[OE-core] purpose of variables like "base_bindir_native"?

[Richard Purdie]

On Wed, 2016-11-30 at 06:34 -0500, Robert P. J. Day wrote:
>   i'm putting together a tutorial on the structure of the native
> sysroot and how it's built and variables involved, and was poking
> around in both bitbake.conf and native.bbclass, and i'm curious about
> one or two things.
> 
>   i could be totally wrong but it *seems* like there's native-related
> content in bitbake.conf that could be moved over to native.bbclass to
> reduce a little of the clutter. i'm perusing bitbake.conf and it's
> hard to keep track of some of the variables just because there's both
> native- and target- related settings in there. but i'll admit i
> haven't finished my inspection.
> 
>   on a more specific note, in the entire oe-core layer, there are two
> references to the variable "base_bindir_native" (formatted for
> aesthetics):
> 
> $ grep -rw base_bindir_native *
> meta/conf/bitbake.conf:base_bindir_native = "/bin"
> meta/conf/bitbake.conf:PATH_prepend =
>  "${COREBASE}/scripts:i
>  ${STAGING_BINDIR_TOOLCHAIN}:
>  ${STAGING_BINDIR_CROSS}:
>  ${STAGING_DIR_NATIVE}${sbindir_native}:
>  ${STAGING_BINDIR_NATIVE}:
>  ${STAGING_DIR_NATIVE}${base_sbindir_native}:
>  ${STAGING_DIR_NATIVE}${base_bindir_native}:"      <----- there
> 
>   so, given that that variable is set in bitbake.conf, and is only
> referenced in that same file, what's the point of making it a
> variable? doesn't hurt, of course, but when i see a variable, i
> normally assume it's because it might be modified later somewhere,
> but
> i don't see that happening here. is there a reason for it? same thing
> could be said for "base_sbindir_native" as well.
> 
>   thoughts?

Its really for consistency. We don't hardcode the other path
relationships and whilst that one is a minority, we've clearly decided
not to hardcode it either. The fact its not widely used compared to
some of its relatives is not really the point.

If we did hardcode it, I can imagine the question about why it wasn't
parametrised ;-).

Cheers,

Richard