Re: CVS commit: src/sys/arch/x86/x86

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

Caveat: this is all opinion.  I'm not the one doing the work here.

>>>>         src/sys/arch/x86/x86: mpbios.c

>>>> Remove unaligned access to mpbios_page[]

>>>> sys/arch/x86/x86/mpbios.c:308:11, load of misaligned address 0xffff800031c7a413 for type 'const __uint16_t' which requires 2 byte alignment

>> Can we please do NOT do such stupid changes?

> Kernel Undefined Behavior Sanitizer detects various portability
> issues including alignment.

Portability issues are, in general, not issues when they are in code
that is inherently already nonportable - such as almost everything
under sys/arch/.

> Misaligned pointer is explicitly documented as undefined behavior in
> the C standard (C11 6.3.2.3 p7).

So what?  Do you have reason to think that sys/arch/x86 will at some
point be ported to a compiler (I would say "and architecture", but it's
already tightly bound to a very small set of CPU architectures) that
does something unexpected with that code?  Expecting the MD code in the
low levels of an OS to never produce formally implementation-defined or
undefined behaviour is a fool's dream.

Programs such as undefined-behaviour detectors are tools to serve us,
not shackles to bind us.  Intelligence should be applied when using
their results, including not expecting portability from inherently
nonportable code.

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