Hi, On 2023-04-14 13:21:33 -0400, Tom Lane wrote: > Since the direct I/O commit went in, buildfarm animals > curculio and morepork have been issuing warnings like > > hashpage.c: In function '_hash_expandtable': > hashpage.c:995: warning: ignoring alignment for stack allocated 'zerobuf' > > in places where there's a local variable of type PGIOAlignedBlock > or PGAlignedXLogBlock. I'm not sure why only those two animals > are unhappy, but I think they have a point: typical ABIs don't > guarantee alignment of function stack frames to better than > 16 bytes or so. In principle the compiler could support a 4K > alignment request anyway by doing the equivalent of alloca(3), > but I do not think we can count on that to happen.
Hm. New-ish compilers seem to be ok with it. Perhaps we should have a configure check whether the compiler is OK with that, and disable direct IO support if not? Greetings, Andres Freund
