I have been doing some bare metal programming in 32-bit iMX6q SABRE-SD board(arm Cortex-A9). I have used "arm-none-eabi" as the Toolchain. Now, I would like to port all the codes i have written to 64-bit arm Cortex-A57 (R-Car M3 board). How would i select the compiler for this task. Can i use the same compiler with some flag changes for compiling for 64-bit design. Or Will there be any specific compiler provided by the manufacturer.
How would someone select the compiler for his/her embedded design.
Please Help.
Regards,
Ajmal
For compiling into 64-bit architecture, linaro gcc tool could be used:
Please refer to this link:
https://community.arm.com/dev-platforms/f/discussions/5274/issue-compiling-armv8-assembly
Related
I'm using a MIPS cross compiler on my Linux machine which works great.
Now I need to compile the same application on Windows.
I'm searching the web for some prebuilt MIPS cross compiler (with toolchain) for MS-Windows, but without success.
Since I'm not sure how to do so, I'm asking if someone knows such prebuilt toolchain? or some guide how to convert my Linux toolchain for windows if it's possible?
Thanks.
You should use Codescape MIPS SDK.
It looks like Mentor has taken away the free MIPS toolchain from the CodeSourcery distribution. Maybe one of these might still work: https://www.linux-mips.org/wiki/Toolchains.
I am a beginner in programming and wanted to download a good C compiler to practice coding. So I thought of GCC and started a small research on it. I read a Wikipedia article on it. The article mentioned something about target architecture,which I do not know. Can anyone tell me what it means, and any source I can refer for more information. Thanks in advance.
The target architecture is the architecture which the compiler creates binary files for.
Common architectures are: i386 (Intel 32-bit), x86_64 (Intel 64-bit), armv7, arm64, etc...
GCC compiles C code (after the preprocessing stage) to assembly code,
and the assembly code varies depending on the CPU architecture.
The assembly code is then "assembled" to a binary file.
Something to keep in mind:
Two binary files are not guaranteed to be compatible across different operating systems despite sharing the same architecture.
A program compiled on Ubuntu Linux (let's say with arch x86_64) won't work on Windows (with same arc x86_64).
GCC identifies architectures by "triplets", like:
x86_64-apple-darwin14.0.0
i386-pc-mingw32
i686-pc-linux-gnu
Format is:
machine-vendor-operatingsystem (not always followed though)
They contain infos on both the architecture and the operating system.
Is there a guide somewhere that describes how to get LLVM to emit a binary for Cortex-M3 that I can massage into running bare metal? I've spent considerable time playing with LLVM on Windows and Ubuntu to no avail. I can get ARM-like assembly out. I can get bit code out, but what I really need is ELF, DWARF, Hobbit, Gandalf or any other Lord of the Rings critter that has a file format specification. Any and all help appreciated! I'm compiling LLVM 3.4 with CLANG on Ubuntu, Windows and/or OS X.
I created a firmware framework - PolyMCU https://github.com/labapart/polymcu - that is based on CMake that support GCC and LLVM. Because it is based on CMake you can build your firmware on Linux/Windows/MacOS.
It also uses Newlib and supports Baremetal/CMSIS RTOS (RTX)/FreeRTOS.
The benefit of using PolyMCU is this framework does not add any software layer on top of the libc and the MCU vendor's SDKs.
Another benefit is you can easily switch toolchains. I used this feature to get more feedback on my code by testing it with many compilers.
I also wrote a blog where I compared GCC and LLVM build size on ARM Cortex-M: http://labapart.com/blogs/3-the-importance-of-the-toolchain-version-in-embedded-space Interesting results, Clang generated code is not much bigger than GCC on Cortex-M...
The best guide that I know of is here: http://wiki.osdev.org/LLVM_Cross-Compiler. It's mostly about building an LLVM cross-compiler, but it does show a "Usage" section. However, that section specifically shows an example for a Cortex-A processor, but you should be able to get the general idea.
I have created an simple clang bare metal Cortex-M3 "hello world" program, but I don't have it in front of me. IIRC, the only options I needed were -march=thumb -mcpu=cortex-m3 as long as the LLVM compiler backend was built with the ARM thumb backend support (Again, see http://wiki.osdev.org/LLVM_Cross-Compiler). I did, however, need to link with arm-none-eabi-ld from the GCC toolchain here (http://launchpad.net/gcc-arm-embedded), and I believe that is how you can get your ELF binary.
I've since moved on to the D programming language, and I have a simple example using LDC (The LLVM D compiler) here (http://wiki.dlang.org/Extremely_minimal_semihosted_%22Hello_World%22)
So, I believe compiling bare metal ARM Cortex-M3 software with LLVM can be done, but it seems not many people have tried.
It is possible to use clang++ pulled from http://llvm.org/builds with https://launchpad.net/gcc-arm-embedded as a base, at least for the compile step.
Required extra arguments are the include paths hardcoded into gcc and certain arm-none-eabi defaults:
--target=arm-none-eabi -fshort-enums -isystem "../arm-none-eabi/include/c++/5.2.1" [-isystem ...]
Hopefully this hasn't been asked and answered already, but I just had a quick question on ARM.
Specifically, if when compiling Android (which has a lot of C and C++), you use GCC to compile, doesn't that create x86 based code? How is it that an ARM processor, which uses a reduced instruction set, can interpret this code and run like it does?
Thanks!
GCC doesn't just compile for x86. It actually compiles to any instruction set. If you wanted to you could create a new one just by adding a few files.
And ARM isn't a reduced instruction set. Its a completely different instruction set. There's some things ARM has that x86 doesn't and vice versa.
Building gcc goes through a configuration step, part of this is to specify a back-end. The back-end is responsible for op-code generation. The typical compiler is many phases. Briefly,
Parser - convert text to a data representation.
Front end - Optimize by changing code constructs, possibly language specific.
Middle end - Performs computer science optimization that are common to any compiler.
Back end - Performs optimization specific to the target CPU.
See stackoverflow compiler wiki for more.
So parts one to three are common for the x86 and the ARM versions of gcc (or any gcc). The Android compiler is a version of gcc which has been configured to generate ARM code. It is a different compiler than the one that normally runs on an x86. You maybe running an ARM emulator on a PC and then believe that this code is run by the x86. However, this is a virtual ARM machine running this code. An x86 processor can not run ARM code natively.
The Android gcc is an ARM configured gcc. A normal Linux distributions gcc is configured for an x86 or x86_64.
Something is missing above: Who compiles the compiler? In both cases, an x86 compiler compile the new compiler. The difference is the selected back-end. One is x86, the other ARM. Both compilers run on an x86, but they generate code for different targets. Gcc can only generate code for an ARM or an x86; never both via any sort of command line switch. A compiler build usually refers to three different CPU types.
Build - Machine where the compiler is built. This is the compiler's compiler.
Host - the machine the compiler runs on. Not it's output, but the compiler itself.
Target - the machine the back-end targets. The one code is generated for.
I think maybe people are thinking because they both run on the same host, they must generate code for the same target. But that is not true; it is a little mind bending at first. Depending on the setup, you may need compilers for each of these machines to make a final compiler.
The first compiler for any machine is usually a cross compiler. Except for some people who made primitive compilers long ago in assembler.
See also: Cross compiler.
to put it simply, when you're building for ARM on your x86 computer you're using a cross-compiler - a compiler that runs on one platform but generates code for another. This is extremely common when developing for embedded or mobile platforms.
I have started working on STM32F4 Discovery board and have compiled and run a few basic programs using the latest Yagarto toolchain containing the GCC 4.6.2. Lately though on several forums I have read that many toolchains including the latest Yagarto have problems when it comes to using the on-board hardware FPU. I have also read that the latest CodeSourcery toolchain does support hardware floating point, but not in the lite edition!!
While digging deep into the topic I found this toolchain which is specifically for ARM Cortex M/R controllers, and claims to have no problems when it comes to hardware FPU.
https://launchpad.net/gcc-arm-embedded
I wanted to know from users' experience, if the hardware FPU problems really exist in Yagarto? I am interested in using Yagarto because I also work on ARM7 and yagarto supports that as well. So instead of having different toolchains for different architectures, it is convineant to have one for both ARM7 and Cortex M/R.
If the FPU problems do really exist, then could anyone suggest me a good tried and tested toolchain for both ARM7 and Cortex M/R?
P.S. : I use CodeSourcery's latest GNU Linux toolchain for the BeagleBoard (Cortex A-8), havn't yet faced any issues with it.
I just wrote an article about using ARM's free GCC toolchain (GNU Tools for ARM Embedded Processors) and STLINK on Linux/Ubuntu to write/program/debug code for an STM32F4 Discovery Board (the F4 is a Cortex M4) - that may help you, the compiler does have hardware floating point support and I'm using it in my examples...
http://www.wolinlabs.com/blog/linux.stm32.discovery.gcc.html