I want to create am minimal Linux system. I have compiled the kernel myself, but I want to use Yocto to build my rootfs. How can I build the smallest possible rootfs to startup and system and open a shell without building the kernel? Also, how can I choose the type of rootfs? I'd like it to be initramfs so I can then embed it in my kernel image.
Without more details both questions would require very long answers. Luckily the Development Manual covers the issues: See Building a tiny system and Building an initramfs image. I would suggest starting with those and asking more specific questions if needed.
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I have a project that could be built with the Yocto build system to generate a full disk image. According to the existing procedure, I can get only a full disk image that should be flashed on SD card.
And this does not suit my needs because I can't flash the image on the board. In my case, I need to build a certain project (that currently has a recipe) to an executable. (This project currently is a part of the full disk that is built with Yocto)
So I am wondering, is it possible to extract this executable (and the libraries that this executable depends on) from Yocto build files, so that I could copy and install it on the board? Which possibilities do I have to do this? Do I have some quick and dirty way to do this?
P.S: I heard something about that Yocto can provide a package for a certain project, that could be installed by the corresponding package manager on the board. On the board installed dpkg package manager.
It's a solution to add tar.gz to your IMAGE_FSTYPE.
After building the image, you can extract the executable you were looking for from the created archive.
Or you add the output format you need for your target and install the full image.
I have a custom board with imx6dl chip and peripherals. I have compiled u-boot, zImage and rootfs from examples provided by manufacturer. But when i try to build yocto from git repo with latests releases, it fails to run (some drivers not working, board is loading and display interface, but touchscreen is not working for ex.),
Is there any way to include precompiled binaries zImage, u-boot and device table to bitbake recipes? I'm very new to yocto project, and only need to get bootable image with working drivers and qt5.
If you have a working boot chain (e.g. u-boot, kernel and device tree) that you have built out-of-yocto, then you might try building a rootfs only. This requires two main settings, to be made in your local.conf to get started. Please don't firget that this is just a starting point, and it is highly advised to get the kernel/bootloader build sorted out really soon.
PREFERRED_PROVIDER_virtual/kernel = "linux-dummy to have no kernel being built, and something like MACHINE="qemuarm" to set up an armv7 build on poky later than version 3.0. The core-image-minimal target should at least be enough to drop you in a shell for starters, and then you can proceed from there.
Additionally, it might be qorth asking the board vendor or the yocto community (#yocto on the freenode server) if they know about a proper BSP layer. FSL things are quite nicely supported these days, and if your board is closely related to one of the well-known ones, you've got a high chance that meta-freescale just does the trick nicely.
Addition:
#Martin pointed out the mention of Qemu is misleading. This is just the easiest way to make Yocto build a userland for the armv7-architecture which the imx6dl is based on. The resulting root filesystem should be sufficiently compatible to get started, before moving on to more tuned MACHINE configuration.
I'm using Yocto project to build a linux kernel image following these steps:
https://www.at91.com/linux4sam/bin/view/Linux4SAM/Sama5d27Som1EKMainPage
For some reasons I just want to reduce my Image size so I can flash it on QSPI 8 Mega octet memory. I have tried to reduce the size of my rootFS, I have removed some packages that I found in .manifest file and some Distro features. But I did not find how can I modify the kernel size which size is fixed ( 4.2 Mega octet ).
I think that when I can remove some drivers that I don't need the kernel size will be reduced.
I just want to know how can I find what drivers are built in my image and where can I find them ? and later how can I delete the ones that I don't need ?
Thank you.
if you check the .config file that was generated for your BSP, it will show what drivers (and other things) were built into your kernel (check for the 'y' on all the options).
Such file should be somewhere in:
tmp/work//linux-yocto//linux-*-build/.config
Sorry that I can't give you the exact location, but it literally depends on what BSP/MACHINE you are building for.
Also, if you want to modify such configuration, you can call:
$ bitbake -c menuconfig virtual/kernel
that will bring up the menuconfig ncurses interface, in which you can not only see what is installed but also modify what you need.
I am building a yocto image for a multicore MCU (A7 + M4). The U-Boot and Linux run on A7. M4 is used for some real time operations.
Currently I am building the M4 part (cmake project) first and bitbake only adds the binary file to the image. What I want to do is to integrate the M4 build into the yocto build process. For this I need to specify a different compiler for the M4 recipe but I can't find any way to do it.
After reading yocto manual I think that writing custom do_compile method should work. But I guess there should be some way to use the existing cmake builder.
I think the multiconfig feature is the one you want, as long as both variants have their own MACHINE definition:
https://www.yoctoproject.org/docs/2.6/mega-manual/mega-manual.html#dev-building-images-for-multiple-targets-using-multiple-configurations
I have an embedded linux "proof-of-concept" project that wants to add some packages to an existing piece of hardware with a read-only filesystem. I am very new (1 week) to Yocto but it seems like it is possible. Looking for a general road map of how to achieve this, but any detailed strategy ideas would be helpful to keep in mind as I RTFYM.
It is a networked device, running on ARMv5t hardware.
64GB SD/MMC card is available (empty) and mounted.
telnet, nfs, busybox utils available.
no resident dev tools
The packages I need to add are openssl, python, zeromq, pyzmq, and perhaps other python modules in the future. I cannot place these into the rootfs because it is read-only, but they can reside on the sd card. I am trying to understand how to use Yocto to create this set of packages and collect them together as a build output. What I have so far:
EXTERNAL_TOOLCHAIN and meta-sourcery recipe is working
I can build python and pyzmq independently with bitbake -b
Don't know how to add pyzmq or other modules to python tree
How to build & collect just these items without building entire image?
The python part is running on the hardware but I just hand-copied it to the nfs folder. I am asking if this is a valid approach and if so, to add some directional detail. I hope I have provided enough information.