what is the value of 'BBPATH ?= ""' in layer.conf?
perusing some wind river layers, and in the layer.conf file here:
https://github.com/WindRiver-OpenSourceLabs/wr-kernel/blob/LB21_7.0_RCPL0002/conf/layer.conf
i see the opening snippet:
BBPATH ?= ""
# We have a conf and classes directory, add to BBPATH
BBPATH := "${LAYERDIR}:${BBPATH}"what is the purpose of that initial assignment
BBPATH ?= ""
if that variable has no value, won't it just expand to the empty string so that the eventual effect is the same? or is there something more subtle happening here?
rday
Signature · 7 lines
========================================================================
Robert P. J. Day Ottawa, Ontario, CANADA
http://crashcourse.ca
Twitter: http://twitter.com/rpjday
LinkedIn: http://ca.linkedin.com/in/rpjday
========================================================================Quoted 7 lines · Robert P. J. Day
perusing some wind river layers, and in the layer.conf file here:
https://github.com/WindRiver-OpenSourceLabs/wr-kernel/blob/LB21_7.0_RCPL0002/conf/layer.conf
i see the opening snippet:
Quoted 7 lines
BBPATH ?= "" # We have a conf and classes directory, add to BBPATH BBPATH := "${LAYERDIR}:${BBPATH}"what is the purpose of that initial assignment
BBPATH ?= ""
There would be a warning when BBPATH is null, but that had been fixed, so we don't need it nowadays.
// Robert
Quoted 7 lines
if that variable has no value, won't it just expand to the empty string so that the eventual effect is the same? or is there something more subtle happening here?
rday
Quoted 14 lines · Robert Yang
Quoted 11 lines · Robert P. J. Day
perusing some wind river layers, and in the layer.conf file here:
https://github.com/WindRiver-OpenSourceLabs/wr-kernel/blob/LB21_7.0_RCPL0002/conf/layer.conf
i see the opening snippet:
BBPATH ?= "" # We have a conf and classes directory, add to BBPATH BBPATH := "${LAYERDIR}:${BBPATH}"
Quoted 8 lines
Quoted 3 lines
what is the purpose of that initial assignment
BBPATH ?= ""There would be a warning when BBPATH is null, but that had been fixed, so we don't need it nowadays.
// Robert
i thought as much, i just wanted to be sure. i am a rabid minimalist
in that, if a line has no value, it should be removed, mostly to avoid confusing people like me. :-) i noticed at least a couple WR-OSL layers that had that construct, you can decide if you care enough about it to clean it up. thanks for the clarifiation.
rday
Signature · 7 lines
========================================================================
Robert P. J. Day Ottawa, Ontario, CANADA
http://crashcourse.ca
Twitter: http://twitter.com/rpjday
LinkedIn: http://ca.linkedin.com/in/rpjday
========================================================================Quoted 23 lines · Robert P. J. Day
Quoted 21 lines · Robert Yang
Quoted 7 lines · Robert P. J. Day
perusing some wind river layers, and in the layer.conf file here:
https://github.com/WindRiver-OpenSourceLabs/wr-kernel/blob/LB21_7.0_RCPL0002/conf/layer.conf
i see the opening snippet:
Quoted 7 lines
BBPATH ?= "" # We have a conf and classes directory, add to BBPATH BBPATH := "${LAYERDIR}:${BBPATH}"what is the purpose of that initial assignment
BBPATH ?= ""There would be a warning when BBPATH is null, but that had been fixed, so we don't need it nowadays.
Quoted 7 lines
Quoted 1 line
// Robert
i thought as much, i just wanted to be sure. i am a rabid minimalist
in that, if a line has no value, it should be removed, mostly to avoid confusing people like me. :-) i noticed at least a couple WR-OSL layers that had that construct, you can decide if you care enough about it to clean it up. thanks for the clarifiation.
Thanks, we have cleaned that up in new release.
// Robert
Quoted 3 lines
rday
Quoted 10 lines · Robert P. J. Day
perusing some wind river layers, and in the layer.conf file here:
https://github.com/WindRiver-OpenSourceLabs/wr-kernel/blob/LB21_7.0_RCPL0002/conf/layer.conf
i see the opening snippet:
BBPATH ?= "" # We have a conf and classes directory, add to BBPATH BBPATH := "${LAYERDIR}:${BBPATH}"
(for the -first- layer defined)
BBPATH := "${LAYERDIR}:${BBPATH}"
will result in a warning or error because the ${BBPATH} can't be expanded.
There was a commit late 2013 to OE-Core and most related layers that turned this into a append (or in this case prepend):
BBPATH =. "${LAYERDIR}:"
This is stop the need for the BBPATH and work properly.
LAYERDIR is always expanded when used, so no need for the :=
--Mark
Quoted 10 lines
what is the purpose of that initial assignment
BBPATH ?= ""
if that variable has no value, won't it just expand to the empty string so that the eventual effect is the same? or is there something more subtle happening here?
rday