Update linux build script to run on modern tools

sivasankarankb · Feb 14, 2023 · 9759c36 · 9759c36
1 parent 31c8696
commit 9759c36
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Showing 2 changed files with 22 additions and 4 deletions.
diff --git a/extras/BUILD.md b/extras/BUILD.md
@@ -7,8 +7,8 @@ These were removed from the old sources as they no longer require to be built.
 Those sources were kept only for historic reasons.
 
 These files were re-created. There were no build scripts for Linux distros
-back then. A simple translation to linux commands has been done.
-Copy the scripts to the outermost directory before running.
+back then. The included Linux script has been tested on very modern build
+tools. Copy the scripts to the outermost directory before running.
 
 
 v0.1.0
@@ -51,3 +51,20 @@ v0.1.0
   the definition from `ports.c` to `proto.h`. Place it below the `io_wait()`
   declaration there.
 
+- \[07\] (Fix included in Linux build script)
+
+  Modern x86-64 tools have to be instructed to produce 32bit code explicitly.
+  The `-m32` GCC flag and i386 ELF emulation in LD with `-melf_i386` seems
+  to do the trick as of now.
+
+- \[08\] (Fix included in Linux build script)
+
+  Modern Linux builds of GCC produce position independent executables (PIEs) by
+  default. The kernel is always loaded to a fixed address. PIE generation is
+  disabled with the `-fno-pie` switch.
+
+- \[09\] (Fix included in Linux build script)
+
+  A stack smash protector added by GCC requires handling from within the kernel.
+  This was never implemented in the original kernel code. This feature is
+  disabled with the `-fno-stack-protector` flag.
diff --git a/extras/linux-build.sh b/extras/linux-build.sh
@@ -3,7 +3,8 @@ clear
 
 # GNU/Linux GCC Build Script for Blaze OS v0.1.0
 
-CFLAGS="-c -nostdinc -nostdlib -ffreestanding -march=i386 -fleading-underscore"
+CFLAGS="-c -nostdinc -nostdlib -ffreestanding -march=i386 -fleading-underscore \
+-fno-pie -fno-stack-protector -m32"
 CFILES="kernel irq isr itext memmgr pic ports ps2"
 CFILECOUNT=$(echo "$CFILES" | wc -w)
 SRCCOUNT=$(($CFILECOUNT + 1))
@@ -32,7 +33,7 @@ for CSOURCE in ${CFILES}; do
 
 echo "4 of 6 Create kernel binary"
 
-ld obj/idt.o obj/libk.a -T linker.ld -o obj/ldkern.o
+ld -melf_i386 obj/idt.o obj/libk.a -T linker.ld -o obj/ldkern.o
 objcopy -R .note -R .comment -S -g -O binary obj/ldkern.o bin/kernel.bin
 
 echo "5 of 6 Create boot disk image"