Linker scripts: made it possible to override PROCESS_VM_BASE

This turned out to be crucial to be able to debug the issues I was having tonight, so I put the time into fixing this. It turned out to be quite trivial in the end, since a Stack Overflow user had done the vast majority of the work for us. Thanks Aravind! Closes #104.
chaos4ever · Oct 11, 2017 · 177957d · 177957d
1 parent 0906af6
commit 177957d
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Showing 4 changed files with 10 additions and 4 deletions.
diff --git a/libraries/chaos.ld b/libraries/chaos.ld
@@ -10,10 +10,13 @@ OUTPUT_ARCH(i386)
 ENTRY(startup)
 SEARCH_DIR(/mnt/chaos/programming/libraries/static);
 
+DEFAULT_PROCESS_VM_BASE = 0x40000000;
+PROCESS_VM_BASE = DEFINED(PROCESS_VM_BASE) ? PROCESS_VM_BASE : DEFAULT_PROCESS_VM_BASE;
+
 SECTIONS
 {
   /* Read-only sections, merged into text segment: */
-  . = 0x40000000 + SIZEOF_HEADERS;
+  . = PROCESS_VM_BASE + SIZEOF_HEADERS;
   .interp     : { *(.interp) 	}
   .hash          : { *(.hash)		}
   .dynsym        : { *(.dynsym)		}

diff --git a/servers/file_system/fat/Rakefile b/servers/file_system/fat/Rakefile
@@ -22,5 +22,6 @@ LIBRARIES = %w(
 ).freeze
 
 OUTPUT = 'fat'.freeze
+EXTRA_LDFLAGS_PRE = '-Wl,--defsym=PROCESS_VM_BASE=0x50000000'
 
 load '../../servers.rake'
diff --git a/servers/network/ipv4/Rakefile b/servers/network/ipv4/Rakefile
@@ -11,7 +11,7 @@ OBJECTS = %w(
   udp.o
 ).freeze
 
-EXTRA_LDFLAGS = '-lgcc'.freeze
+EXTRA_LIBS = '-lgcc'.freeze
 LIBRARIES = %w(
   ipc
   ipv4

diff --git a/servers/servers.rake b/servers/servers.rake
@@ -38,14 +38,16 @@ CFLAGS = (COMMON_CFLAGS + %w(
   -Wstrict-prototypes
 )).join(' ')
 
-EXTRA_LDFLAGS ||= ''.freeze
+EXTRA_LDFLAGS_PRE ||= ''.freeze
+EXTRA_LIBS ||= ''.freeze
 LDFLAGS = %W(
+  #{EXTRA_LDFLAGS_PRE}
   #{LIBRARIES_DIR}/startup.o
   -nostdlib
   -Wl,-T,#{LIBRARIES_DIR}/chaos.ld
   -m32
   -L#{LIBRARIES_DIR}
-  #{EXTRA_LDFLAGS}
+  #{EXTRA_LIBS}
 ).freeze
 
 LIBRARY_FILES = LIBRARIES.map { |l| "#{LIBRARIES_DIR}/lib#{l}.a" }