On Monday, 29 December 2025 11:53:08 Brasilia Standard Time Andrey Semashev
via Std-Proposals wrote:
> Why do you need a separate main2() if you can already do all of this in
> the standard main()?

On Linux, you don't even need that. Just set your linker arch to x86-64-v2
(SSE4.2) and glibc will refuse to run your application if it doesn't match.

>From elf.h:

/* GNU_PROPERTY_X86_ISA_1_V2: GNU_PROPERTY_X86_ISA_1_BASELINE,
   CMPXCHG16B (cmpxchg16b), LAHF-SAHF (lahf), POPCNT (popcnt), SSE3,
   SSSE3, SSE4.1 and SSE4.2. */
#define GNU_PROPERTY_X86_ISA_1_V2 (1U << 1)

There are now several Linux distributions that require v2. For example,
openSUSE 16.0 and Slowroll, Red Hat Enterprise Linux 9. I've seen some
discussion that RHEL10 should even be v3.

-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
  Principal Engineer - Intel Data Center - Platform & Sys. Eng.