Intel i7-12800H and march=alderlake

[NathanZachary]

Hello,

I have a laptop with an Intel i7-12800H processor, which should be Alder Lake. During the base system installation, though, I had to go with "march=native" instead of "march=alderlake" as the latter resulted in even basic utilities like pciutils throwing "Illegal instruction" errors. Does anyone have GCC documentation that might explain the problem, or a way to see the specific differences between the two arch declarations?

Thank you.

Cheers,
Nathan Zachary
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[Ionen]

Not familiar with Adler Lake's situation, but -march=exact is the generic definition of it, and the cpu may not necessarily support every instructions from that (it could also potentially support more).

like, -march=haswell enables -mavx2 (haswell was the first to support that), but forget avx2, my haswell minipc has not even avx1 support due to using a gimped laptop cpu (grep avx /proc/cpuinfo returns nothing)

That's why if cross-compiling / distcc or so, you're better off using app-misc/resolve-march-native to get the exact set, for my haswell that's roughly a simplified: -march=haswell -mabm -mno-avx -mno-bmi -mno-f16c -mno-fma -mno-xsave -mno-xsaveopt. And if not cross-compiling, just stick to -march=native on arches that allow it.

[mike155]

Run the commands below on your laptop to see the specific differences between the two arch declarations:

[NathanZachary]

Thank you mike155 for the recommendation. I didn't expect to see such a difference between 'native' and 'alderlake' considering this is a i7-12800H processor: