struct snull_priv *priv = netdev_priv(pkt->dev);
+	
+	spin_lock_irqsave(&priv->lock, flags);
+	pkt->next = priv->ppool;
+	priv->ppool = pkt;
+	spin_unlock_irqrestore(&priv->lock, flags);
+	if (netif_queue_stopped(pkt->dev) && pkt->next == NULL)
+		netif_wake_queue(pkt->dev);
+}
+
+void snull_enqueue_buf(struct net_device *dev, struct snull_packet *pkt)
+{
+	unsigned long flags;
+	struct snull_priv *priv = netdev_priv(dev);
+
+	spin_lock_irqsave(&priv->lock, flags);
+	pkt->next = priv->rx_queue;  /* FIXME - misorders packets */
+	priv->rx_queue = pkt;
+	spin_unlock_irqrestore(&priv->lock, flags);
+}
+
+struct snull_packet *snull_dequeue_buf(struct net_device *dev)
+{
+	struct snull_priv *priv = netdev_priv(dev);
+	struct snull_packet *pkt;
+	unsigned long flags;
+
+	spin_lock_irqsave(&priv->lock, flags);
+	pkt = priv->rx_queue;
+	if (pkt != NULL)
+		priv->rx_queue = pkt->next;
+	spin_unlock_irqrestore(&priv->lock, flags);
+	return pkt;
+}
+
+/*
+ * Enable and disable receive interrupts.
+ */
+static void snull_rx_ints(struct net_device *dev, int enable)
+{
+	struct snull_priv *priv = netdev_priv(dev);
+	priv->rx_int_enabled = enable;
+}
+
+    
+/*
+ * Open and close
+ */
+
+int snull_open(struct net_device *dev)
+{
+	/* request_region(), request_irq(), ....  (like fops->open) */
+
+	/* 
+	 * Assign the hardware address of the board: use "\0SNULx", where
+	 * x is 0 or 1. The first byte is '\0' to avoid being a multicast
+	 * address (the first byte of multicast addrs is odd).
+	 */
+	memcpy(dev->dev_addr, "\0SNUL0", ETH_ALEN);
+	if (dev == snull_devs[1])
+		dev->dev_addr[ETH_ALEN-1]++; /* \0SNUL1 */
+	netif_start_queue(dev);
+	return 0;
+}
+
+int snull_release(struct net_device *dev)
+{
+    /* release ports, irq and such -- like fops->close */
+
+	netif_stop_queue(dev); /* can't transmit any more */
+	return 0;
+}
+
+/*
+ * Configuration changes (passed on by ifconfig)
+ */
+int snull_config(struct net_device *dev, struct ifmap *map)
+{
+	if (dev->flags & IFF_UP) /* can't act on a running interface */
+		return -EBUSY;
+
+	/* Don't allow changing the I/O address */
+	if (map->base_addr != dev->base_addr) {
+		printk(KERN_WARNING "snull: Can't change I/O address\n");
+		return -EOPNOTSUPP;
+	}
+
+	/* Allow changing the IRQ */
+	if (map->irq != dev->irq) {
+		dev->irq = map->irq;
+        	/* request_irq() is delayed to open-time */
+	}
+
+	/* ignore other fields */
+	return 0;
+}
+
+/*
+ * Receive a packet: retrieve, encapsulate and pass over to upper levels
+ */
+void snull_rx(struct net_device *dev, struct snull_packet *pkt)
+{
+	struct sk_buff *skb;
+	struct snull_priv *priv = netdev_priv(dev);
+
+	/*
+	 * The packet has been retrieved from the transmission
+	 * medium. Build an skb around it, so upper layers can handle it
+	 */
+	skb = dev_alloc_skb(pkt->datalen + 2);
+	if (!skb) {
+		if (printk_ratelimit())
+			printk(KERN_NOTICE "snull rx: low on mem - packet dropped\n");
+		priv->stats.rx_dropped++;
+		goto out;
+	}
+	skb_reserve(skb, 2); /* align IP on 16B boundary */  
+	memcpy(skb_put(skb, pkt->datalen), pkt->data, pkt->datalen);
+
+	/* Write metadata, and then pass to the receive level */
+	skb->dev = dev;
+	skb->protocol = eth_type_trans(skb, dev);
+	skb->ip_summed = CHECKSUM_UNNECESSARY; /* don't check it */
+	priv->stats.rx_packets++;
+	priv->stats.rx_bytes += pkt->datalen;
+	netif_rx(skb);
+  out:
+	return;
+}
+    
+
+/*
+ * The poll implementation.
+ */
+static int snull_poll(struct net_device *dev, int *budget)
+{
+	int npackets = 0, quota = min(dev->quota, *budget);
+	struct sk_buff *skb;
+	struct snull_priv *priv = netdev_priv(dev);
+	struct snull_packet *pkt;
+    
+	while (npackets < quota && priv->rx_queue) {
+		pkt = snull_dequeue_buf(dev);
+		skb = dev_alloc_skb(pkt->datalen + 2);
+		if (! skb) {
+			if (printk_ratelimit())
+				printk(KERN_NOTICE "snull: packet dropped\n");
+			priv->stats.rx_dropped++;
+			snull_release_buffer(pkt);
+			continue;
+		}
+		skb_reserve(skb, 2); /* align IP on 16B boundary */  
+		memcpy(skb_put(skb, pkt->datalen), pkt->data, pkt->datalen);
+		skb->dev = dev;
+		skb->protocol = eth_type_trans(skb, dev);
+		skb->ip_summed = CHECKSUM_UNNECESSARY; /* don't check it */
+		netif_receive_skb(skb);
+		
+        	/* Maintain stats */
+		npackets++;
+		priv->stats.rx_packets++;
+		priv->stats.rx_bytes += pkt->datalen;
+		snull_release_buffer(pkt);
+	}
+	/* If we processed all packets, we're done; tell the kernel and reenable ints */
+	*budget -= npackets;
+	dev->quota -= npackets;
+	if (! priv->rx_queue) {
+		netif_rx_complete(dev);
+		snull_rx_ints(dev, 1);
+		return 0;
+	}
+	/* We couldn't process everything. */
+	return 1;
+}
+	    
+        
+/*
+ * The typical interrupt entry point
+ */
+static void snull_regular_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+	int statusword;
+	struct snull_priv *priv;
+	struct snull_packet *pkt = NULL;
+	/*
+	 * As usual, check the "device" pointer to be sure it is
+	 * really interrupting.
+	 * Then assign "struct device *dev"
+	 */
+	struct net_device *dev = (struct net_device *)dev_id;
+	/* ... and check with hw if it's really ours */
+
+	/* paranoid */
+	if (!dev)
+		return;
+
+	/* Lock the device */
+	priv = netdev_priv(dev);
+	spin_lock(&priv->lock);
+
+	/* retrieve statusword: real netdevices use I/O instructions */
+	statusword = priv->status;
+	priv->status = 0;
+	if (statusword & SNULL_RX_INTR) {
+		/* send it to snull_rx for handling */
+		pkt = priv->rx_queue;
+		if (pkt) {
+			priv->rx_queue = pkt->next;
+			snull_rx(dev, pkt);
+		}
+	}
+	if (statusword & SNULL_TX_INTR) {
+		/* a transmission is over: free the skb */
+		priv->stats.tx_packets++;
+		priv->stats.tx_bytes += priv->tx_packetlen;
+		dev_kfree_skb(priv->skb);
+	}
+
+	/* Unlock the device and we are done */
+	spin_unlock(&priv->lock);
+	if (pkt) snull_release_buffer(pkt); /* Do this outside the lock! */
+	return;
+}
+
+/*
+ * A NAPI interrupt handler.
+ */
+static void snull_napi_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+	int statusword;
+	struct snull_priv *priv;
+
+	/*
+	 * As usual, check the "device" pointer for shared handlers.
+	 * Then assign "struct device *dev"
+	 */
+	struct net_device *dev = (struct net_device *)dev_id;
+	/* ... and check with hw if it's really ours */
+
+	/* paranoid */
+	if (!dev)
+		return;
+
+	/* Lock the device */
+	priv = netdev_priv(dev);
+	spin_lock(&priv->lock);
+
+	/* retrieve statusword: real netdevices use I/O instructions */
+	statusword = priv->status;
+	priv->status = 0;
+	if (statusword & SNULL_RX_INTR) {
+		snull_rx_ints(dev, 0);  /* Disable further interrupts */
+		netif_rx_schedule(dev);
+	}
+	if (statusword & SNULL_TX_INTR) {
+        	/* a transmission is over: free the skb */
+		priv->stats.tx_packets++;
+		priv->stats.tx_bytes += priv->tx_packetlen;
+		dev_kfree_skb(priv->skb);
+	}
+
+	/* Unlock the device and we are done */
+	spin_unlock(&priv->lock);
+	return;
+}
+
+
+
+/*
+ * Transmit a packet (low level interface)
+ */
+static void snull_hw_tx(char *buf, int len, struct net_device *dev)
+{
+	/*
+	 * This function deals with hw details. This interface loops
+	 * back the packet to the other snull interface (if any).
+	 * In other words, this function implements the snull behaviour,
+	 * while all other procedures are rather device-independent
+	 */
+	struct iphdr *ih;
+	struct net_device *dest;
+	struct snull_priv *priv;
+	u32 *saddr, *daddr;
+	struct snull_packet *tx_buffer;
+    
+	/* I am paranoid. Ain't I? */
+	if (len < sizeof(struct ethhdr) + sizeof(struct iphdr)) {
+		printk("snull: Hmm... packet too short (%i octets)\n",
+				len);
+		return;
+	}
+
+	if (0) { /* enable this conditional to look at the data */
+		int i;
+		PDEBUG("len is %i\n" KERN_DEBUG "data:",len);
+		for (i=14 ; i<len; i++)
+			printk(" %02x",buf[i]&0xff);
+		printk("\n");
+	}
+	/*
+	 * Ethhdr is 14 bytes, but the kernel arranges for iphdr
+	 * to be aligned (i.e., ethhdr is unaligned)
+	 */
+	ih = (struct iphdr *)(buf+sizeof(struct ethhdr));
+	saddr = &ih->saddr;
+	daddr = &ih->daddr;
+
+	((u8 *)saddr)[2] ^= 1; /* change the third octet (class C) */
+	((u8 *)daddr)[2] ^= 1;
+
+	ih->check = 0;         /* and rebuild the checksum (ip needs it) */
+	ih->check = ip_fast_csum((unsigned char *)ih,ih->ihl);
+
+	if (dev == snull_devs[0])
+		PDEBUGG("%08x:%05i --> %08x:%05i\n",
+				ntohl(ih->saddr),ntohs(((struct tcphdr *)(ih+1))->source),
+				ntohl(ih->daddr),ntohs(((struct tcphdr *)(ih+1))->dest));
+	else
+		PDEBUGG("%08x:%05i <-- %08x:%05i\n",
+				ntohl(ih->daddr),ntohs(((struct tcphdr *)(ih+1))->dest),
+				ntohl(ih->saddr),ntohs(((struct tcphdr *)(ih+1))->source));
+
+	/*
+	 * Ok, now the packet is ready for transmission: first simulate a
+	 * receive interrupt on the twin device, then  a
+	 * transmission-done on the transmitting device
+	 */
+	dest = snull_devs[dev == snull_devs[0] ? 1 : 0];
+	priv = netdev_priv(dest);
+	tx_buffer = snull_get_tx_buffer(dev);
+	tx_buffer->datalen = len;
+	memcpy(tx_buffer->data, buf, len);
+	snull_enqueue_buf(dest, tx_buffer);
+	if (priv->rx_int_enabled) {
+		priv->status |= SNULL_RX_INTR;
+		snull_interrupt(0, dest, NULL);
+	}
+
+	priv = netdev_priv(dev);
+	priv->tx_packetlen = len;
+	priv->tx_packetdata = buf;
+	priv->status |= SNULL_TX_INTR;
+	if (lockup && ((priv->stats.tx_packets + 1) % lockup) == 0) {
+        	/* Simulate a dropped transmit interrupt */
+		netif_stop_queue(dev);
+		PDEBUG("Simulate lockup at %ld, txp %ld\n", jiffies,
+				(unsigned long) priv->stats.tx_packets);
+	}
+	else
+		snull_interrupt(0, dev, NULL);
+}
+
+/*
+ * Transmit a packet (called by the kernel)
+ */
+int snull_tx(struct sk_buff *skb, struct net_device *dev)
+{
+	int len;
+	char *data, shortpkt[ETH_ZLEN];
+	struct snull_priv *priv = netdev_priv(dev);
+	
+	data = skb->data;
+	len = skb->len;
+	if (len < ETH_ZLEN) {
+		memset(shortpkt, 0, ETH_ZLEN);
+		memcpy(shortpkt, skb->data, skb->len);
+		len = ETH_ZLEN;
+		data = shortpkt;
+	}
+	dev->trans_start = jiffies; /* save the timestamp */
+
+	/* Remember the skb, so we can free it at interrupt time */
+	priv->skb = skb;
+
+	/* actual deliver of data is device-specific, and not shown here */
+	snull_hw_tx(data, len, dev);
+
+	return 0; /* Our simple device can not fail */
+}
+
+/*
+ * Deal with a transmit timeout.
+ */
+void snull_tx_timeout (struct net_device *dev)
+{
+	struct snull_priv *priv = netdev_priv(dev);
+
+	PDEBUG("Transmit timeout at %ld, latency %ld\n", jiffies,
+			jiffies - dev->trans_start);
+        /* Simulate a transmission interrupt to get things moving */
+	priv->status = SNULL_TX_INTR;
+	snull_interrupt(0, dev, NULL);
+	priv->stats.tx_errors++;
+	netif_wake_queue(dev);
+	return;
+}
+
+
+
+/*
+ * Ioctl commands 
+ */
+int snull_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
+{
+	PDEBUG("ioctl\n");
+	return 0;
+}
+
+/*
+ * Return statistics to the caller
+ */
+struct net_device_stats *snull_stats(struct net_device *dev)
+{
+	struct snull_priv *priv = netdev_priv(dev);
+	return &priv->stats;
+}
+
+/*
+ * This function is called to fill up an eth header, since arp is not
+ * available on the interface
+ */
+int snull_rebuild_header(struct sk_buff *skb)
+{
+	struct ethhdr *eth = (struct ethhdr *) skb->data;
+	struct net_device *dev = skb->dev;
+    
+	memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
+	memcpy(eth->h_dest, dev->dev_addr, dev->addr_len);
+	eth->h_dest[ETH_ALEN-1]   ^= 0x01;   /* dest is us xor 1 */
+	return 0;
+}
+
+
+int snull_header(struct sk_buff *skb, struct net_device *dev,
+                unsigned short type, void *daddr, void *saddr,
+                unsigned int len)
+{
+	struct ethhdr *eth = (struct ethhdr *)skb_push(skb,ETH_HLEN);
+
+	eth->h_proto = htons(type);
+	memcpy(eth->h_source, saddr ? saddr : dev->dev_addr, dev->addr_len);
+	memcpy(eth->h_dest,   daddr ? daddr : dev->dev_addr, dev->addr_len);
+	eth->h_dest[ETH_ALEN-1]   ^= 0x01;   /* dest is us xor 1 */
+	return (dev->hard_header_len);
+}
+
+
+
+
+
+/*
+ * The "change_mtu" method is usually not needed.
+ * If you need it, it must be like this.
+ */
+int snull_change_mtu(struct net_device *dev, int new_mtu)
+{
+	unsigned long flags;
+	struct snull_priv *priv = netdev_priv(dev);
+	spinlock_t *lock = &priv->lock;
+    
+	/* check ranges */
+	if ((new_mtu < 68) || (new_mtu > 1500))
+		return -EINVAL;
+	/*
+	 * Do anything you need, and the accept the value
+	 */
+	spin_lock_irqsave(lock, flags);
+	dev->mtu = new_mtu;
+	spin_unlock_irqrestore(lock, flags);
+	return 0; /* success */
+}
+
+/*
+ * The init function (sometimes called probe).
+ * It is invoked by register_netdev()
+ */
+void snull_init(struct net_device *dev)
+{
+	struct snull_priv *priv;
+#if 0
+    	/*
+	 * Make the usual checks: check_region(), probe irq, ...  -ENODEV
+	 * should be returned if no device found.  No resource should be
+	 * grabbed: this is done on open(). 
+	 */
+#endif
+
+    	/* 
+	 * Then, assign other fields in dev, using ether_setup() and some
+	 * hand assignments
+	 */
+	ether_setup(dev); /* assign some of the fields */
+
+	dev->open            = snull_open;
+	dev->stop            = snull_release;
+	dev->set_config      = snull_config;
+	dev->hard_start_xmit = snull_tx;
+	dev->do_ioctl        = snull_ioctl;
+	dev->get_stats       = snull_stats;
+	dev->change_mtu      = snull_change_mtu;  
+	dev->rebuild_header  = snull_rebuild_header;
+	dev->hard_header     = snull_header;
+	dev->tx_timeout      = snull_tx_timeout;
+	dev->watchdog_timeo = timeout;
+	if (use_napi) {
+		dev->poll        = snull_poll;
+		dev->weight      = 2;
+	}
+	/* keep the default flags, just add NOARP */
+	dev->flags           |= IFF_NOARP;
+	dev->features        |= NETIF_F_NO_CSUM;
+	dev->hard_header_cache = NULL;      /* Disable caching */
+
+	/*
+	 * Then, initialize the priv field. This encloses the statistics
+	 * and a few private fields.
+	 */
+	priv = netdev_priv(dev);
+	memset(priv, 0, sizeof(struct snull_priv));
+	spin_lock_init(&priv->lock);
+	snull_rx_ints(dev, 1);		/* enable receive interrupts */
+	snull_setup_pool(dev);
+}
+
+/*
+ * The devices
+ */
+
+struct net_device *snull_devs[2];
+
+
+
+/*
+ * Finally, the module stuff
+ */
+
+void snull_cleanup(void)
+{
+	int i;
+    
+	for (i = 0; i < 2;  i++) {
+		if (snull_devs[i]) {
+			unregister_netdev(snull_devs[i]);
+			snull_teardown_pool(snull_devs[i]);
+			free_netdev(snull_devs[i]);
+		}
+	}
+	return;
+}
+
+
+
+
+int snull_init_module(void)
+{
+	int result, i, ret = -ENOMEM;
+
+	snull_interrupt = use_napi ? snull_napi_interrupt : snull_regular_interrupt;
+
+	/* Allocate the devices */
+	snull_devs[0] = alloc_netdev(sizeof(struct snull_priv), "sn%d",
+			snull_init);
+	snull_devs[1] = alloc_netdev(sizeof(struct snull_priv), "sn%d",
+			snull_init);
+	if (snull_devs[0] == NULL || snull_devs[1] == NULL)
+		goto out;
+
+	ret = -ENODEV;
+	for (i = 0; i < 2;  i++)
+		if ((result = register_netdev(snull_devs[i])))
+			printk("snull: error %i registering device \"%s\"\n",
+					result, snull_devs[i]->name);
+		else
+			ret = 0;
+   out:
+	if (ret) 
+		snull_cleanup();
+	return ret;
+}
+
+
+module_init(snull_init_module);
+module_exit(snull_cleanup);
diff --git a/snull/snull.h b/snull/snull.h
new file mode 100644
index 0000000..69a49a0
--- /dev/null
+++ b/snull/snull.h
@@ -0,0 +1,49 @@
+
+/*
+ * snull.h -- definitions for the network module
+ *
+ * Copyright (C) 2001 Alessandro Rubini and Jonathan Corbet
+ * Copyright (C) 2001 O'Reilly & Associates
+ *
+ * The source code in this file can be freely used, adapted,
+ * and redistributed in source or binary form, so long as an
+ * acknowledgment appears in derived source files.  The citation
+ * should list that the code comes from the book "Linux Device
+ * Drivers" by Alessandro Rubini and Jonathan Corbet, published
+ * by O'Reilly & Associates.   No warranty is attached;
+ * we cannot take responsibility for errors or fitness for use.
+ */
+
+/*
+ * Macros to help debugging
+ */
+
+#undef PDEBUG             /* undef it, just in case */
+#ifdef SNULL_DEBUG
+#  ifdef __KERNEL__
+     /* This one if debugging is on, and kernel space */
+#    define PDEBUG(fmt, args...) printk( KERN_DEBUG "snull: " fmt, ## args)
+#  else
+     /* This one for user space */
+#    define PDEBUG(fmt, args...) fprintf(stderr, fmt, ## args)
+#  endif
+#else
+#  define PDEBUG(fmt, args...) /* not debugging: nothing */
+#endif
+
+#undef PDEBUGG
+#define PDEBUGG(fmt, args...) /* nothing: it's a placeholder */
+
+
+/* These are the flags in the statusword */
+#define SNULL_RX_INTR 0x0001
+#define SNULL_TX_INTR 0x0002
+
+/* Default timeout period */
+#define SNULL_TIMEOUT 5   /* In jiffies */
+
+extern struct net_device *snull_devs[];
+
+
+
+
diff --git a/snull/snull_load b/snull/snull_load
new file mode 100644
index 0000000..47de578
--- /dev/null
+++ b/snull/snull_load
@@ -0,0 +1,8 @@
+#!/bin/sh
+
+export PATH=/sbin:/bin
+
+# Use a pathname, as new modutils don't look in the current dir by default
+insmod ./snull.ko $*
+ifconfig sn0 local0
+ifconfig sn1 local1
diff --git a/snull/snull_unload b/snull/snull_unload
new file mode 100644
index 0000000..a857ac9
--- /dev/null
+++ b/snull/snull_unload
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+/sbin/ifconfig sn0 down
+/sbin/ifconfig sn1 down
+/sbin/rmmod snull