I am just learning linux kernel programming with the LINUX KERNEL DEVELOPMENT book(I am beginner linux kernel programming but not on linux programming). It is possible to test programs in a kernel machine with VMware viritual on Ubuntu without damage my system ?
Yes you can safely test kernel modules on a virtual machine!
I'll give you some links that may help:
watch this site
http://free-electrons.com/
in particular this book:
http://free-electrons.com/doc/books/ldd3.pdf
Also this guide:
http://www.tldp.org/HOWTO/Module-HOWTO/
An embedded distro is even better
An Ubuntu guest is fine, but I prefer to keep things minimal and use an embedded distro, as this will make things:
simpler and easier to understand and control
faster
In particular, I recommend using:
Buildroot, which is highly configurable, documented and maintained, also builds host QEMU so easy to patch it up (e.g. to add your own devices since out-of-tree devices are not possible yet ?)
QEMU emulator: small comprehensible source, ARM support, official Android emulator, kernel GDB support
Embedded distros can generate rootfs images smaller than 10MiB, and it becomes possible to understand the entire userland setup, which will make it easier to focus on the kernel.
I have made a setup to make everything as automated as possible: https://github.com/cirosantilli/linux-kernel-module-cheat
I've been using a VM for a long time for Linux kernel programming and I've never had any problem. Actually, if you manage to violate the protections of a VM then you will probably be hired by Oracle or VMWare :D
However, I recommend you to read this post: https://security.stackexchange.com/questions/23452/is-it-safe-to-use-virtual-machines-when-examining-malware
Related
I was using PIC micro controller for my projects. Now I would like to move to ARM based Controllers. I would like to start ARM using Linux (using C). But I have no idea how to start using Linux. Which compiler is best, what all things I need to study like a lot of confusions. Can you guys help me on that? My projects usually includes UART, IIC, LCD and such things. I am not using any RTOS. Can you guys help me?
Sorry for my bad English
Once you put a heavyweight OS like Linux on a device, the level of abstraction from the hardware it provides makes it largely irrelevant what the chip is. If you want to learn something about ARM specifically, using Linux is a way of avoiding exactly that!
Morover the jump from PIC to ARM + Linux is huge. Linux does not get out of bed for less that 4Mb or RAM and considerably more non-volatile storage - and that is a bare minimum. ARM chips cover a broad spectrum, with low-end parts not even capable of supporting Linux. To make Linux worthwhile you need an ARM part with MMU support, which excludes a large range of ARM7 and Cortex-M parts.
There are plenty of smaller operating systems for ARM that will allow you to perform efficient (and hard real-time) scheduling and IPC with a very small footprint. They range form simple scheduling kernels such as FreeRTOS to more complete operating systems with standard device support and networking such as eCOS. Even if you use a simple scheduler, there are plenty of libraries available to support networking, filesystems, USB etc.
The answer to your question about compiler is almost certainly GCC - thet is the compiler Linux is built with. You will need a cross-compiler to build the kernel itself, but if you do have an ARM platform with sufficient resource, once you have Linux running on it, your target can host a compiler natively.
If you truly want to use Linux on ARM against all my advice, then the lowest cost, least effort approach to doing so is perhaps to use a Raspberry Pi. It is an ARM11 based board that runs Linux out of the box, is increasingly widely supported, and can be overclocked to 900MHz
You can also try using the Beagle Bone development board. To start with it has few features like UART I2C and others also u can give a try developing the device driver modules for the hardware.
ARM Linux compilers and build toolchains are provided by many vendors. Below are your options which I know of:
1.ARM themselves in form of their product DS-5 ;
2.Codesourcery now acquired by Mentor graphics. See some instructions to obtain & install, codesourcery toolchain for ARM linux here
3.To first start programming using ARM (C , assembly ) I find this Windows-Cygwin version of ARM linux tool chain very helpfull. Here. These are prebuilt executables which work under Cygwin(A Posix shell layer) on Windows.
4.Another option would be to cross compile gcc/g++ toolchain on Linux for ARM target of your choice. Search and web will have information about how it is done. But this could be a slightly mroe involved and long-winding process.
enjoy ARM'ing.
First, you should question yourself if you really need to program assembly language, most modern compilers are hard to beat when it comes to generating optimized code.
Then if you decide you really need it, you can make life easier for your self by using inline assembler, and let the compiler write the glue code for you, as shown in this wikipedia article.
Then the compiler to use: For free compilers there are practically only two choices: either gcc or clang.
There is also a non free toolchain from arm which when i last tried, 5 years ago, produced about 30% faster code than gcc at the time. I have not used it since.
The latest version of this compiler can be found here
You can also write standalone assembler code in .s files, both gcc and clang can compile .s into .o in the same way you would compile a .c or .cpp file.
Compile
If you are using a STM32 based microcontroller you need to get CMSIS and GNU arm-non-eabi-gcc package installed. Then you need to write your own makefile to pass your c codes into arm gcc compiler.
Programming
For the programming step you need to install openocd and configure that for your specific programmer. You can find a full description on how to do that on my blog
http://bijan.binaee.com/index.php/2016/04/14/how-to-program-cortex-m-under-gnulinux-arch/ and in my GitHub repository.
IDE
I'm using vim with CTags but you can use gEdit with the Shortcut plugin if you need a simpler text editor.
Can anyone suggest some good references for writing a touchpad driver for linux. Where would I get hardware documentation from. I have read most of the linux device driver books and now I want to take it to the next level.
Are you sure there is no current support for your sentelic in linux kernel? Take a look at Documentation/input/sentelic.txt in Linux source code. If it does not give you direct answers, you'll be able to see how to implement something similar instead. Take a look at its sources, too.
Moreover, if you are not really, really familiar with Linux kernel programming yet, you can read Linux Device Drivers (freely available), Linux Kernel Mode Programming (available, too) and Linux Kernel Development. Some of those sources are somewhat dated, but will give you right ideas about development.
I'm into something about writing a "Mock GPU driver" for Linux based systems. What I mean is that, simply I want to write a driver (Behind X-server obviously) to answer X's API calls with some debugging messages.
In other words I want to fool Linux about having an actual GPU. So I can make a test-bed for GUI-accelerated packages in console based systems.
Right now, if I execute a GUI-accelerated package in Linux console based systems; it'll simply dies due to lack of a real GPU (or a GPU driver better I'd say).
So I want to know:
Is it even possible? (Writing a GPU driver to fool Linux about having an actual GPU)
What resources do you recommend before getting my hands dirty in code?
Is there any similar projects around the net?
PS: I'm an experienced ANSI-C programmer but I don't have any clue in real Kernel/Driver development under *nix (read some tutorials about USB driver development though), so any resources about these areas will be really appreciated as well. Thanks in advance.
What you are looking for is actually part of Xorg server suite, and it is called Xvfb (virtual framebuffer).
If you're not afraid of a bit complex bash, you can take a look at Gentoo's virtualx.eclass for an use example (we use it to run tests which require X11).
A good place to start is the Mesa project - it implements OpenGL in software. It has a way to trick the OS into thinking that it is the OpenGL driver.
Next term, I'll need to write a basic operating system for Motorola 68K processor as part of a course lab material.
Is there a Linux emulator of a basic hardware setup with that processor? So my partners and I can debug quicker on our computers instead of physically restarting the board and stuff.
Is it possible to apply test-driven development technique to OS development? Code will be mostly assembly and C. What will be the main difficulties with trying to test-drive this? Any advice on how to do it?
I would recommend developing an operating system for the classic Amiga computers, which had different versions of the 68000 processor. Since the Amiga computer is a complete computer and is extremely well documented, I thought this would be a good exercise.
There is an emulator for it called UAE (and Win-UAE) which is very exact and
can be configured with different kinds of processors (68000 - 68060) and other capabilities. Normally, you would also need to acquire ROMs for it, but since you are developing an operating system yourself, this is not necessary.
Tools you will need is either Cygwin (for developing under Windows) or a Linux computer. Then you will need cross compilers. This includes both a C compiler and an assembler. Here is a template for creating a simple ROM which changes screen color and flicks the power LED. It will create a file 'kick.rom' which UAE then searches for in the current directory.
Reference on the 68000 instruction set can be found at the links below. Be aware that different assembler programs may use slightly different syntax and instruction set.
If you need to demo the operating system on real hardware, there are modern Amiga clones sold on Ebay and other places. Search for "Minimig".
Update:
Nowadays AROS also runs on UAE as well as physical Amigas.
Refs:
[UAE]
[WinUAE]
[Cygwin]
[Cross Compilers]
[68000 reference]
I would suggest QEMU for m68k emulation.
(The system emulator you want in QEMU is "Coldfire" - that's what Freescale calls the successor to the m68k architecture).
You certainly can tdd this project. First off decouple all accesses to the hardware with simple routine calls, e.g. getch() and printf, then you can provide simple mocks that provide test input and check output. You can then write well over 90% of the project on a PC using gcc, msdev or xcode. Once you have got some confidence in the decoupling routines you will need very little access to the hardware, and only then to occasionally check that your mocks are acting as you expect.
Keep to C until you find a particular bottle neck, and only then resort to assembler.
There are a few new projects that use hardware simulated 68000 cpus, the C-One project, the Minimig (Mini Amiga) project and the Natami (Native Amiga) project - they are new 68k compatible Amiga systems.
C One, reconfigurable computer, Minimig, in development, prototypes done: FPGA Arcade and Natami.
The Easy68k http://www.easy68k.com simulator might help you.
The uClinux project started on a m68k board. They may have the tools you need...
I like programming challenges, and writing a kernel seems a programming challenge.
Unfortunately, kernels are particularly hard to test because they are basically the core of operating systems and so they can't be easily ran on top of an operating system.
However, I know about applications called Virtual Machines that can emulate computer hardware.
What is the easiest/best way to develop and test kernels(C+Assembly) using Virtual Machines?
While BOCHS seems to be better at letting you know when something goes horribly wrong with your pet OS... it is very slooooow! I use VirtualPC for general purpose testing and BOCHS when things get murky.
Also, you will more than likely be booting the OS every 2 minutes, so it helps to have some sort of automated way to build a boot image & fire off the Virtual PC.
I built a GRUB boot floppy image with all the necessary stuff to get it to boot the Kernel.Bin from the root. I use a batch file to copy this file to the virtual project directory, use FAT Image Generator to copy my kernel to the image. Then just launch the VirtualPC project. Vola!
Excerpt from my batch file:
COPY Images\Base.vfd Images\Boot.vfd /Y
fat_imgen.exe modify Images\Boot.vfd -f Source\Bin\KERNEL.BIN
COPY Images\Boot.vfd Emulators\VirtualPC\ /Y
START Emulators\VirtualPC\MyOS.vmc
One last suggestion: Set the VirtualPC process priority to low - trust me on this one!
I'd be happy to exchange some code!
Tools: DGJPP, NASM, GRUB.
Code: osdev.org, osdever.net
You might be interested in looking at HelenOS. Its a from scratch microkernel that has been ported to many architectures (boots just fine on bare metal) developed using simulators such as Simics and QEMU.
We use a static grub that is copied to the final ISO during the build process. Some things just have to be that way until the OS becomes self hosting. I highly recommend NOT implementing your own userspace C library unless you really do want to do everything from scratch .. you'll become self hosting much sooner :)
Though Simics is non-free, I highly recommend it (and its built in debugging/profiling tools) while making your kernel. Once you have some kind of kernel console and logger in place, QEMU does a very nice job.
It's straightforward. Set up a virtual machine, write your kernel, copy it to the virtual machine, boot the virtual machine.
You'll need to be more specific if you want more specific advice.
Probably just setting up a machine (x86, I guess), and then investigate exactly how it behaves during boot. There should be one or more files in the host machine's file system that act as the virtual machine's file system, and then you'd need to put some boot sector information there that causes your in-development kernel to boot.
That would of course mean that the build system on the host has a way to write the kernel to the virtual machine's file system, which might vary in difficulty.
Picking one at random, bochs seems to support editing the boot media from the outside using standard tools like dd etc.
The first question that you need to ask yourself is what hardware architecture are you targeting? I'll assume for the sake of this discussion that you are targeting the IA_32 architecture, which would probably be a wise choice as there is plenty of readily-available documentation on that processor.
If you're truly serious about this undertaking, then you will definitely want to run your debug/code/build/deploy cycle against an emulator or VM. Someone mentioned BOCHS, which is very popular. If emulation speed is your thing, there is also an emulator called Qemu that is faster than BOCHS.
I'd suggest that your development environment run under Linux or Windows, which again would probably be a wise choice due to the available documentation for those dev environments.
Make is your friend. Use it to automate the build/execute process. I'd advise you to pick your toolsets/compilers up front, and spend some time learning them well. It will save you in the long run.