[OE-core] what means IMAGE_ROOTFS_EXTRA_SPACE_append += "+ 3000000"?

[Jérémy Rosen]

On 17/08/2016 16:01, Robert P. J. Day wrote:
>    as in, what's with the "+" in that "+ 3000000" value? i've never
> seen that before, and i took a quick look under classes/ to try to
> figure out what's happening, but i'm still confused.
you're reading too much into this

"+ 3000000" will append the string "+ 3000000" to the string contained 
in the IMAGE_ROOTFS_EXTRA_SPACE variable

I am not sure who consumes that variable, but I assume it's something 
that's able to do math and will properly compute the final value.

you can always run "bitbake -e core-image-kernel-dev" in a pager an look 
at the final value to see what's happening...

>    this is all in aid of the aforementioned "+=" cleanup, and i can see
> some inconsistency as to whether there should be a leading space or
> not in the assigned value:
>
> classes/rootfs_rpm.bbclass:IMAGE_ROOTFS_EXTRA_SPACE_append = "${@bb.utils.contains("PACKAGE_INSTALL", "smartpm", " + 102400", "" ,d)}"
> recipes-core/images/core-image-minimal.bb:IMAGE_ROOTFS_EXTRA_SPACE_append = "${@bb.utils.contains("DISTRO_FEATURES", "systemd", " + 4096", "" ,d)}"
> recipes-extended/images/core-image-kernel-dev.bb:IMAGE_ROOTFS_EXTRA_SPACE_append += "+ 3000000"
>
> and the YP reference manual says nothing about a possible "+":
>
> http://www.yoctoproject.org/docs/latest/ref-manual/ref-manual.html#var-IMAGE_ROOTFS_EXTRA_SPACE
>
> rday
>