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

[Yousong Zhou]

On 14 September 2017 at 19:06, Robert P. J. Day <rpjday at crashcourse.ca> wrote:
>
>   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 from back then is no longer valid, so i just tossed that test out of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

I have been using an old debian wheezy virtual machine for years when
working on OpenWrt/LEDE...  It just works.  If you are working alone
and man power is a scarce and precious resource, I would say it's very
likely not worth the time and effort: will the gain in bringing up the
old repo in new dev environment really work out?

my two cents,
                yousong