Linker script rework

`memory.ld` is a architecture-dependent ld config provides some general
    symbols which every `memory.ld` config must assign
    and memory regions associated with each output section.

'linker.ld' config file presents segments configuration.

Multiboot section filling move in the 'linker.ld' file.

Recommendation for further patches: controlled logic implementation for multiboot
    version and header/entries in build configuration tool (CMake or
    make). For instance, multiboot version and video mode selection
    through variable passing in build system:
    `cmake ... -DMULTIBOOT_VERSION=2 -DMULTIBOOT_VIDEO_MODE=TEXT_VIDEO_MODE`
    or
    'export MULTIBOOT_VERSION=2; export MULTIBOOT_VIDEO_MODE=TEXT_VIDEO_MODE'.
    Then build system do proper filling of `.multiboot` section depends
    on passing variables.

Signed-off-by: Alexey Gavrilov <alexey.gavrilov@mail.com>

4 files changed, 77 insertions, 59 deletions

diff --git a/arch/x86/memory.ld b/arch/x86/memory.ld
new file mode 100644
index 0000000..0226aca
--- /dev/null
+++ b/arch/x86/memory.ld
@@ -0,0 +1,13 @@
+MEMORY
+    {
+        RAM : ORIGIN = 0x00100000, LENGTH = 1M
+    }
+
+REGION_ALIAS("REGION_MULTIBOOT", RAM);
+REGION_ALIAS("REGION_TEXT", RAM);
+REGION_ALIAS("REGION_RODATA", RAM);
+REGION_ALIAS("REGION_DATA", RAM);
+REGION_ALIAS("REGION_BSS", RAM);
+REGION_ALIAS("REGION_COMMON", RAM);
+
+PROVIDE(START_ADDR = ORIGIN(RAM));
diff --git a/kernel/boot.s b/kernel/boot.s
index 534beb6..281e1ca 100644
--- a/kernel/boot.s
+++ b/kernel/boot.s
@@ -1,36 +1,11 @@
-MBFLAGS equ 0
-MAGIC equ 0x1BADB002
-CHECKSUM equ -(MAGIC + MBFLAGS)
-
-            section .multiboot
-align 4
-    dd MAGIC
-    dd MBFLAGS
-    dd CHECKSUM
-
-section .bss
-resb 512
-align 16
-; align 16 bytes according to the System V ABI standard
-; Stack space
-stack_bottom:
-resb 16384 ; 16KiB
-stack_top:
-
 section .text
 extern main
+extern _estack
 global _start:function (_start.end - _start)
 _start:
-            mov esp, stack_top
+            mov esp, _estack
             call main
             cli
 .hang:      hlt
             jmp .hang
 .end:
-
-section .kheap
-kheap_top:
-; Kernel heap space
-; Change this value together Kheap::size varibale (mem/Kheap.h file)
-resb 4096
-kheap_bottom:
diff --git a/kernel/linker.ld b/kernel/linker.ld
index abee596..9a0561b 100644
--- a/kernel/linker.ld
+++ b/kernel/linker.ld
@@ -1,49 +1,77 @@
+INCLUDE memory.ld
+
 ENTRY(_start)
 
+/*Pass this symbols via CMake*/
+MAGIC = 0x1BADB002;
+FLAGS = 0;
+CHECKSUM = -(MAGIC + FLAGS);
+
 SECTIONS
 {
-    . = 1M;
-
-    .multiboot :
+    /* It's a raw solution. */
+    /* Automatic generation of filling .multiboot section needs. */
+    .multiboot ALIGN(START_ADDR, CONSTANT(MAXPAGESIZE)) : ALIGN(CONSTANT(MAXPAGESIZE))
     {
-        _startMultiboot = .;
-        *(.multiboot)
-        _endMultiboot = .;
-    }
+        LONG(MAGIC);
+        LONG(FLAGS);
+        LONG(CHECKSUM)
+    } > REGION_MULTIBOOT
 
-    .text BLOCK(4K) : ALIGN(4K)
+    .text ALIGN(CONSTANT(MAXPAGESIZE)) : ALIGN(CONSTANT(MAXPAGESIZE))
     {
-        _startText = .;
-        *(.text)
-        _endText = .;
-    }
+        _text = .;
+        *(.text*)
+        _etext = .;
+    } > REGION_TEXT
 
-    .rodata BLOCK(4K) : ALIGN(4k)
+    .rodata ALIGN(CONSTANT(MAXPAGESIZE)): ALIGN(CONSTANT(MAXPAGESIZE))
     {
-        _startRodata = .;
-        *(.rodata)
-        _endRodata = .;
-    }
+        _rodata = .;
+        *(.rodata*)
+        _erodata = .;
+    } > REGION_RODATA
 
-    .data BLOCK(4K) : ALIGN(4K)
+    .data :
     {
-        _startData = .;
+        _data = .;
         *(.data)
-        _endData = .;
-    }
+        _edata = .;
+    } > REGION_DATA
 
-    .bss BLOCK(16K) : ALIGN(16K)
+    .bss :
     {
-        _startBss = .;
+        _bss = .;
         *(.bss)
-        _endBss = .;
-    }
+        *(COMMON)
+        _ebss = .;
+    } > REGION_BSS
+
+    .stack ALIGN(CONSTANT(MAXPAGESIZE)) : ALIGN(CONSTANT(MAXPAGESIZE))
+    {
+        _stack = ABSOLUTE(.);
+        . += 4 * CONSTANT(MAXPAGESIZE);
+        _estack = ABSOLUTE(.);
+    } > REGION_DATA
 
-    .kheap BLOCK(4k) : ALIGN(4k)
+    .kheap ALIGN(CONSTANT(MAXPAGESIZE)) : ALIGN(CONSTANT(MAXPAGESIZE))
     {
-        _startKheap = .;
-        *(.kheap)
-        _endKheap = .;
-    }
+        _startKheap = ABSOLUTE(.);
+        . += CONSTANT(MAXPAGESIZE);
+        _endKheap = ABSOLUTE(.);
+    } > REGION_DATA
+
+    .eh_frame :
+    {
+        _eh_frame = .;
+        *(.eh_frame)
+        _e_eh_frame = .;
+    } > REGION_COMMON
+
+    .ctors :
+    {
+        SORT_BY_NAME(CONSTRUCTORS)
+    } > REGION_COMMON
+
 
 }
diff --git a/makefile b/makefile
index fc3286a..051eb0e 100644
--- a/makefile
+++ b/makefile
@@ -9,10 +9,12 @@ QEMUFLAGS =
 
 CFILES = $(shell find ./ -type f \( -name \*.cpp -o -name \*.c \))
 AFILES = $(shell find ./ -type f \( -iname \*.s -o -name \*.asm \))
-LDFILE = $(shell find ./ -type f -name *.ld)
+LDFILE = ./kernel/linker.ld
 SOURCE_FILES = $(CFILES) $(AFILES)
 OBJ_FILES = $(addprefix $(BDIR)/, $(addsuffix .o, $(basename $(SOURCE_FILES))))
 INCLUDE = ./include
+# Bad practice!
+ARCHDIR = arch/x86
 
 ifdef DEBUG
 	CFLAGS := -g3 $(CFLAGS)
@@ -29,7 +31,7 @@ build: startbuild $(SOURCE_FILES)
 	echo $(AFLAGS)
 	echo $(CFLAGS)
 	@echo "Link object files..."
-	$(LD) -o $(OS_BINARY) -T $(LDFILE) $(OBJ_FILES) $(LDFLAGS) 
+	$(LD) -o $(OS_BINARY) -L$(ARCHDIR) -T$(LDFILE) $(OBJ_FILES) $(LDFLAGS) 
 	@echo "Project was built"
 
 $(CFILES):