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diff docs/manual/x942.html @ 517:1faf14de9d04
Update manual to correctly reflect forwardrefmax behaviour
Add a note to autobranchlength referencing forwardrefmax and also not that
forwardrefmax is enabled by default.
| author | William Astle <lost@l-w.ca> |
|---|---|
| date | Tue, 13 Apr 2021 15:38:12 -0600 |
| parents | |
| children | 543b5d1341d2 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/docs/manual/x942.html Tue Apr 13 15:38:12 2021 -0600 @@ -0,0 +1,339 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd"> +<HTML +><HEAD +><TITLE +>Linking Scripts</TITLE +><META +NAME="GENERATOR" +CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK +REL="HOME" +TITLE="LW Tool Chain" +HREF="index.html"><LINK +REL="UP" +TITLE="LWLINK" +HREF="c828.html"><LINK +REL="PREVIOUS" +TITLE="Linker Operation" +HREF="x928.html"><LINK +REL="NEXT" +TITLE="Format Specific Linking Notes" +HREF="x1008.html"></HEAD +><BODY +CLASS="SECTION" +BGCOLOR="#FFFFFF" +TEXT="#000000" +LINK="#0000FF" +VLINK="#840084" +ALINK="#0000FF" +><DIV +CLASS="NAVHEADER" +><TABLE +SUMMARY="Header navigation table" +WIDTH="100%" +BORDER="0" +CELLPADDING="0" +CELLSPACING="0" +><TR +><TH +COLSPAN="3" +ALIGN="center" +>LW Tool Chain</TH +></TR +><TR +><TD +WIDTH="10%" +ALIGN="left" +VALIGN="bottom" +><A +HREF="x928.html" +ACCESSKEY="P" +>Prev</A +></TD +><TD +WIDTH="80%" +ALIGN="center" +VALIGN="bottom" +>Chapter 4. LWLINK</TD +><TD +WIDTH="10%" +ALIGN="right" +VALIGN="bottom" +><A +HREF="x1008.html" +ACCESSKEY="N" +>Next</A +></TD +></TR +></TABLE +><HR +ALIGN="LEFT" +WIDTH="100%"></DIV +><DIV +CLASS="SECTION" +><H1 +CLASS="SECTION" +><A +NAME="AEN942" +>4.3. Linking Scripts</A +></H1 +><P +>A linker script is used to instruct the linker about how to assemble the +various sections into a completed binary. It consists of a series of +directives which are considered in the order they are encountered.</P +><P +>The sections will appear in the resulting binary in the order they are +specified in the script file. If a referenced section is not found, the linker will behave as though the +section did exist but had a zero size, no relocations, and no exports. +A section should only be referenced once. Any subsequent references will have +an undefined effect.</P +><P +>All numbers are in linking scripts are specified in hexadecimal. All directives +are case sensitive although the hexadecimal numbers are not.</P +><P +>A section name can be specified as a "*", then any section not +already matched by the script will be matched. The "*" can be followed +by a comma and a flag to narrow the section down slightly, also. +If the flag is "!bss", then any section that is not flagged as a bss section +will be matched. If the flag is "bss", then any section that is flagged as +bss will be matched.</P +><P +>The following directives are understood in a linker script.</P +><P +></P +><DIV +CLASS="VARIABLELIST" +><DL +><DT +>sectopt <CODE +CLASS="PARAMETER" +>section</CODE +> padafter <CODE +CLASS="PARAMETER" +>byte,...</CODE +></DT +><DD +><P +> This will cause the linker to append the specified list of byte values +(specified in hexadecimal separated by commas) to the end of the named +section. This is done once all instances of the specified section are +collected together. This has no effect if the specified section does not +appear anywhere in any of the objects specified for linking. </P +><P +> If code depends on the presence of this padding somewhere, it is sufficient +to include an empty section of the specified name in the object that depends +on it. </P +></DD +><DT +>define basesympat <CODE +CLASS="PARAMETER" +>string</CODE +></DT +><DD +><P +> This causes the linker to define a symbol for the ultimate base address of +each section using the pattern specified by <CODE +CLASS="PARAMETER" +>string</CODE +>. +In the string, %s can appear exactly once and will be replaced with the +section name. The base address is calculated after all instances of each +section have been collapsed together. </P +><P +> It should be noted that if none of the objects to be linked contains a +particular section name, there will be no base symbol defined for it, even +if it is listed explicitly in the link script. If code depends on the +presence of these symbols, it is sufficient to include an empty section of +the specified name in the object that depends on it. </P +><P +> If the pattern resolves to the same string for multiple +sections, the results are undefined. </P +></DD +><DT +>define lensympat <CODE +CLASS="PARAMETER" +>string</CODE +></DT +><DD +><P +> This causes the linker to define a symbol for the ultimate length of each +section using the pattern specified by <CODE +CLASS="PARAMETER" +>string</CODE +>. In +the string, %s can appear exactly once and will be replaced with the section +name. The length is calculated after all instances of a section have been +collapsed together. </P +><P +> It should be noted that if none of the objects to be linked contains a +particular section name, there will be no length symbol defined for it, even +if it is listed explicitly in the link script. If code depends on the +presence of these symbols, it is sufficient to include an empty section of +the specified name in the object that depends on it. </P +><P +>If the pattern resolves to the same string for multiple +sections, the results are undefined. </P +></DD +><DT +>section <CODE +CLASS="PARAMETER" +>name</CODE +> load <CODE +CLASS="PARAMETER" +>addr</CODE +></DT +><DD +><P +> This causes the section <CODE +CLASS="PARAMETER" +>name</CODE +> to load at +<CODE +CLASS="PARAMETER" +>addr</CODE +>. For the raw target, only one "load at" entry is +allowed for non-bss sections and it must be the first one. For raw targets, +it affects the addresses the linker assigns to symbols but has no other +affect on the output. bss sections may all have separate load addresses but +since they will not appear in the binary anyway, this is okay.</P +><P +>For the decb target, each "load" entry will cause a new "block" to be +output to the binary which will contain the load address. It is legal for +sections to overlap in this manner - the linker assumes the loader will sort +everything out.</P +></DD +><DT +>section <CODE +CLASS="PARAMETER" +>name</CODE +> high <CODE +CLASS="PARAMETER" +>addr</CODE +></DT +><DD +><P +> This causes the section <CODE +CLASS="PARAMETER" +>name</CODE +> to load with its end +address just below <CODE +CLASS="PARAMETER" +>addr</CODE +>. Subsequent sections are +loaded at progressively lower addresses. This may lead to inefficient file +encoding for some targets. As of this writing, it will also almost +certainly do the wrong thing for a raw target. </P +><P +> This is useful for aligning a block of code with high memory. As an +example, if the total size of a section is $100 bytes and a high address of +$FE00 is specified, the section will actually load at $FD00. </P +></DD +><DT +>section <CODE +CLASS="PARAMETER" +>name</CODE +></DT +><DD +><P +> This will cause the section <CODE +CLASS="PARAMETER" +>name</CODE +> to load after the previously listed +section.</P +></DD +><DT +>entry <CODE +CLASS="PARAMETER" +>addr or sym</CODE +></DT +><DD +><P +>This will cause the execution address (entry point) to be the address +specified (in hex) or the specified symbol name. The symbol name must +match a symbol that is exported by one of the object files being linked. +This has no effect for targets that do not encode the entry point into the +resulting file. If not specified, the entry point is assumed to be address 0 +which is probably not what you want. The default link scripts for targets +that support this directive automatically starts at the beginning of the +first section (usually "init" or "code") that is emitted in the binary.</P +></DD +><DT +>pad <CODE +CLASS="PARAMETER" +>size</CODE +></DT +><DD +><P +>This will cause the output file to be padded with NUL bytes to be exactly +<CODE +CLASS="PARAMETER" +>size</CODE +> bytes in length. This only makes sense for a raw target.</P +></DD +></DL +></DIV +></DIV +><DIV +CLASS="NAVFOOTER" +><HR +ALIGN="LEFT" +WIDTH="100%"><TABLE +SUMMARY="Footer navigation table" +WIDTH="100%" +BORDER="0" +CELLPADDING="0" +CELLSPACING="0" +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +><A +HREF="x928.html" +ACCESSKEY="P" +>Prev</A +></TD +><TD +WIDTH="34%" +ALIGN="center" +VALIGN="top" +><A +HREF="index.html" +ACCESSKEY="H" +>Home</A +></TD +><TD +WIDTH="33%" +ALIGN="right" +VALIGN="top" +><A +HREF="x1008.html" +ACCESSKEY="N" +>Next</A +></TD +></TR +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +>Linker Operation</TD +><TD +WIDTH="34%" +ALIGN="center" +VALIGN="top" +><A +HREF="c828.html" +ACCESSKEY="U" +>Up</A +></TD +><TD +WIDTH="33%" +ALIGN="right" +VALIGN="top" +>Format Specific Linking Notes</TD +></TR +></TABLE +></DIV +></BODY +></HTML +> \ No newline at end of file