From fe52f8e8bef150c50e88c78ccc1f2b75a8d0f192 Mon Sep 17 00:00:00 2001
From: Michael Brown <mcb30@ipxe.org>
Date: Sat, 30 Jan 2021 01:35:27 +0000
Subject: [PATCH] [build] Avoid modifying load addresses when stripping .zinfo
 section

Some versions of objcopy will spuriously complain when asked to
extract the .zinfo section since doing so will nominally alter the
load addresses of the (non-loadable) .bss.* sections.

Avoid these warnings by placing the .zinfo section at the very end of
the load memory address space.

Allocate non-overlapping load memory addresses for the (non-loadable)
.bss.* sections, in the hope of avoiding spurious warnings about
overlapping load addresses.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
---
 src/arch/x86/scripts/pcbios.lds | 49 ++++++++++++++++++++++++++++-----
 1 file changed, 42 insertions(+), 7 deletions(-)

diff --git a/src/arch/x86/scripts/pcbios.lds b/src/arch/x86/scripts/pcbios.lds
index c9a91c02b..62442138f 100644
--- a/src/arch/x86/scripts/pcbios.lds
+++ b/src/arch/x86/scripts/pcbios.lds
@@ -58,11 +58,12 @@ SECTIONS {
 	*(SORT(.pci_devlist.*))
 	*(.prefix.*)
 	_mprefix = .;
-    } .bss.prefix (NOLOAD) : AT ( _end_lma ) {
+    } .bss.prefix (NOLOAD) : AT ( _bss_prefix_lma ) {
 	_eprefix = .;
     }
     _prefix_filesz	= ABSOLUTE ( _mprefix ) - ABSOLUTE ( _prefix );
     _prefix_memsz	= ABSOLUTE ( _eprefix ) - ABSOLUTE ( _prefix );
+    _prefix_padsz	= ABSOLUTE ( _eprefix ) - ABSOLUTE ( _mprefix );
 
     /*
      * The 16-bit (real-mode) code section
@@ -82,7 +83,7 @@ SECTIONS {
 	*(.text16)
 	*(.text16.*)
 	_mtext16 = .;
-    } .bss.text16 (NOLOAD) : AT ( _end_lma ) {
+    } .bss.text16 (NOLOAD) : AT ( _bss_text16_lma ) {
 	_etext16 = .;
     }
     _text16_early_filesz = ABSOLUTE ( _etext16_early ) - ABSOLUTE ( _text16 );
@@ -90,6 +91,7 @@ SECTIONS {
     _text16_late_filesz	= ABSOLUTE ( _mtext16 ) - ABSOLUTE ( _text16_late );
     _text16_late_memsz	= ABSOLUTE ( _etext16 ) - ABSOLUTE ( _text16_late );
     _text16_memsz	= ABSOLUTE ( _etext16 ) - ABSOLUTE ( _text16 );
+    _text16_padsz	= ABSOLUTE ( _etext16 ) - ABSOLUTE ( _mtext16 );
 
     /*
      * The 16-bit (real-mode) data section
@@ -104,7 +106,7 @@ SECTIONS {
 	*(.data16)
 	*(.data16.*)
 	_mdata16 = .;
-    } .bss.data16 (NOLOAD) : AT ( _end_lma ) {
+    } .bss.data16 (NOLOAD) : AT ( _bss_data16_lma ) {
 	*(.bss16)
 	*(.bss16.*)
 	*(.stack16)
@@ -114,6 +116,7 @@ SECTIONS {
     }
     _data16_filesz	= ABSOLUTE ( _mdata16 ) - ABSOLUTE ( _data16 );
     _data16_memsz	= ABSOLUTE ( _edata16 ) - ABSOLUTE ( _data16 );
+    _data16_padsz	= ABSOLUTE ( _edata16 ) - ABSOLUTE ( _mdata16 );
 
     /*
      * The 32-bit sections
@@ -135,7 +138,7 @@ SECTIONS {
 	KEEP(*(.provided))
 	KEEP(*(.provided.*))
 	_mtextdata = .;
-    } .bss.textdata (NOLOAD) : AT ( _end_lma ) {
+    } .bss.textdata (NOLOAD) : AT ( _bss_textdata_lma ) {
 	*(.bss)
 	*(.bss.*)
 	*(COMMON)
@@ -157,6 +160,7 @@ SECTIONS {
     }
     _textdata_filesz	= ABSOLUTE ( _mtextdata ) - ABSOLUTE ( _textdata );
     _textdata_memsz	= ABSOLUTE ( _etextdata ) - ABSOLUTE ( _textdata );
+    _textdata_padsz	= ABSOLUTE ( _etextdata ) - ABSOLUTE ( _mtextdata );
 
     /*
      * Payload prefix
@@ -169,11 +173,12 @@ SECTIONS {
 	KEEP(*(.pprefix))
 	KEEP(*(.pprefix.*))
 	_mpprefix = .;
-    } .bss.pprefix (NOLOAD) : AT ( _end_lma ) {
+    } .bss.pprefix (NOLOAD) : AT ( _bss_pprefix_lma ) {
 	_epprefix = .;
     }
     _pprefix_filesz	= ABSOLUTE ( _mpprefix ) - ABSOLUTE ( _pprefix );
     _pprefix_memsz	= ABSOLUTE ( _epprefix ) - ABSOLUTE ( _pprefix );
+    _pprefix_padsz	= ABSOLUTE ( _epprefix ) - ABSOLUTE ( _mpprefix );
 
     /*
      * Compressor information block
@@ -185,11 +190,12 @@ SECTIONS {
 	KEEP(*(.zinfo))
 	KEEP(*(.zinfo.*))
 	_mzinfo = .;
-    } .bss.zinfo (NOLOAD) : AT ( _end_lma ) {
+    } .bss.zinfo (NOLOAD) : AT ( _bss_zinfo_lma ) {
 	_ezinfo = .;
     }
     _zinfo_filesz	= ABSOLUTE ( _mzinfo ) - ABSOLUTE ( _zinfo );
     _zinfo_memsz	= ABSOLUTE ( _ezinfo ) - ABSOLUTE ( _zinfo );
+    _zinfo_padsz	= ABSOLUTE ( _ezinfo ) - ABSOLUTE ( _mzinfo );
 
     /*
      * Weak symbols that need zero values if not otherwise defined
@@ -260,7 +266,36 @@ SECTIONS {
     _textdata_lma	= .;
     .			+= _textdata_filesz;
 
-    _filesz		= .; /* Do not include zinfo block in file size */
+    _filesz		= .; /* Do not include .bss.* or .zinfo in file size */
+
+    /*
+     * Dummy load addresses for .bss.* and .zinfo sections
+     *
+     */
+
+    .			= ALIGN ( _max_align );
+    _bss_prefix_lma	= .;
+    .			+=  _prefix_padsz;
+
+    .			= ALIGN ( _max_align );
+    _bss_text16_lma	= .;
+    .			+= _text16_padsz;
+
+    .			= ALIGN ( _max_align );
+    _bss_data16_lma	= .;
+    .			+= _data16_padsz;
+
+    .			= ALIGN ( _max_align );
+    _bss_textdata_lma	= .;
+    .			+= _textdata_padsz;
+
+    .			= ALIGN ( _max_align );
+    _bss_pprefix_lma	= .;
+    .			+= _pprefix_padsz;
+
+    .			= ALIGN ( _max_align );
+    _bss_zinfo_lma	= .;
+    .			+= _zinfo_padsz;
 
     .			= ALIGN ( _max_align );
     _zinfo_lma		= .;