[OE-core] a few questions about "COMPATIBLE_MACHINE" variable

[Robert P. J. Day]

On Sun, 26 Feb 2017, Robert P. J. Day wrote:

... big snip ...

> is there a style guide entry for proper use of COMPATIBLE_MACHINE?
> having the manuals make suggestions that are potentially confusing
> to inexperienced users seems like a bad idea.

  for fun, i did a quick grep in the oe-core layer:

meta/conf/documentation.conf:COMPATIBLE_MACHINE[doc] = "A regular expression that resolves to one or more target machines with which a recipe is compatible."
meta/recipes-kernel/linux/linux-yocto-tiny_4.4.bb:COMPATIBLE_MACHINE = "(qemux86$)"
meta/recipes-kernel/linux/linux-yocto-rt_4.1.bb:COMPATIBLE_MACHINE = "(qemux86|qemux86-64|qemuarm|qemuppc|qemumips)"
meta/recipes-kernel/linux/linux-yocto-rt_4.9.bb:COMPATIBLE_MACHINE = "(qemux86|qemux86-64|qemuarm|qemuppc|qemumips)"
meta/recipes-kernel/linux/linux-yocto-tiny_4.8.bb:COMPATIBLE_MACHINE = "(qemux86$)"
meta/recipes-kernel/linux/linux-yocto-rt_4.8.bb:COMPATIBLE_MACHINE = "(qemux86|qemux86-64|qemuarm|qemuppc|qemumips)"
meta/recipes-kernel/linux/linux-yocto_4.4.bb:COMPATIBLE_MACHINE = "qemuarm|qemuarm64|qemux86|qemuppc|qemumips|qemumips64|qemux86-64"
meta/recipes-kernel/linux/linux-yocto-dev.bb:COMPATIBLE_MACHINE = "(qemuarm|qemux86|qemuppc|qemumips|qemumips64|qemux86-64)"
meta/recipes-kernel/linux/linux-yocto-tiny_4.1.bb:COMPATIBLE_MACHINE = "(qemux86$)"
meta/recipes-kernel/linux/linux-yocto-rt_4.4.bb:COMPATIBLE_MACHINE = "(qemux86|qemux86-64|qemuarm|qemuppc|qemumips)"
meta/recipes-kernel/linux/linux-dummy.bb:#COMPATIBLE_MACHINE = "your_machine"
meta/recipes-kernel/linux/linux-yocto_4.9.bb:COMPATIBLE_MACHINE = "qemuarm|qemuarm64|qemux86|qemuppc|qemumips|qemumips64|qemux86-64"
meta/recipes-kernel/linux/linux-yocto_4.1.bb:COMPATIBLE_MACHINE = "qemuarm|qemuarm64|qemux86|qemuppc|qemumips|qemumips64|qemux86-64"
meta/recipes-kernel/linux/linux-yocto_4.8.bb:COMPATIBLE_MACHINE = "qemuarm|qemuarm64|qemux86|qemuppc|qemumips|qemumips64|qemux86-64"
meta/recipes-kernel/linux/linux-yocto-tiny_4.9.bb:COMPATIBLE_MACHINE = "(qemux86$)"
meta/classes/base.bbclass:    need_machine = d.getVar('COMPATIBLE_MACHINE')
meta/classes/base.bbclass:            raise bb.parse.SkipPackage("incompatible with machine %s (not in COMPATIBLE_MACHINE)" % d.getVar('MACHINE'))

  so as long as i understand correctly the re.match() anchoring, some
of the above assignments can definitely be tightened up with no change
in behaviour, correct? not saying i'm going to run off and submit a
patch for that, since i rather like chris' suggestion that the
matching be tightened up to catch inadvertently sloppy matching, as
long as that doesn't break all kinds of stuff.

  thoughts?

rday

p.s. hey, COMPATIBLE_HOST seems to work the same way, so it seems
there would be no value in appending ".*" to the end of any choice so,
for example:

  argp-standalone_1.3.bb:COMPATIBLE_HOST = ".*-musl.*"

could be more simply written as:

  argp-standalone_1.3.bb:COMPATIBLE_HOST = ".*-musl"

yes?

-- 

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Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
LinkedIn:                               http://ca.linkedin.com/in/rpjday
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