On 6/9/26 12:03 PM, Zack Weinberg wrote:
On Tue, Jun 9, 2026, at 10:28 AM, Joel Sherrill wrote:
One of the RTEMS.org GSoC projects is bringing the safelibc
(https://github.com/rurban/safeclib) to RTEMS. This library
implements the C11 and later Annex K Bounds Checking functions.
I can't make you stop, but I urge you to reconsider whether this project
is actually a good idea. The Annex K functions do not actually do the
job they were meant to do -- "dropping in" the Annex K equivalents of
each core C runtime function, *at best*, only converts bugs into
different bugs. Continuing to put effort into Annex K encourages the
erroneous belief that a program written using exclusively these
functions is somehow "safer" than a program that uses the traditional
functions. In all cases where it is genuinely impossible to use a core
C library function without the program having a bug, there is an
existing alternative within core C that can be used.
Agreed.
Please see:
Document number: N1967
"Field Experience With Annex K — Bounds Checking Interfaces"
Authors: Carlos O'Donell, Martin Sebor
https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1967.htm
It's especially important to disabuse *students* of this erroneous
belief because several influential sources (notably, Microsoft's "Visual
Studio" tools, which are very likely to be a student's first exposure to
C these days) push said belief on students. I would not have accepted
this GSoC project in the first place.
That said ...
I would appreciate any pointers to what is required of a library to
support being built multilib. A simple example would be even better.
... Unfortunately, as far as I know, none of the Autotools have any built-
in support for multilib builds. The usual workaround is to have a higher-
level Makefile or build script that invokes the library build several
times with different CFLAGS, prefix, etc. If you don't want your
student to blow a huge amount of time and effort on build system issues,
I would go with that approach.
That's what we do with glibc and the GNU Toolchain in general. We iterate
one level higher and build libraries multiple times with different
hardware configurations. Then each library is then dropped into a
glibc-hwcaps based directories where ld.so loads the multilib based on
hardware capabilities.
For this specific task, [email protected] is probably a better place
to get advice than autoconf@.
--
Cheers,
Carlos.
