Writing a new device driver

Malice fordearlinux at gmail.com
Mon Jun 25 15:42:24 EDT 2012


I'm planning to write a new device driver on linux kernel . The device i 
intend to write will be a device that'll pipe the data coming into it to 
another computer that'll be also having the same device . So in short 
the device'll be readable/writable and should communicate through 
network . I know it sounds like a socket but the idea would be to 
implement a interface in shell so that if you type

|     root at host$echo "Hi">>mydevice

will transfer the word hi to the system on the other side of network 
(and may be configure it to store on file). This is a leisure time 
project i intend to do and it sounds much like sockets and other already 
existing implementations . Well the questions regarding the design for 
device implementations are : 1)Should i use a block or a character 
device . The advantage i see for a block device is that if i am a 
initiating a complete file transfer through the device(which i in tend 
to support later) , then it would be fast .

2)How do i write the data on the network . I'm familiar with sockets and 
stuff , but using sockets from with in the kernel has performance 
issues(I read it somewhere, after all sockets was desined to be used in 
userspace) . Will using netfilter or other stuffs work ?Maybe crafting 
the packet directly would help :-)? Any innovations are welcome

3)How do i configure the driver , like how do i let it know that it 
should connect to a specific host >in user space programs we usually do 
this by config files , but to change the connection settings of a driver 
how do you manage it ? (sysfs ?? Frankly i never worked with sysfs or 
proc/ )

4)Now as the design specifies all the transfer of files is in kernel 
space . When i transfer huge chunks of data through kernel space , will 
it slow down the system ?. The design shouldnt overload the system , 
doing it in a pre-empitble kernel will help, but are there other 
charecterstics i should be aware of to make the design as efficient as 
possible (i'm doing it on the latest linux kernel) ?

5)And i dont want to leave a huge memory imprint so is there any way i 
can reduce it while tranferring of data , may be cacheing data on disk ?

6)I will have to design a user space programme to co ordinate the driver 
wont i ? I cannot let the driver alone do the whole task , tat wud be 

Comments Welcome

I've also posted the same question at stackoverflow too


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