[OE-core] a few more picky questions about COMPATIBLE_MACHINE usage

[Robert P. J. Day]

On Mon, 27 Feb 2017, Andre McCurdy wrote:

> On Mon, Feb 27, 2017 at 10:53 AM, Robert P. J. Day
> <rpjday at crashcourse.ca> wrote:
> > On Mon, 27 Feb 2017, Phil Blundell wrote:
> >
> >> On Mon, 2017-02-27 at 09:09 -0500, Robert P. J. Day wrote:
> >> >  # webkit-efl isn't available for < armv7a
> >> >  COMPATIBLE_MACHINE = "(-)"
> >> >   COMPATIBLE_MACHINE_x86 = "(.*)"
> >> >   COMPATIBLE_MACHINE_x86-64 = "(.*)"
> >> >   COMPATIBLE_MACHINE_armv7a = "(.*)"
> >> >
> >> >   first, that comment seems out of date as it makes no mention of
> >> > MIPS
> >> > or ppc, but that's just being picky.
> >> >
> >> >   next, i assume the line:
> >> >
> >> >   COMPATIBLE_MACHINE = "(-)"
> >> >
> >> > is to initialize the set of compatible machines to the empty set,
> >> > yes?
> >>
> >> I think the intent is to set it to a string that "can't possibly
> >> ever match".
> >
> >   right, that's what i suspected.
> >
> >> >
> >>   i next assume that lines of the form:
> >> >
> >> >   COMPATIBLE_MACHINE_x86 = "(.*)"
> >> >
> >> > are meant to indicate that if that MACHINE_OVERRIDES comparison
> >> > succeeds, then all possible targets are compatible, is that right?
> >> > however, given precisely those lines above, is it not equivalent to
> >> > just write:
> >> >
> >> >   COMPATIBLE_MACHINE = "(x86|x86-64|armv7a)"
> >>
> >> No, because "armv7a" is not a MACHINE.  It would be more equivalent
> >> to write
> >>
> >> COMPATIBLE_HOST = "armv7a-.*"
> >>
> >> but even this would not be quite the same because it would fail to
> >> match "cortexa15-linux" for example.  Actually that's not a very
> >> good example because cortexa15 is armv7ve not armv7a, but you get
> >> the idea.
> >
> >   i'm going to disagree here, i never suggested "armv7a" was a
> > "machine" (in the sense of having a defining armv7a.conf file). i said
> > it was part of MACHINE_OVERRIDES, and therefore *would* be considered
> > a matching "machine" for the purposes of COMPATIBLE_MACHINE.
> >
> >   as another example, there is no such machine as a "qoriq", but that
> > is considered a valid choice for COMPATIBLE_MACHINE since several
> > actual machine definition files do this:
> >
> >   MACHINEOVERRIDES =. "qoriq:"
> >
> > am i making sense?
>
> I think so. However, note that ARM is somewhat of a special case in
> that it includes over-rides derived from TUNE_FEATURES in
> MACHINEOVERRIDES (although MIPS has recently started to do so too). In
> the general case (and especially in the context of COMPATIBLE_MACHINE)
> it's probably better to think of MACHINEOVERRIDES as containing just
> the machine name and perhaps a SOC family.
>
> (Maybe it would be clearer if over-rides derived from TUNE_FEATURES
> were placed in a dedicated variable, e.g. TUNINGOVERRIDES, rather than
> being crammed into MACHINEOVERRIDES?).

  cripes ... this was supposed to be a quick clarification. :-) i'll
try to summarize all of this in one place to see if i understand it
all correctly.

rday

-- 

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

Twitter:                                       http://twitter.com/rpjday
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