bug#37818: [PATCH] Various FAQ updates

[Stefan Kangas <stefan@marxist.se>]

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Eli Zaretskii <eliz@gnu.org> writes:

> > 1. Remove section on how to enable the default behaviour of having the
> > region highlighted, which is probably not a frequently asked question.
>
> OK.

Thanks, pushed to master as commit 11c3ec3df6a.

> > 2. Remove information on large files in ancient versions of Emacs that
> > would only confuse new users.  This leaves in only the information on
> > the relatively recent versions of Emacs.
>
> IMO, this section should first tell that Emacs has an inherent fixed
> limitation on the size of buffers, as that is not something people
> assume nowadays.  It should cite the limitation separately for 32-bit
> builds, 32-bit builds --with-wide-int, and 64-bit builds.  Then it
> should say that this limitation also imposes size limit on visiting
> files, but the file-size limit is roughly about half the buffer limit,
> due to decoding and other stuff.  I would also mention visiting
> compressed archives, because the size limitation might be hit half-way
> through decompression.

Thanks.  I've attached a revised patch here according to your
comments.  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?

Best regards,
Stefan Kangas

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From 23317e478094d523f836d0ee97a9fff7dfcc6503 Mon Sep 17 00:00:00 2001
From: Stefan Kangas <stefankangas@gmail.com>
Date: Fri, 18 Oct 2019 22:56:34 +0200
Subject: [PATCH] Update FAQ section on large files (Bug#37818)

* doc/misc/efaq.texi (Problems with very large files): Extend section
and remove information about ancient versions of Emacs.
---
 doc/misc/efaq.texi | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/doc/misc/efaq.texi b/doc/misc/efaq.texi
index 0f2cebe6c3..38781760d3 100644
--- a/doc/misc/efaq.texi
+++ b/doc/misc/efaq.texi
@@ -2923,20 +2923,27 @@ Bugs and problems
 @end menu
 
 @node Problems with very large files
-@section Does Emacs have problems with files larger than 8 megabytes?
+@section Does Emacs have problems with large files?
 @cindex Very large files, opening
 @cindex Large files, opening
 @cindex Opening very large files
 @cindex Maximum file size
 @cindex Files, maximum size
 
-Old versions (i.e., anything before 19.29) of Emacs had problems editing
-files larger than 8 megabytes.  In versions 19.29 and later, the maximum
-buffer size is at least @math{2^{27}-1}, or 134,217,727 bytes, or 132 MBytes.
-The maximum buffer size on 32-bit machines increased to 256 MBytes in
-Emacs 22, and again to 512 MBytes in Emacs 23.2.
+Emacs has an inherent fixed limitation on the size of buffers.  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.
 
-Emacs compiled on a 64-bit machine can handle much larger buffers.
+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.
 
 @node ^M in the shell buffer
 @section How do I get rid of @samp{^M} or echoed commands in my shell buffer?
-- 
2.23.0