On 7/22/14, 11:53 AM, Robert P. J. Day wrote:
On Tue, 22 Jul 2014, Christopher Larson wrote:
On Tue, Jul 22, 2014 at 9:36 AM, Robert P. J. Day <[email protected]> wrote:
quite possibly another silly question, but i'm perusing poky's
version of bitbake.conf and i see this:
DEPLOY_DIR ?= "${TMPDIR}/deploy"
DEPLOY_DIR_TAR = "${DEPLOY_DIR}/tar"
DEPLOY_DIR_IPK = "${DEPLOY_DIR}/ipk"
DEPLOY_DIR_RPM = "${DEPLOY_DIR}/rpm"
DEPLOY_DIR_DEB = "${DEPLOY_DIR}/deb"
DEPLOY_DIR_IMAGE ?= "${DEPLOY_DIR}/images/${MACHINE}"
DEPLOY_DIR_TOOLS = "${DEPLOY_DIR}/tools"
now, what is the value of using "?=" to set DEPLOY_DIR_IMAGE, rather
than just "=". i know what "?=" represents, but i normally expect to
see it in a context where someone might have set it earlier to some
other value, but this is in bitbake.conf, before any of the "include"
or "require" directives to pull in any of the other .conf files. so in
the midst of all those other DEPLOY_DIR_* hard assignments, why is the
images directory a conditional install?
s/install/define/
um, quite so. :-P
If there's a ?= done before any includes in bitbake.conf, either its
position in the file has changed, or it's set that way to allow the
user to add those variables to the env whitelist and set them in the
environment, as the env is set before bitbake.conf is parsed.
ah, gotcha. so the obvious question is, who decides which variables
merit this sort of behaviour and which don't? why two variables out of
the DEPLOY_DIR_* variables and not the rest? seems sort of arbitrary.
Who, whoever sends patches with a need.
I know I've used both the DEPLOY_DIR and DEPLOY_DIR_IMAGE before to simplify a
few things on the command line.. (but I don't use them regularly).
The others being based on those have not caused me problems the few times I've
wanted to override it from the command line.
--Mark
rday
--
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