[OE-core] can pkg_{pre, post}rm functions be run at all for image creation?

[Paul Eggleton]

On Sunday 03 August 2014 02:56:04 Robert P. J. Day wrote:
> On Sat, 2 Aug 2014, Khem Raj wrote:
> > On 14-08-02 15:57:00, Robert P. J. Day wrote:
> > > On Sat, 2 Aug 2014, Khem Raj wrote:
> > > > On Sat, Aug 2, 2014 at 9:34 AM, Robert P. J. Day 
<rpjday at crashcourse.ca> wrote:
> > > > > say, pkg_prerm() functions would never be written with respect to
> > > > > the
> > > > > variable ${D}, which would be relevant only during image creation.
> > > > > but
> > > > > i can see things like this in sysklogd.inc:
> > > > > 
> > > > > pkg_prerm_${PN} () {
> > > > > 
> > > > >         if test "x$D" = "x"; then
> > > > 
> > > > note that its not ${D} (bitbake context) but $D which is evaluated
> > > > in the context when the script is run.
> > > > 
> > >   i still don't understand ... what are the possible values of $D
> > > 
> > > here, and what would they represent?
> > 
> > At build time it will not be expanded by bitbake like ${D} is. but
> > during image creation it will be. But when doing on-device install
> > of this package $D will be empty. Its a way to differentiate actions
> > during image creation and on-device install/update/remove
> 
>   but the yocto dev manual states pretty clearly that pkg_prerm and
> pkg_postrm functions are *not* used during image creation. so you're
> saying they are? under what circumstances?

They wouldn't normally be. You could in theory issue some package removal 
commands as part of postprocessing on the image but I can't see much use for 
that given we have things like PACKAGE_EXCLUDE now.

Khem was simply correcting your reference to ${D}. I can only imagine the 
example you gave is just belt-and-braces to make sure it could never be run 
outside the context of the real target.

Cheers,
Paul

-- 

Paul Eggleton
Intel Open Source Technology Centre