[yocto] couple questions about kernel dev manual, section 2

[Robert P. J. Day]

On Sat, 13 Apr 2013, Tom Zanussi wrote:

> On Sat, 2013-04-13 at 11:20 -0400, Robert P. J. Day wrote:
> > some oddities in section 2.2.1 of the current kernel dev manual.
> > first, there's:
> >
> > "The append file should initially contain the following text:
> >
> >      FILESEXTRAPATHS := "${THISDIR}/${PN}"
> >
> >   i was under the impression that the standard line would be:
> >
> >      FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
> >
> > would it not? to make sure you can support potential layers on top of
> > layers, no?  if you absolutely *know* that won't happen, then, sure,
> > that will work, but i think the wording above is unnecessarily
> > restrictive.
>
> Right, that should be changed to match the recommendation in the Poky
> Reference manual.
>
> >   also, right underneath that, one reads:
> >
> > "If you add any new files that modify the kernel recipe, you need to
> > place them in your layer in the following area:
> >
> >      <your-layer>/recipes-kernel/linux/linux-yocto/"
> >
> > IIRC, you *can* put them there but you don't *need* to. in fact, tom
> > zanussi's kernel labs place extra files simply under a "files/"
> > subdirectory (after setting FILESEXTRAPATHS to pick up that
> > directory). so, again, some wording that is unnecessarily strong and
> > somewhat misleading.
> >
> >   thoughts?
> >
>
> That text assumes you've used (the corrected) from the paragraph above:
>
> FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"

  that may be true, but it's not clear from the text that that claim
is based on the earlier (corrected) setting.  i just get itchy when i
see inappropriately strong claims.

> which means you do need to put the files in the linux-yocto/ subdir (for
> a linux-yocto bbappend), since we're dealing with a .bbappend here.
>
> If we were talking about a recipe, then yes, we wouldn't *need* to put
> them there but could also put them in any of the default subdirs such as
> files/.  There's a little more discussion about it here:
>
> https://lists.yoctoproject.org/pipermail/yocto/2013-February/014419.html
>
> Seems like it might be good to explicitly explain all this or at least
> point out the difference and help avoid the confusion...

  once upon a time, i dug into this whole FILESEXTRAPATHS issue and i
was surprised to find how it worked, which i documented:

http://www.crashcourse.ca/wiki/index.php/FILESEXTRAPATHS_and_bbappend_files

it may be that i have to revisit that to make sure that page is up to
date, but i don't think any of the documentation makes it abundantly
clear how FILESEXTRAPATHS truly works -- that it adds an entire *set*
of additional directories to FILESPATH:

http://www.crashcourse.ca/wiki/index.php/FILESEXTRAPATHS_and_bbappend_files#Examining_FILESPATH.2C_and_how_FILESEXTRAPATHS_works

certainly, the variable glossary doesn't seem to mention that:

http://www.yoctoproject.org/docs/latest/ref-manual/ref-manual.html#var-FILESEXTRAPATHS


unless, of course, i've misunderstood this completely.

rday

-- 

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

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