Bug 205663 Clang getting Bus Errors (arm SCLTR Bit[12]==1 context): Reported fixed on llvm's trunk

[Ian Lepore]

On Tue, 2016-01-05 at 12:05 -0800, Russell Haley wrote:
> On Tue, Jan 5, 2016 at 10:53 AM, Ian Lepore <ian at freebsd.org> wrote:
> > 
> > On Tue, 2016-01-05 at 11:35 -0700, Warner Losh wrote:
> > > On Tue, Jan 5, 2016 at 11:27 AM, Mark Millard <
> > > markmi at dsl-only.net>
> > > wrote:
> > > 
> > > > llvm.org's Bugzilla reports that clang trunk has been fixed and
> > > > clang 3.8
> > > > will contain the fixes:
> > > > 
> > > > James Molloy changed bug 25958
> > > > What    Removed Added
> > > > Status  NEW     RESOLVED
> > > > Resolution      ---     FIXED
> > > > Comment # 8 on bug 25958 from James Molloy
> > > > Hi Mark,
> > > > 
> > > > Thanks for your detailed investigation. I can confirm that this
> > > > is
> > > > fixed on
> > > > trunk and therefore will be fixed for LLVM 3.8.
> > > > 
> > > > The fixes were done for SPARC, which requires strict accesses
> > > > much
> > > > as ARM
> > > > does
> > > > with SCTLR=1.
> > > > 
> > > > There was a sequence of commits by James Knight that fixed
> > > > these,
> > > > but an
> > > > example is http://reviews.llvm.org/rL242554 .
> > > > 
> > > > The fixes were in a similar vein to yours, but required changes
> > > > in
> > > > fewer
> > > > places
> > > > and there were a few more sticky issues to solve too. I'll CC
> > > > James
> > > > here in
> > > > case he wants to comment on the current state of the clang
> > > > codebase
> > > > for
> > > > self-hosting in a strict alignment environment.
> > > > 
> > > > Cheers,
> > > > 
> > > > James
> > > > 
> > > 
> > > There's a projects/clang-380-import that you might want to try...
> > 
> > It's a non-starter for us, because unfortunately they appear to
> > have
> > removed support for the -arm-use-movt=0 command line option, so now
> > we
> > can't build ubldr or kernel modules.
> 
> Does this mean FreeBSD can't ever move to clang 3.8?
> 
> Russ

No, it means we have to figure out how we're going to fix or workaround
the situation before clang 3.8 can get moved from its experimental
branch into -current.  Whatever we come up with, we can make a local
patch, and submit the change back upstream.

-- Ian