Port to modern GCC and pdumper on MS-DOS

* config.bat (mvOk): Protoize.
(djgppOk): Include sys/version.h for _DJGPP_MINOR.

* lisp/loadup.el: If system-type is ms-dos, dump bootstrap-emacs
as b-emacs.dmp.

* msdos/INSTALL: Document new versions of tools that have been
verified successfully to compile Emacs.

* msdos/emacs.djl: New linker script that arranges to link
symbols in `.subrs' in a contiguous part of data, as the DJGPP
runtime appears to treat any non-data and non-text section as
allocatable.

* msdos/mainmake.v2 (install): Install emacs.dmp alongside
emacs.exe.

* msdos/sed1v2.inp (CFLAGS): Define to -O2 -g3.
(LDFLAGS): Provide the said linker script.
(HAVE_PDUMPER): Define to yes.
(UNEXEC_OBJ, PAXCTL_dumped, PAXCTL_notdumped): Delete.
(DUMPING): Set to pdumper.
(MAKE_PDUMPER_FINGERPRINT): Don't erase this variable.
Don't stubify or set minstack.  Remove native-comp specific
directives.  Don't remove temacs prior to copying and replace
`pdmp' extension with DOS-conformant `dmp'.

* msdos/sed2v2.inp (HAVE_UNEXEC): Remove definition.
(HAVE_PDUMPER): Define to 1.

* msdos/sed6.inp (top_srcdir): Define appropriately.

* msdos/sedlibmk.inp (HAVE_BLKCNT_T): Define to 1.

* src/emacs.c (load_pdump) [MSDOS]: Use `dmp' suffix.

* src/pdumper.c (Fdump_emacs_portable) [MSDOS]: Replace ".pdmp"
suffixes with ".dmp".

config.bat

@@ -94,7 +94,7 @@ Goto End
 :mvOk
 rm -f junk.2
 Echo Checking whether 'gcc' is available...
-echo main(){} >junk.c
+echo int main(void){} >junk.c
 gcc -c junk.c
 if exist junk.o goto gccOk
 Echo To configure 'Emacs' you need to have 'gcc'!
@@ -107,7 +107,8 @@ If Not "%DJGPP%" == "" goto djgppOk
 Echo To compile 'Emacs' under MS-DOS you MUST have DJGPP installed!
 Goto End
 :djgppOk
-echo int main()           >junk.c
+echo #include "sys/version.h" >junk.c
+echo int main()          >>junk.c
 echo #ifdef __DJGPP__    >>junk.c
 echo {return (__DJGPP__)*10 + (__DJGPP_MINOR__);} >>junk.c
 echo #else               >>junk.c

lisp/loadup.el

@@ -600,7 +600,10 @@ directory got moved.  This is set to be a pair in the form of:
               (error nil))))))
   (if dump-mode
       (let ((output (cond ((equal dump-mode "pdump") "emacs.pdmp")
-                          ((equal dump-mode "pbootstrap") "bootstrap-emacs.pdmp")
+                          ((equal dump-mode "pbootstrap")
+                           (if (eq system-type 'ms-dos)
+                               "b-emacs.pdmp"
+                             "bootstrap-emacs.pdmp"))
                           (t (error "Unrecognized dump mode %s" dump-mode)))))
         (when (and (featurep 'native-compile)
                    (equal dump-mode "pdump"))

msdos/INSTALL

@@ -19,14 +19,9 @@ the necessary utilities; search for "MS-DOS".  The configuration step
 (see below) will test for these utilities and will refuse to continue
 if any of them isn't found.
 
-You should carefully choose the version of GCC you use to build Emacs,
+Binutils 2.35.1 with GCC 14.2.0 have been verified to be capable of
-because recent versions of GCC don't support building Emacs very well.
+compiling the MS-DOS port of Emacs, and GDB 8.0.1, to be capable of
-The main issue is the debug info: the DJGPP build of Emacs must use
+debugging Emacs executables produced by this configuration.
-the COFF debug info.  GCC support for COFF debug info was steadily
-deteriorating since GCC 5, and GCC 8.1 officially stopped supporting
-the -gcoff switch, which the Emacs build process needs.  We recommend
-using GCC 3.4.X and Binutils 2.26; GDB 7.2 is capable to debug an
-Emacs binary built by this combination.
 
 Bootstrapping Emacs or recompiling Lisp files in the `lisp'
 subdirectory using the various targets in the lisp/Makefile file

msdos/emacs.djl

@@ -0,0 +1,95 @@
+/* Modified version of the default DJGPP linker script for GNU -*- c -*-
+   Emacs.  */
+
+/* Default linker script, for normal executables */
+/* Copyright (C) 2014 Free Software Foundation, Inc.
+   Copying and distribution of this script, with or without modification,
+   are permitted in any medium without royalty provided the copyright
+   notice and this notice are preserved.  */
+OUTPUT_FORMAT("coff-go32-exe")
+ENTRY (start)
+SECTIONS
+{
+  .text  0x1000+SIZEOF_HEADERS : {
+    *(.text)
+    *(.text.*)
+    *(.gnu.linkonce.t*)
+    *(.const*)
+    *(.ro*)
+    *(.gnu.linkonce.r*)
+    etext  =  . ; PROVIDE(_etext = .) ;
+    . = ALIGN(0x200);
+  }
+  .data  ALIGN(0x200) : {
+    djgpp_first_ctor = . ;
+    *(SORT(.ctors.*))
+    *(.ctor)
+    *(.ctors)
+    djgpp_last_ctor = . ;
+    djgpp_first_dtor = . ;
+    *(SORT(.dtors.*))
+    *(.dtor)
+    *(.dtors)
+    djgpp_last_dtor = . ;
+    __environ = . ;
+    PROVIDE(_environ = .) ;
+    LONG(0) ;
+    *(.data)
+    *(.data.*)
+    *(.subrs)
+    *(.subrs.*)
+    /* Ugly workaround to prevent entire .bss to have attribute CONTENT */
+    /* for C++ executables. */
+    *( .bss.*)
+    *(.gcc_exc*)
+    ___EH_FRAME_BEGIN__ = . ;
+    *(.eh_fram*)
+    ___EH_FRAME_END__ = . ;
+    LONG(0) ;
+    *(.gnu.linkonce.d*)
+    edata  =  . ; PROVIDE(_edata = .) ;
+    . = ALIGN(0x200);
+  }
+  .bss  SIZEOF(.data) + ADDR(.data) :
+  {
+    *(.bss .gnu.linkonce.b.*)
+    *(COMMON)
+     end = . ; PROVIDE(_end = .) ;
+     . = ALIGN(0x200);
+  }
+  /* Discard LTO sections.  */
+  /DISCARD/ : { *(gnu.lto_*) }
+  /* Stabs debugging sections.  */
+  .stab 0 : { *(.stab) }
+  .stabstr 0 : { *(.stabstr) }
+  /* DWARF debug sections.
+     Symbols in the DWARF debugging sections are relative to the beginning
+     of the section so we begin them at 0.  */
+  /* DWARF 1 */
+  .debug          0 : { *(.debug) }
+  .line           0 : { *(.line) }
+  /* GNU DWARF 1 extensions */
+  .debug_srcinfo  0 : { *(.debug_srcinfo) }
+  .debug_sfnames  0 : { *(.debug_sfnames) }
+  /* DWARF 1.1 and DWARF 2 */
+  .debug_aranges  0 : { *(.debug_aranges) }
+  .debug_pubnames 0 : { *(.debug_pubnames) }
+  /* DWARF 2 */
+  .debug_info     0 : { *(.debug_info .gnu.linkonce.wi.*) }
+  .debug_abbrev   0 : { *(.debug_abbrev) }
+  .debug_line     0 : { *(.debug_line .debug_line.* .debug_line_end ) }
+  .debug_frame    0 : { *(.debug_frame) }
+  .debug_str      0 : { *(.debug_str) }
+  .debug_loc      0 : { *(.debug_loc) }
+  .debug_macinfo  0 : { *(.debug_macinfo) }
+  /* SGI/MIPS DWARF 2 extensions */
+  .debug_weaknames 0 : { *(.debug_weaknames) }
+  .debug_funcnames 0 : { *(.debug_funcnames) }
+  .debug_typenames 0 : { *(.debug_typenames) }
+  .debug_varnames  0 : { *(.debug_varnames) }
+  /* DWARF 3 */
+  .debug_pubtypes 0 : { *(.debug_pubtypes) }
+  .debug_ranges   0 : { *(.debug_ranges) }
+  /* DWARF Extension.  */
+  .debug_macro    0 : { *(.debug_macro) }
+}

msdos/mainmake.v2

@@ -136,6 +136,7 @@ install: all
 	cd ..
 	cd src
 	mv -f emacs.exe ../bin/
+	mv -f emacs.dmp ../bin/
 	cd ..
 	djecho -s "(if (fboundp 'normal-top-level-add-subdirs-to-load-path)" \
 	          "    (normal-top-level-add-subdirs-to-load-path))" \

msdos/sed1v2.inp

@@ -22,11 +22,11 @@ s/\.h\.in/.h-in/
 /^srcdir *=/s/@[^@\n]*@/./
 /^top_srcdir *=/s/@[^@\n]*@/../
 /^CC *=/s/@[^@\n]*@/gcc -std=gnu99/
-/^CFLAGS *=/s/@[^@\n]*@/-O2 -gcoff/
+/^CFLAGS *=/s/@[^@\n]*@/-O2 -g3/
 /^ALL_CFLAGS *=/s/@[^@\n]*@//g
 /^ALL_CFLAGS *=/s/ -I\.//g
 /^CPPFLAGS *=/s|@[^@\n]*@|-I../msdos|
-/^LDFLAGS *=/s/@[^@\n]*@//
+/^LDFLAGS *=/s/@[^@\n]*@/-T ..\/msdos\/emacs.djl/
 /^LIBOBJS *=/s/@[^@\n]*@//
 /^C_SWITCH_MACHINE *=/s/@C_SWITCH_MACHINE@//
 /^C_SWITCH_SYSTEM *=/s/@C_SWITCH_SYSTEM@//
@@ -60,7 +60,7 @@ s/ *@WEBP_LIBS@//
 /^JPEG_CFLAGS *=/s/@JPEG_CFLAGS@//
 /^TIFF_CFLAGS *=/s/@TIFF_CFLAGS@//
 /^HAVE_NATIVE_COMP *=/s/@HAVE_NATIVE_COMP@/no/
-/^HAVE_PDUMPER *=/s/@HAVE_PDUMPER@/no/
+/^HAVE_PDUMPER *=/s/@HAVE_PDUMPER@/yes/
 /^HAVE_BE_APP *=/s/@HAVE_BE_APP@/no/
 /^CHECK_STRUCTS *=/s/@CHECK_STRUCTS@//
 /^RUN_TEMACS \=/s/temacs/temacs.exe/
@@ -166,7 +166,6 @@ s/ *@WEBP_LIBS@//
 /^GMALLOC_OBJ *=/s/@GMALLOC_OBJ@/gmalloc.o/
 /^VMLIMIT_OBJ *=/s/@VMLIMIT_OBJ@/vm-limit.o/
 /^RALLOC_OBJ *=/s/@RALLOC_OBJ@/ralloc.o/
-/^UNEXEC_OBJ *=/s/@UNEXEC_OBJ@/unexcoff.o/
 /^BUILD_DETAILS *=/s/@BUILD_DETAILS@//
 /^CANNOT_DUMP *=/s/@CANNOT_DUMP@/no/
 /^W32_OBJ *=/s/@W32_OBJ@//
@@ -194,9 +193,7 @@ s/ *@WEBP_LIBS@//
 /^[Aa][Mm]_/s/@AM_V@/$(V)/
 /^[Aa][Mm]_/s/@AM_DEFAULT_V@/$(AM_DEFAULT_VERBOSITY)/
 /^AUTO_DEPEND *=/s/@AUTO_DEPEND@/yes/
-/^PAXCTL_dumped *=/s/=.*$/=/
+/^DUMPING *=/s/@DUMPING@/pdumper/
-/^PAXCTL_notdumped *=/s/=.*$/=/
-/^DUMPING *=/s/@DUMPING@/unexec/
 /^ANDROID_OBJ *=/s/@ANDROID_OBJ@//
 /^ANDROID_LIBS *=/s/@ANDROID_LIBS@//
 /^ANDROID_LDFLAGS *=/s/@ANDROID_LDFLAGS@//
@@ -205,8 +202,6 @@ s/ *@WEBP_LIBS@//
 /^SQLITE3_CFLAGS *=/s/@SQLITE3_CFLAGS@//
 /^LIBSELINUX_CFLAGS *=/s/@LIBSELINUX_CFLAGS@//
 /^XCONFIGURE *=/s/@XCONFIGURE@//
-/^[ \t]*MAKE_PDUMPER_FINGERPRINT = *$/c\
-MAKE_PDUMPER_FINGERPRINT =
 # While this variable is named abs_top_builddir, the distinction is
 # only relevant when Emacs is undergoing cross-compilation.
 /^abs_top_builddir =*/s/@abs_top_builddir@/../
@@ -237,14 +232,8 @@ lisp.mk: $(lispsource)/loadup.el\
 /^	 *ln /s/ln /cp /
 /^	fi/d
 /ifeq (\$(HAVE_NATIVE_COMP):\$(NATIVE_DISABLED),yes:)/,/endif/d
-/^	 *\$(RUN_TEMACS) /i\
-	stubedit temacs.exe minstack=1024k
-/^	 *LC_ALL=C \$(RUN_TEMACS)/i\
-	stubedit temacs.exe minstack=1024k
 /^	 *LC_ALL=C.*\$(RUN_TEMACS)/s/LC_ALL=C/set &;/
-/-batch .* -l loadup/a\
+/^	ANCIENT=yes \$(MAKE) -C ..\/lisp compile-first EMACS="\$(bootstrap_exe)"/d
-	stubify emacs\
-	stubedit emacs.exe minstack=3072k
 s/ @true *$/ @rem/
 s/^	[^ 	]*move-if-change /	update /
 /^	[^ 	]*echo[ 	][ 	]*timestamp/s/echo /djecho /
@@ -271,6 +260,8 @@ s/echo.*buildobj.lst/dj&/
   /^	 *\$(AM_V_GEN)for /,/mv \$@.tmp \$@/c\
 	djecho "$(ALLOBJS)" | sed -e 's/^ */"/' -e 's/ *$$/"/' -e 's/  */", "/g' >>$@
 }
+/^	.*\$(MAKE_PDUMPER_FINGERPRINT) \$@\.tmp/s/\.tmp//
+/^	rm -f \$@ && cp -f temacs\$(EXEEXT) \$@/s/rm -f \$@ && //
 # Remove or replace dependencies we cannot have
 /^\.PRECIOUS: /s!\.\./config.status !!
 /^\.\.\/config.status: /,/^	/d
@@ -293,3 +284,4 @@ s| -I\. -I\$(srcdir)| -I.|
 /\$(CC) -o \$@.tmp/s/\$@.tmp/\$@/
 /mv \$@.tmp \$@/d
 /^top_builddir =*/s/@top_builddir@/../
+s/\.pdmp/\.dmp/

msdos/sed2v2.inp

@@ -37,7 +37,6 @@
 /^#undef HAVE_STRUCT_UTIMBUF *$/s/^.*$/#define HAVE_STRUCT_UTIMBUF 1/
 /^#undef LOCALTIME_CACHE *$/s/^.*$/#define LOCALTIME_CACHE 1/
 /^#undef HAVE_TZSET *$/s/^.*$/#define HAVE_TZSET 1/
-/^#undef HAVE_UNEXEC *$/s/^.*$/#define HAVE_UNEXEC 1/
 /^#undef HAVE_RINT *$/s/^.*$/#define HAVE_RINT 1/
 /^#undef HAVE_C99_STRTOLD *$/s/^.*$/#define HAVE_C99_STRTOLD 1/
 /^#undef HAVE_DIFFTIME *$/s/^.*$/#define HAVE_DIFFTIME 1/
@@ -138,6 +137,7 @@ s/^#undef HAVE_DECL_PUTCHAR_UNLOCKED *$/#define HAVE_DECL_PUTCHAR_UNLOCKED 0/
 s/^#undef HAVE_DECL_PUTC_UNLOCKED *$/#define HAVE_DECL_PUTC_UNLOCKED 0/
 s/^#undef HAVE_DECL_STRTOLL *$/#define HAVE_DECL_STRTOLL 1/
 s/^#undef HAVE_DECL_STRTOIMAX *$/#define HAVE_DECL_STRTOIMAX 1/
+s/^#undef HAVE_PDUMPER *$/#define HAVE_PDUMPER 1/
 s/^#undef HAVE_STRTOLL *$/#define HAVE_STRTOLL 1/
 s/^#undef HAVE_STRTOULL *$/#define HAVE_STRTOULL 1/
 /^#undef HAVE_STRUCT_DIRENT_D_TYPE *$/c\

msdos/sed6.inp

@@ -17,6 +17,7 @@
 #
 # ----------------------------------------------------------------------
 /^srcdir *=/s/@[^@\n]*@/./
+/^top_srcdir *=/s/@[^@\n]*@/..\/../
 /^VPATH *=/s/@[^@\n]*@/./
 /^MAKEINFO *=/s/@[^@\n]*@/makeinfo/
 /^AM_DEFAULT_VERBOSITY *=/s/@AM_DEFAULT_VERBOSITY@/1/

msdos/sedlibmk.inp

@@ -208,6 +208,7 @@ s/@PACKAGE@/emacs/
 #
 # Edit the HAVE_foo variables
 /^HAVE_ATOLL *=/s/@HAVE_ATOLL@/0/
+/^HAVE_BLKCNT_T *=/s/@HAVE_BLKCNT_T@/1/
 /^HAVE_CHOWN *=/s/@HAVE_CHOWN@/1/
 /^HAVE_CLOSEDIR *=/s/@HAVE_CLOSEDIR@/1/
 /^HAVE_DECL_GETPAGESIZE *=/s/@HAVE_DECL_GETPAGESIZE@/1/

src/emacs.c

@@ -885,7 +885,11 @@ load_pdump (int argc, char **argv, char *dump_file)
   return argv[0];
 #else
 
+#ifdef MSDOS
+  const char *const suffix = ".dmp";
+#else /* !MSDOS */
   const char *const suffix = ".pdmp";
+#endif /* !MSDOS */
   int result;
   char *emacs_executable = argv[0];
   ptrdiff_t hexbuf_size;

src/lisp.h

@@ -3399,9 +3399,10 @@ CHECK_SUBR (Lisp_Object x)
    for more efficient dump loading.  */
 #ifdef DARWIN_OS
 # define SUBR_SECTION_ATTRIBUTE ATTRIBUTE_SECTION ("__DATA,subrs")
-#else
+#else /* !DARWIN_OS */
 # define SUBR_SECTION_ATTRIBUTE ATTRIBUTE_SECTION (".subrs")
-#endif
+#endif /* !DARWIN_OS */
+
 
 /* Define a built-in function for calling from Lisp.
  `lname' should be the name to give the function in Lisp,

src/pdumper.c

@@ -4243,8 +4243,24 @@ types.  */)
   ctx->old_process_environment = Vprocess_environment;
   Vprocess_environment = Qnil;
 
-  ctx->fd = emacs_open (SSDATA (filename),
+  {
-                        O_RDWR | O_TRUNC | O_CREAT, 0666);
+    USE_SAFE_ALLOCA;
+
+    char *filename_1;
+    SAFE_ALLOCA_STRING (filename_1, filename);
+#ifdef MSDOS
+    /* Rewrite references to .pdmp to refer to .dmp files on DOS.  */
+    size_t len = strlen (filename_1);
+    if (len >= 5
+	&& !strcmp (filename_1 + len - 5, ".pdmp"))
+      {
+	strcpy (filename_1 + len - 5, ".dmp");
+	filename = DECODE_FILE (build_unibyte_string (filename_1));
+      }
+#endif /* !MSDOS */
+    ctx->fd = emacs_open (filename_1, O_RDWR | O_TRUNC | O_CREAT, 0666);
+    SAFE_FREE ();
+  }
   if (ctx->fd < 0)
     report_file_error ("Opening dump output", filename);
   static_assert (sizeof (ctx->header.magic) == sizeof (dump_magic));