I have an (old) embedded system for which I want to compile programs. I don't have the toolchain, so I want to create one.
The embedded system has an "ARM926EJ-S rev 5 (v5l)" CPU and "cat /proc/version" says that it runs "Linux version 2.6.20.7" with GCC 4.0.2.
I have heard that I have to include the kernel headers in the build process. I download the Linux kernel version 2.6.20 from kernel.org, extract all files and run "make headers_install ARCH=arm INSTALL_HDR_PATH=~/headers". Is this the correct way or do I need the header files of the specific kernel?
untar the kernel.
make mrproper
make ARCH=${arch} headers_check
e.g make ARCH=arm headers_check
make ARCH=${CLFS_ARCH} INSTALL_HDR_PATH=dest headers_install
This are the steps to get headers from kernel.
The purpose of kernel headers is -->C library and compiled programs needs to interact with the kernel
i.e for Available system calls and their numbers, Constant definitions, Data structures, etc.
Therefore, compiling the C library requires kernel headers, and many applications also require them.
do I need the header files of the specific kernel?
The kernel-to-userspace ABI is backward compatible
--> 1)Binaries generated with a toolchain using kernel headers older
than the running kernel will work without problem, but won't
be able to use the new system calls, data structures, etc.
-->2)Binaries generated with a toolchain using kernel headers newer
than the running kernel might work on if they don't use the
recent features, otherwise they will break.
--->3)Using the latest kernel headers is not necessary, unless access
to the new kernel features is needed
So in your case kernel version is "Linux version 2.6.20.7"
You can use kernel headers of Linux kernel version 2.6.20 or 2.6.21 from kernel.org.
does not create any problem in this case.
That should be fine if you're using the headers to build a libc
You should probably run make ARCH=arm headers_check beforehand too.
Related
So I've been gifted 2x gen 1 Galileos that I want to try to do something with before I throw them in the garbage.
It's my understanding that they wont run most i386 kernels from most distros as they need to be Pentium II compile flags.
So this guy shared his kernel configs https://twitter.com/kerneldave/status/1359178557570732032 and I have compiled the kernels using a standard GCC stack on ubuntu.
I cannot get the resulting kernel to boot. After Grub loads the kernel there is no activity on the console (via the serial cable)
Will mainline kernels work on Gen 1?
Does it need to be compiled with some special toolchain or will gcc be fine?
Any special boot params need to be used, APIC/ACPI, console options?
Thanks
I use CentOS and it does not have support for L2TPv3 which was introduced in 2.6.35.
CentOS is at 2.6.32. How do I selectively patch just the L2TPv3 changes to my kernel?
Also, these are kernel modules. Would I need to run the modified kernel to be able to insmod these KOs?
Back porting features is a very non trivial task, not something that can easily be done casually. Thus, your best option is to look around whether somebody created the necessary patches for your kernel version.
Also, Linux kernel has no strict interface definitions when modules are concerned, thus it is very desirable that kernel and modules are compiled from the same source. Sometimes it is possible to successfully use "mismatched" modules with a given kernel, but rather frequently an attempt to do so results in various problems.
But if you will adventurous, try using modprobe -f. This will disable the module version checking and modprobe will try to squeeze the module in (even at a cost of crashing the system on spot).
I am trying to port my own driver to a Beagle board xm arm-cortex-A8. While porting I am trying to figuring out how the .ko file actually builds. In our Makefile we only have a command to build an.o file.
How is a .ko file built?
Using linux-2.6.38.8 kernel and trying to configure my driver for my kernel.
The kernel kbuild module document has lots of information on how to build an external module. If you have Raspberian or some other embedded ARM Linux, you will need to get the source package for your kernel. The process differs based on whether you are compiling on the same machine the module will run on, or if you are trying to build it on a PC (hopefully a Linux PC).
Please specify which way you need to build, if the kbuild module document doesn't explain things well enough.
Is it possible for gcc, installed on fedora 16, to cross compile for a different CPU, say SPARC?
I have build a certain understanding, need some expert to correct me if I am wrong. Different operating systems differ by the system calls they use to access the kernel or entirely by the kernel they use. IS THIS CORRECT? different kernels understands different systems calls for accessing underlying hardware. binaries or executables or programs are nothing but a bunch of system calls only. therefore every OS has its own executable. an executable meant to run to on windows wound not run on linux. by cross compiling the source code of any windown's executable we can generate executable for other OSs. word PLATFORM means operating system. POSIX are certain design standards for UNIX-like OSs.
we usually cross compile for different OSs. BUT can we cross compile for different hardware too? for example, in case of a microcontroller which does not have an OS?
No. You can't use native machine (x86) gcc for compiling program files for a different architecture. For that you require a cross-compiler-gcc that is specific to that processor architecture.
Your understanding about system calls for OS is correct. Each OS has its own set of system call which is been used by library. These libraries at the end will be translated into machine language for the processor.
Each Processor Architecture has its own set of instruction know as Instruction Set Architecture(ISA). So when a program written in high-level-language (like C) is compiled, it should be converted into machine language from its ISA. This job is done by the compiler(gcc). A compiler will be specific to only one processor architecture. For example gcc is for x86 processor. So if you want a compiler for different processor in you x86 machine you should go for a cross-compiler of that processor.
You would have to build such a version. That's part of the process of porting gcc to a new platform. You build a version that cross-compiles, then you cross-compile that version, then you test that version on the new platform, debug, rinse, and repeat.
what is cross compilation?
Cross-compilation is the act of compiling code for one computer system (often known as the target) on a different system, called the host.
It's a very useful technique, for instance when the target system is too small to host the compiler and all relevant files.
Common examples include many embedded systems, but also typical game consoles.
A cross-compiler is compiles the source code from one architecture to another architecture.
For example: hello.c
gcc hello.c (gcc is a compiler for x86 architecture.)
arm-cortexa8-linux-gnueabihf-gcc hello.c
(arm-....-gcc is a compiler for the arm architecture.) This you are compiling on the host pc for a target board (e.g rpi, beaglebone, wega board). In this example arm-cortexa8-linux-gnueabihf-gcc is called the 'cross compiler'.
This process is called cross compilation.
see the link for more info cross compilation
To "cross compile" is to compile source on say a Linux box with intent on running it on a MAC or Windows box. This is usually done using a cross compilation plugin, which are readily available from various web servers across the net. If one is to install a cross compilation plugin onto their Linux box that is designed to compile for Windows boxes. Then they may compile for either a Linux/*NIX box as well as have the option to compile and link a Windows-ready executable. This is extremely convenient for a freelance programmer whom has access to no more than a single Linux/Windows/MAC box. Note that various cross compilation plugins will allow for multitudes of applications, some of which you may or may not perceive as useful, thus a thorough perusal of the plugin's README file.
Did you have a particular project in mind that you would like to apply the method of cross compilation to?
In a strict sense, it is the compilation of code on one host that is intended to run on another.
Most commonly it is used with reference to compilation for architectures that are not binary-compatible with the host -- for instance, building RISC binaries on a CISC CPU platform, or 64-bit binaries on a 32-bit system. Or, for example, building firmware intended to run on embedded devices (perhaps using the ARM CPU architecture) on Intel PC-based OSs.
A Cross Compiler is a compiler capable of creating executable code for a platform other than the one on which the compiler is running.
For e.g. a compiler that runs on a Windows 7 PC but generates code that runs on Android smartphone is a cross compiler.
A cross compiler is necessary to compile for multiple platforms from one machine.
A platform could be infeasible for a compiler to run on, such as for the microcontroller of an embedded system because those systems contain no operating system.
In paravirtualization one machine runs many operating systems, and a cross compiler could generate an executable for each of them from one main source.