[LEDE-DEV] is it feasible to use a recent linux distro & LEDE to build openwrt 15.05.1?

[Robert P. J. Day]

  here's hoping someone can give me a short answer on whether this is
possible, or whether it's just not worth the trouble.

  i was recently handed an existing openwrt-based project, which is
based on openwrt 15.05.1. the problem (unsurprisingly) is that some of
the structure of openwrt that old is that parts of it are simply
unbuildable with a modern linux distro, like my fully-updated fedora
26 system.

  when i first tried to build that project, the first failure was
simply trying to build the toolchain, as gcc 6 was unable to compile
the older gcc 4 that was being selected for the toolchain. another
tweak was to patch glib2 to be buildable by gcc 6, that sort of thing.

  once i got past that, next was simply ignoring the bazillion
"WARNING: No feed for package 'XXXX' found, maybe it's already part of
the standard packages?" messages.

  next, the prereq-build.mk test for "git" failed, given that the test
from back then is no longer valid, so i just tossed that test out of
that makefile.

  at that point, now that i've upgraded, the newer gcc7 failed to
compile tools/mkimage as the compiler complained (unsurprisingly)
about a missing include/linux/compiler-gcc7.h header file, so i threw
one in and resumed, to get compilation errors in
u-boot-2014.10/lib/rsa/ras-sign.c:

.../rsa-sign.c:279:21: error: dereferencing pointer to incomplete type 'RSA {aka struct rsa_st}'
  if (BN_num_bits(key->e) > 64)

etc ... etc ... you get the idea.

  the other approach i tried was, since changes to 15.05.1 to support
the board in question had been made in a git repo, i figured i could
just go back and effectively rebase all the board support changes on
top of LEDE, but:

1) the commits are totally chaotic and incomprehensible, and
2) the folks in charge are adamantly opposed to trying to bring this
source up to date -- "it works, don't touch it"

  at the moment, the build succeeds only because it's being done in a
VM running an old version of ubuntu that's compatible with 15.05.1.
yuck.

  i would dearly love to somehow get this code up-to-date with LEDE,
but i'm starting to think there's no pleasant way to do that.

  thoughts?

rday

-- 

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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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