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authorKarl Berry <karl@freefriends.org>2021-07-18 17:16:29 +0000
committerKarl Berry <karl@freefriends.org>2021-07-18 17:16:29 +0000
commit78591567fc12bcecdf39f8d632d39c12568401ea (patch)
treebb339f362e3a36d653efa2f7fbd7e219b12abde7 /Build/source/texk/web2c/doc/web2c.texi
parent24ff0d4c91e4e1d9c2d149465d25d78e24825325 (diff)
checking fmt sharability across architectures
git-svn-id: svn://tug.org/texlive/trunk@59973 c570f23f-e606-0410-a88d-b1316a301751
Diffstat (limited to 'Build/source/texk/web2c/doc/web2c.texi')
-rw-r--r--Build/source/texk/web2c/doc/web2c.texi51
1 files changed, 32 insertions, 19 deletions
diff --git a/Build/source/texk/web2c/doc/web2c.texi b/Build/source/texk/web2c/doc/web2c.texi
index 447c19f3e62..46ef2741455 100644
--- a/Build/source/texk/web2c/doc/web2c.texi
+++ b/Build/source/texk/web2c/doc/web2c.texi
@@ -12,7 +12,7 @@ The latest version is available from ftp://ftp.tug.org/tex/texinfo.tex.}
@end tex
@set version 2021
-@set month-year May 2021
+@set month-year July 2021
@c Define new indices for commands in auxiliary files, filenames, and options.
@defcodeindex cm
@@ -789,24 +789,34 @@ will be used.
@cindex machine dependencies
@cindex architecture dependencies
@cindex dependencies, hardware
-@opindex --disable-dump-share configure @r{option}
-By default, memory dump files are generally sharable between
-architectures of different types; specifically, on machines of different
-endianness (@pxref{Byte order,,,libc,GNU C Library}). (This is a
+@cindex 32-bit architecture
+@cindex 64-bit architecture
+@cindex @code{long} data type, size of
+By default, memory dump files are sharable between architectures of
+different types; specifically, on machines of different endianness
+(@pxref{Byte order,,, libc, GNU C Library}) and with different word
+sizes (4-byte @code{long} vs.@: 8-byte @code{long}). This is a
feature of the Web2c implementation, and is not true of all @TeX{}
-implementations.) If you specify @samp{--disable-dump-share} to
-@code{configure}, however, memory dumps will be endian-dependent.
+implementations.
+
+@pindex tl-check-fmtshare
+The script @code{tl-check-fmtshare} in the @TeX{} Live source tree
+(@file{Master/tlpkg/bin}) provides a relatively easy way to test that
+a @file{.fmt} built on the local host can be loaded by a @TeX{} engine
+built on some remote host.
@cindex byte swapping
@cindex swapping bytes
-The reason to do this is speed. To achieve endian-independence, the
-reading of memory dumps on LittleEndian architectures, such as PC's and
-DEC architectures, is somewhat slowed (all the multibyte values have to
-be swapped). Usually, this is not noticeable, and the advantage of
-being able to share memory dumps across all platforms at a site far
-outweighs the speed loss. But if you're installing Web2c for use on
-LittleEndian machines only, perhaps on a PC being used only by you, you
-may wish to get maximum speed.
+@opindex --disable-dump-share configure @r{option}
+If you specify @samp{--disable-dump-share} to @code{configure},
+however, memory dumps will be endian-dependent. The reason to do this
+is speed. To achieve endian-independence, the reading of memory dumps
+on LittleEndian architectures, such as PC's and DEC architectures, is
+somewhat slowed (all the multibyte values have to be swapped).
+Usually, this is not noticeable, and the advantage of being able to
+share memory dumps across all platforms at a site far outweighs the
+speed loss. But if you're trying to squeeze out every possible bit of
+performance, you may wish to do this.
@cindex floating-point values
@cindex glue ratio representations
@@ -814,8 +824,8 @@ may wish to get maximum speed.
@file{.fmt} files cannot be guaranteed to work. Floating-point values
are always written in native format, and hence will generally not be
readable across platforms. Fortunately, @TeX{} uses floating point
-only to represent glue ratios, and all common formats (plain,
-@LaTeX{}, AMS@TeX{}, @dots{}) do not do any glue setting at
+only to represent glue ratios, and none of the common formats (plain,
+@LaTeX{}, AMS@TeX{}, @dots{}) do any glue setting at
@file{.fmt}-creation time. Metafont does not use floating point in
any dumped value at all.
@@ -823,8 +833,8 @@ any dumped value at all.
@cindex time and date, in memory dumps
@cindex memory dumps, contain date and time
Incidentally, different memory dump files will never compare equal
-byte-for-byte, because the program always dumps the current date and
-time. So don't be alarmed by just a few bytes difference.
+byte-for-byte, because the programs dump the current date and time. So
+don't be alarmed by a few bytes difference.
@cindex Harbison, Samuel P.
@cindex Steele Jr., Guy L.
@@ -855,6 +865,9 @@ main ()
@}
@end example
+You can add @code{printf("long %d\n", sizeof(long));} to see the size
+of the @code{long} data type.
+
@node Editor invocation
@section Editor invocation