Re: [MIT-Scheme-devel] Ubuntu 11.04 and FE_DFL_ENV.

[Taylor R Campbell]

   Date: Sat, 11 Jun 2011 13:05:18 -0700
   From: Matt Birkholz <address@hidden>

   Let me sing it for you, Brother.  I "fixed" this easily enough and
   verified, via debugging traces and fegetexcept() in gdb, that ALL
   exceptions were masked.  Yet gdb said I was trapping in Pango, looking
   for a font or sump'n.

Gee, OK.  My only worry is that the userland libc might disagree with
Scheme's fenv cruft (e.g., maybe libc wants to store its own cache of
trapped or raised exceptions or something).  Not likely with glibc or
any BSD libc I'm aware of, but that's why I didn't just always use
Scheme's fenv cruft on x86.  Since you limited BROKEN_FENV to Linux,
where all the world is glibc, it'll probably be OK.

   > Can you set a breakpoint in gdb on alienate_float_environment, both
   > with libc's fe* and with Scheme's fe*, and step through the machine
   > instructions to compare what they do differently?

   Of course!  Can't we all?  :-)

Well, I don't have any systems running Ubuntu handy, so...  If I
remember when I have some time, I'll try this out on NetBSD and maybe
Fedora and Debian.