[Info-vax] x86-64 data aligment / faulting

[gah4]

On Friday, February 25, 2022 at 1:53:45 PM UTC-8, Mark Daniel wrote:
> Alpha and Itanium had data alignment requirements with penalties for 
> faulting. Does x86-64? Is sys$start_align_fault_report() et al. still 
> relevant? 

Ordinary instructions for x86 and x86-64 allow unaligned access.

Interlocked instructions, such as CMPXCHG16B require aligned
memory operands, in this case on a 16 byte boundary.

Interlocked operations allow for read-modify-write without allowing
any other task or thread, on any processor, in between.