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