kernel configuration question

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#1

I have successfully built various angstrom kernel and root filesystem images using bitbake, but I still feel like I’m not fully understanding things. I’ve been reading the various documents and wikis, but so far I haven’t found the answer to the following questions. If anyone could provide an answer or a lead to finding the answer, I’d appreciate it.

  1. As far as I can tell, after I do a bitbake, like “bitbake console-image”, the results are left in directories under the “tmp” subdir, and they appear to be intermixed with lots of intermediate build files. Is there a way to extract just the final product into a clean tree, or am I just not looking in the right place?

  2. If I am building a different kernel (like MontaVista), using ‘make’ instead of ‘bitbake’, I can configure the kernel using “make gconfig” to edit the .config file. Is there a similar mechanism using bitbake, or do I need to edit the config files (which I think are stored as ‘defconfig’) by hand?

  3. Is there an automatic way to extract the kernel source from bitbake into a tree that is buildable via the standard kernel build tools using “make”, or is that not something that is designed to be possible?

I apologize if any of this stuff is obvious and I’m just missing it, but after days of reading, I haven’t found the answers.

Thanks again for any help,
Brett

#2

Brett Kuehner wrote:

1) As far as I can tell, after I do a bitbake, like "bitbake console-image", the results are left in directories under the "tmp" subdir, and they appear to be intermixed with lots of intermediate build files. Is there a way to extract just the final product into a clean tree, or am I just not looking in the right place?

You can get rid of most of the disk usage by deleting the work directory (but see below) I suspect that if you are done, stamps, pkgdata, and probably cache are also unnecessary. You'll only need cross and staging if you want to build things for it, and rootfs is is probably tar.gz'ed (or something) under deploy. To simply use the files you only need deploy, to compile you need cross and staging. So far as I understand it, anyway.

2) If I am building a different kernel (like MontaVista), using 'make' instead of 'bitbake', I can configure the kernel using "make gconfig" to edit the .config file. Is there a similar mechanism using bitbake, or do I need to edit the config files (which I think are stored as 'defconfig') by hand?

3) Is there an automatic way to extract the kernel source from bitbake into a tree that is buildable via the standard kernel build tools using "make", or is that not something that is designed to be possible?

Bitbake ends up using the standard kernel build process, it just copies a completed .config file shipped along with the build recipe. My kernel files are found under tmp/work/beagleboard-angstrom-linux-gnueabi/linux-omap-*/git

In principal you can modify the config file as you normally would and rebuild. You can use

bitbake -c compile -f linux
bitbake linux (or bitbake console-image to rebuild the whole thing)

Or if you want to build yourself, you can bitbake devshell to get a shell script that can be source'd to provide OE environment variables and macros. The result is in tmp/deploy/glibc/addons.

#3

That was extremely helpful, thank you. I figured there must be a
kernel directory in there somewhere, but there was so much other
stuff that I wasn't able to find it. But the path you gave is just
what I needed.

Brett