I want to learn how printing works in UEFI but can't find any reliable resource that details the function. I don't want to copy from the library as that won't tell me much of how it actually works.
Can anyone please explain how printing in UEFI works?
Thank you
well, this is impossible, because the printing behavior does not print anywhere really, you can see it on UEFI Shell which is an UEFI App by itself.
If you want to implement low level printing, you can read about using serial ports, this is the easiest one.
I'd like to communicate with mpv using Unix sockets, but Perl 6 doesn't offer any high level interface for doing that. So I thought I could write a little module for that, started digging deeper, found the implementation of IO::Socket::INET, and learned about the NQP ops nqp::socket and nqp::connect.
However, I couldn't find any mention of those in the NQP operations list, and they seem to be quite distinct from the traditional BSD socket API. Hence I'd like to ask: are those two able to create a Unix socket and connect to it? If so, how? Or is there perhaps another way?
I think the best way right now is to use the NativeCall interface to call the C level functions. There are some old design documentation that suggest an IO::Socket::UNIX was thought about. But it's not made it into contemporary releases of the language specification (yet).
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I want to learn linux kernel device driver programming. So can anyone please post good tutorials pages or links here. I am new to linux kernel environment. I have searched for it but I don't know how to start and which one to read for easy understanding basics. Thanks in advance.
Depends on your current skills. If you're really new to Linux, perhaps you should start with user space system programming with Advanced Linux Programming. You'll get good knowledge of Unix system calls and other concepts such as signals, processes/threads and so on with this free resource. This is a must (understanding the user space API) if you're developing on the kernel side since the role of a kernel is providing services to users in a secure way.
Otherwise one often cited book is Linux Device Drivers, Third Edition (LDD3). Keep in mind that this edition was written at the time of Linux 2.6.10 and some things changed since then. This article shows the differences as 2.6 evolved (until 2.6.31, that is, so not very useful). I should mention martinezjavier/ldd3, which contains example drivers of LDD3 updated for more recent kernels (thanks to 42n4 for pointing that out).
Another interesting book that's not as often cited is Essential Linux Device Drivers. You won't find a free version of this one, but it still features an interesting approach. What I like about this one is it covers lots of different device types and is up-to-date as of 2.6.24, which is a bit better than LDD.
Finally, one great book about the kernel itself (not specifically for drivers) is Understanding the Linux Kernel, 3rd Edition. This covers in-depth kernel facilities and internal mechanisms. It's up-to-date as of 2.6.11.
As for online tutorials, I found this post on Pete's Blog is a really great example. Not only does it show how to create a character device (the most easy kernel driver type, i.e. the one you should start with), it uses modern Linux kernel features in an easy to understand fashion, including:
use of udev
use of a kernel data structure (FIFO)
use of kernel synchronization (mutex)
use of Sysfs with custom attributes
module options for insmod
Plus: it's aimed at Linux 3.0, which means it's more up-to-date compared to other resources.
You might also like this post about how to create Sysfs entries manually, although the Linux device model will take care of registering your device as a Sysfs entry if you don't need additional nodes or attributes.
Edit: I should add that the best way to learn real Linux device driver programming is to look at actual drivers. There are thousands of drivers in drivers. Start reading and understanding the concept of simple ones like drivers/leds and you will see how rewarding this is.
The site with very important links:
http://elinux.org/Device_drivers
Great tutorial with real examples (ends with an usbpen formatted with our own file system - search for author further articles):
http://www.linuxforu.com/tag/linux-device-drivers-series/
http://sysplay.in/index.php?pagefile=lfy_articles
Source code of famous LDD3 book ported to newest kernels:
https://github.com/martinezjavier/ldd3/
Videos:
https://www.youtube.com/playlist?list=PL16941B715F5507C5
Maybe other cources:
http://www.skilledup.com/courses?keyword=linux+kernel&price_filter=0..0
Some examples:
http://www.staerk.de/thorsten/index.php/My_Tutorials/Writing_Linux_kernel_modules
http://www.freesoftwaremagazine.com/articles/drivers_linux
http://techblog.aasisvinayak.com/kernel-module-programming-tutorial/
http://www.linuxforu.com/2009/05/a-voyage-to-the-kernel-day-11/
Books (without mentioned in this thread LDD3):
http://www.coopj.com/ with an updated source code http://www.coopj.com/LPD/
KernelHacking:
http://kernelnewbies.org/KernelHacking
Visual map of the linux kernel: http://www.makelinux.net/kernel_map/
Linux and kernel books for beginners:
http://www.kroah.com/lkn/
http://swift.siphos.be/linux_sea/
You might be interested in the newly released Linux Driver Templates. As the name suggests, it provides templates and demonstrates frequently used Linux facilities to get started quickly.
I understand it is a delayed response !!
You can pick any book, those are really great books suggested above.
But you need to really work practically. Try to be involved into Kernel as much as possible.
Mostly you need to look into kernel source code itself.
And the most interesting document you can find in Documentation folder under Kernel tree.
best book for learning device driver programming is
"LDD"
Professional Linux Kernel Architecture is a good read also.
The best source is the linux man pages but they are somewhat critical to understand for a beginner, Directly programming device drivers is not a easy task. I recommend you to go through pointers and structures through following books
Basic C Books 1. Programming C - Byron gottfried 2. The C Programming Language - Dennis Ritchie
Intermediate Books 1. Pointers on C Kenneth Reek 2. Expert C Programming Deep Secrets - Linden
Coming to device Drivers I have uploaded the Kernel Source documentation in pdf format https://drive.google.com/folderview?id=0B7iRyndFhHldR3hjOHpOZTdKTjA&usp=sharing Youcan download from this link.
Device Drivers Basics (User mode Programming)
Linux Programming interface - Michael Kerrisk
Beginning Linux Programming Wrox Publishers
Device Drivers (Kernel Deleopment) 1. Linux Kernel Development - Robert Love 2. Linux Kernel Internals - m beck
Device Drivers (Driver Programming) 1. Linux Device Drivers - Third Edition (Free Download is available for 2.6 Kernel) 2. Essential Linux Device Drivers - Venkateswaran
For Basic Driver Knowledge Follow this site http://www.tldp.org/LDP/khg/HyperNews/get/devices/devices.html
My Experience is First of all we must gain a sound knowledge on C Programming, mainly Structures and Pointers before going through Driver Programming otherwise it will be bit cumbersome to understand driver programming.
Comming to Startup :-
User space programming
Basics of gcc generating proprocessed, assembler and object files using gcc commands analysis of object files using different object tools, Basic programming in linux, threads(locks, synchronization techniques), signals, processes(fork, exec), timers(Posix). This will help you lot in understanding kernel concepts.
Kernel Programming
Understanding the kernel source tree, different branches and their importance, using ctags and cscope to browse kernel source code, this will help you in kernel source browsing.
Driver Programming
First of all Learn different driver classes, char, block etc.,
Next learn the device protocols, transmission and reception, the product manual is the best source for going through this.
Then start writing the simple char driver for example RTC (a port mapped device), IOAPIC (A memory mapped device), then go to USB, PCI, Network, I2C, SPI etc., if you want the help you can find the skeleton code for all this in kernel source tree.
I have least knowledge on network domain.Please bare with my question if it is basic
I would like to know how to communicate between two applications using TCP/ip protocol in
windows XP say for example
Using Perl and TK I am building a GUI with entry widget and i have an other external application which is installed in the system say APPLICATION.exe
Now i need to establish the connection using TCP between my perl program and external application APPLICATION.exe
for testing purpose what ever I type in the GUI Entry this external application has to receive (hope it receives as bytes)and external application will send some data and i need to process that data in my perl program..
I am totally unaware whether this is simple task or complicated.
If there are any modules existing in perl for similar programming please suggest me.
I highly appreciate if anyone can provide me the answer with an example.
Thanks to all
It is simple if you have done network programming before. If not, it is intermediately difficult because you need to get a grip on the underlying concepts and terminology first - read a book about the topic if necessary.
I recommend to use IO::Socket::IP. If you have Perl 5.14 or later, you can also use IO::Socket::INET that is distributed with Perl. See https://stackoverflow.com/a/8582550/46395 for a code example and links to further documentation.
I have looked online at making a multi-threaded server in perl, but i cannot find any good ones that clearly explain how to create one. I have created a server and client in perl but i do not seem to be able to make it multi-threaded. Can someone help me?
Assuming you are using the Net::Server CPAN module (rather than rolling your own), you could make use of Net::Server::Coro to build a multi-threded server. Note that Net::Server can handle (pre)forking (i.e. multi-processes) servers and these may be easer to use.
I think POE might be what you're looking for.
See the POE Cookbook for examples.