The importance of base_prefix

Recently I started into converting our -native recipes from oe-classic into oe-core. First try I got a strange error from tar about the path not existing. The path it wanted looked crazy, something like /home/user/Angstrom/build/tmp-angstrom_2010_x-uclibc/work/armv7a-vfp-angstrom-linux-uclibceabi/mypackage-1.0-r0/image///home/user/Angstrom/build/tmp-angstrom_2010_x-uclibc/sysroots/mymachine. Debugging the scripts lead me into a maddening maze. The problem seemed to be emanating from the sstate creation tasks.

It turns out that we were not respecting the ${base_prefix} variable when doing our install. The recipe we were using installs into a non-standard location, so we were installing into something like ${D}/opt/custom-place/ but native recipes actually set the base_prefix to a really strange value like /home/user/Angstrom/build/tmp-angstrom_2010_x-uclibc/sysroots/mymachine. For reference, in normal embedded builds, ${base_prefix} is an empty string.

The fix was simple. Install instead to ${D}${base_prefix}/opt/custom-place/ which installs to the same place it always had during embedded builds, and the long path that tar was looking for during -native builds of the recipe.

Happy building!

What is this blog about exactly?

I'm glad you asked! This blog will be all about my challenges and solutions in creating Embedded Linux platforms, and my musings on computer technology. When I first joined up as a firmware engineer, I was terrified. How could I ever work effectively on such complicated systems? It has been a wild ride and everyday brings new and exciting problems. I can't wait to share them all with you.