bug#37818: [PATCH] Various FAQ updates

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Sat, 19 Oct 2019 14:58:53 +0200
> Cc: 37818@debbugs.gnu.org
> 
> Thanks.  I've attached a revised patch here according to your
> comments.

I have some, see below.

> I'm not sure what the file size limit is for
> --with-wide-int on 32-bit builds or 64-bit builds, so that still needs
> adding.  Could someone please give the exact numbers or tell me where
> I can find them?

See below.

> +Emacs has an inherent fixed limitation on the size of buffers.

I'd suggest to say that the limitation is more strict that the maximum
size of objects supported by programs with the same architecture,
because otherwise this sentence might be misunderstood.

>                                                                  The
> +maximum buffer size on 32-bit machines is 512 MBytes beginning with
> +version 23.2.  If Emacs was built using the @code{--with-wide-int}
> +flag, the maximum buffer size on 32-bit machines is ***FIXME***
> +MBytes.

The number here is 2GB.

> +This limitation imposes a size limit on visiting files, which is
> +roughly half the buffer limit due to things like decoding of multibyte
> +characters.  When visiting compressed archives, the file size
> +limitation will be smaller than that due to decompression.
> +
> +Unless you want to visit unusually large files, this should only be an
> +issue on 32-bit machines.  Emacs compiled on a 64-bit machine can
> +handle much larger buffers.

The limit value for 64-bit builds is that of most-positive-fixnum.