Re: Patch to "generalize" setting section start addresses via command line - TAKE 2

[Thomas de Lellis <tdel at windriver dot com>]

Nick Clifton wrote:

>   I think it should be relatively easy for you to change your patch so
> that the code in parse_args() actually parses the entirety of your new
> switch and then calls lang_section_start() directly.  If you would
> like to do that and then resubmit the patch I will be happy to review
> it again.

Hi Nick,


thanks for the tips.

Here's a new and improved (and simpler) patch...


Tom
TAKE 2

Patch to "generalize" setting of section start addresses
via the command line.

The GNU ld linker only allows -T with the
.text, .data, and .bss sections via the command line
options:

-Ttext org
-Tdata org
-Tbss org

The gnu linker is also quirky in that -T is used for both
section start addresses and using external linker command files.
If you use -T with ANY other name besides text/data/bss, it
assumes it's looking for an external linker command script.

We needed a simple way to set start adresses of other sections
from the command line, but, we also use -T for external linker
scripts so wanted to preserve all the present ld behavior. We
ended up adding a new command line option:

--section-start sectionname=org

sectionname can be any section instead of just .text/.data/.bss
and you must include all the characters (.) in your section
names... (the syntax is like that of -defsym)

--section-start .mysection=0x20000

:
:

-Ttext 0x1234 translates to --section-start .text=0x1234

=======================================================================
ld/ChangeLog
2000-05-22  Thomas de Lellis  <tdel@windriver.com>

        * ld.1: added documentation for new command line option
        --section-start sectionname=sectionorg
        This is a generic version of -Ttext etc. which accepts
        any section name as a parameter instead of just
        text/data/bss.
        * ld.texinfo: more docs.
        * ldlexsup: (parse_args): recognize new command line option.
        
=======================================================================
*** ../ld/ld.1	Fri May 19 11:02:12 2000
--- ld.1	Mon May 22 13:35:00 2000
*************** ld \- the GNU linker
*** 39,45 ****
  .br
  .RB "[\|" "\-defsym\ "\c
  .I symbol\c
! \& = \c
  .I expression\c
  \&\|]
  .RB "[\|" \-\-demangle "\|]"
--- 39,45 ----
  .br
  .RB "[\|" "\-defsym\ "\c
  .I symbol\c
! \&=\c
  .I expression\c
  \&\|]
  .RB "[\|" \-\-demangle "\|]"
*************** ld \- the GNU linker
*** 122,127 ****
--- 122,132 ----
  .RB "[\|" "\-T\ "\c
  .I commandfile\c
  \&\|]  
+ .RB "[\|" "\-\-section\-start\ "\c
+ .I sectionname\c
+ \&=\c
+ .I sectionorg\c
+ \&\|]
  .RB "[\|" "\-Ttext\ "\c
  .I textorg\c
  \&\|] 
*************** The exceptions\(em\&which may meaningful
*** 253,260 ****
  .B \-format\c
  \&), \c
  .B \-defsym\c
! \&,
! \c
  .B \-L\c
  \&, \c
  .B \-l\c
--- 258,266 ----
  .B \-format\c
  \&), \c
  .B \-defsym\c
! \&, \c
! .B \-\-section\-start\c
! \&, \c
  .B \-L\c
  \&, \c
  .B \-l\c
*************** specified (\c
*** 454,460 ****
  \& has the same effect.
  
  .TP
! .BI "-defsym " "symbol" "\fR = \fP" expression
  Create a global symbol in the output file, containing the absolute
  address given by \c
  .I expression\c
--- 460,466 ----
  \& has the same effect.
  
  .TP
! .BI "-defsym " "symbol" "\fR=\fP" expression
  Create a global symbol in the output file, containing the absolute
  address given by \c
  .I expression\c
*************** relocations one output section will cont
*** 888,893 ****
--- 894,913 ----
  Similar to
  .B \-split\-by\-reloc
  but creates a new output section for each input file.
+ 
+ .TP
+ .BI "--section-start " "sectionname" "\fR=\fP"org
+ Locate a section in the output file at the absolute
+ address given by \c
+ .I org\c
+ \&.  \c
+ \c
+ .I org\c
+ \& must be a hexadecimal integer.
+ You may use this option as many
+ times as necessary to locate multiple sections in the command
+ line.  If you need more elaborate expressions, consider
+ using the linker command language from a script.
  
  .TP
  .BI "\-Tbss " "org"\c
=======================================================================
*** ../ld/ld.texinfo	Fri May 19 11:02:15 2000
--- ld.texinfo	Mon May 22 13:39:11 2000
*************** full debugging information by over 30 pe
*** 1143,1148 ****
--- 1143,1160 ----
  trouble).  The @samp{--traditional-format} switch tells @code{ld} to not
  combine duplicate entries.
  
+ @kindex --section-start @var{sectionname}=@var{org}
+ @item --section-start @var{sectionname}=@var{org}
+ Locate a section in the output file at the absolute
+ address given by @var{org}.  You may use this option as many
+ times as necessary to locate multiple sections in the command
+ line.
+ @var{org} must be a single hexadecimal integer;
+ for compatibility with other linkers, you may omit the leading
+ @samp{0x} usually associated with hexadecimal values.  @emph{Note:} there
+ should be no white space between @var{sectionname}, the equals
+ sign (``@key{=}''), and @var{org}.
+ 
  @kindex -Tbss @var{org}
  @kindex -Tdata @var{org}
  @kindex -Ttext @var{org}
=======================================================================
*** ../ld/lexsup.c	Fri May 19 11:02:20 2000
--- lexsup.c	Mon May 22 13:43:59 2000
*************** int parsing_defsym = 0;
*** 123,128 ****
--- 123,129 ----
  #define OPTION_NO_UNDEFINED		(OPTION_MPC860C0 + 1)
  #define OPTION_INIT                     (OPTION_NO_UNDEFINED + 1)
  #define OPTION_FINI                     (OPTION_INIT + 1)
+ #define OPTION_SECTION_START		(OPTION_FINI + 1)
  
  /* The long options.  This structure is used for both the option
     parsing and the help text.  */
*************** static const struct ld_option ld_options
*** 336,341 ****
--- 337,344 ----
        '\0', N_("SYMBOL"), N_("Do task level linking"), TWO_DASHES },
    { {"traditional-format", no_argument, NULL, OPTION_TRADITIONAL_FORMAT},
        '\0', NULL, N_("Use same format as native linker"), TWO_DASHES },
+   { {"section-start", required_argument, NULL, OPTION_SECTION_START},
+       '\0', N_("SYMBOL=EXPRESSION"), N_("Set address of named section"), TWO_DASHES },
    { {"Tbss", required_argument, NULL, OPTION_TBSS},
        '\0', N_("ADDRESS"), N_("Set address of .bss section"), ONE_DASH },
    { {"Tdata", required_argument, NULL, OPTION_TDATA},
*************** parse_args (argc, argv)
*** 840,845 ****
--- 843,877 ----
  	  ldfile_open_command_file (optarg);
  	  parser_input = input_script;
  	  yyparse ();
+ 	  break;
+ 	case OPTION_SECTION_START:
+ 	  {
+ 	    char *optarg2;
+ 
+ 	    /* Check for <something>=<somthing>...  */
+ 	    optarg2 = strchr (optarg, '=');
+ 	    if (optarg2 == NULL)
+ 	      {
+ 		fprintf (stderr,
+ 			 _("%s: Invalid argument to option \"--section-start\"\n"),
+ 			 program_name);
+ 		xexit (1);
+ 	      }
+ 
+ 	    *optarg2++ = '\0';
+ 
+ 	    /* So far so good.  Are all the args present?  */
+ 	    if ((*optarg == '\0') || (*optarg2 == '\0'))
+ 	      {
+ 		fprintf (stderr,
+ 			 _("%s: Missing argument(s) to option \"--section-start\"\n"),
+ 			 program_name);
+ 		xexit (1);
+ 	      }
+ 
+ 	    /* Then set it...  */
+ 	    set_section_start (optarg, optarg2);
+ 	  }
  	  break;
  	case OPTION_TBSS:
  	  set_section_start (".bss", optarg);
=======================================================================