[Buildroot] [PATCH 1/2] package/glibc: add support for ARC700

[Alexey Brodkin]

Hi Thomas,

> > Even though ARC700 glibc port is very close to ARCv2 port, it is formally
> > another ABI that requires appropriate maintenance. That includes running
> > extensive glibc test-suite and fixing discovered issues and regressions.
> > That effort was considered impractical due to ARCompact ISA reaching EOL.
> > Besides ARC700 processors are usually found on very resource constrained
> > devices that tend to use uClibc if they run Linux.
> >
> > On the other hand adding ARC700 glibc support still can be useful for
> > development and testing purposes. This commit adds two glibc patches
> > that enable ARC700 support.
> 
> Hmm, this commit only adds one patch.

Correct, because that's all what's needed for ARC700 to be supported by glibc
as good as ARC HS processors are. Seriously, there're just a couple of
instructions which need to be changed (like use "trap0" instead of "trap_s 0")
and dynamic loader name is different ("/lib/ld-linux-arc700.so.2"). All the
rest is some configuration/infrastructural nonsense.

> Also, what is the upstream status of this patch?

As it is said in the patch itself, we decided to not officially maintain ARC700 
in glibc due to very strict rules in the upstream glibc community for supported
architectures and ABI's. But given minimal differences compared to ARCv2
(read "ARC HS") port, IMHO it's practical to have ARC700 support "downstream"
with a bit more relaxed requirements on maintenance activities... which doesn't
mean I'd like to throw stuff over the wall and never do anything about it.

> In order to make sure we can easily update glibc, I'm not too fan to have
> patches that are not upstream.

That's understood, but for many releases that change was equally applicable to
newer glibc versions (as we touch code which is rarely being modified) and even
now I re-based or refreshed this patch from 2.34 to 2.36 automatically with
only changes of hunk offsets (for the record, even before refresh, the patch
got applied to the current glibc in Buildroot only showing patch warnings
related to offsets).

That said, if you're not comfortable with the current maintenance status of
glibc for ARC700, we may drop it and limit ARC700 to only uClibc, otherwise
let's keep that patch until it seriously get in the way on glibc upgrade etc.

-Alexey