krb5.conf and 32 vs 64-bit plugins

[Benjamin Kaduk]

On Mon, 17 Aug 2015, Tomas Kuthan wrote:

> On 08/17/15 06:33 AM, Greg Hudson wrote:
> > On 08/14/2015 08:43 AM, Tomas Kuthan wrote:
> >> We would like to solve that by supporting $ISA place holder in the path,
> >> that would translate to '/64/' on 64-bit and to '/' on 32-bit. Hence the
> >> following (artificial) example would work fine for both:
> >>
> >>      module = pkinit:/lib/$ISA/site/preauth/pkinit.so
> >>
> >> Would MIT be willing to accept a patch implementing something along
> >> these lines?
> >
> > My concern is that different operating systems have done different
> > things with 32-bit and 64-bit libraries, even within the space of Linux
> > distributions.  Rather than a solution narrowly tailored to one
> > operating system, I would like a plan which can cover a broad range of
> > operating systems, preferrably one which doesn't add a lot of complexity
> > to the code.
> >
>
> Hi Greg,
>
> thank you for your reply.
>
> Just to clarify, with this proposal we are trying to address plugins in
> non-default library path (I should have made up a better example, such
> as "/opt/vendor/product/version/lib/plugins/$ISA/"). Default library
> path already works fine for both 32 and 64-bit.
>
> How about supporting the following macros, that would  be settable at
> configure with the following default values:
>
> #define ISA_STRING "/$ISA/"
> #define ISA_32 "/"
> #define ISA_64 "/64/"
>
> I believe this should offer enough flexibility.

I'm unconvinced that 32- and 64-bit (x86) are the only ABIs that need to
be considered.  ARM is an interesting case, with thumb-ABI as an option,
hard- or soft-float (not that we use much floating-point, but it's
illustrative of the ABI explosion), and other options once you start
permit running on different chips.  It really seems like something more
generic than 32 vs 64 bits is going to be needed.

-Ben