Split up source and added basic support for different targets.

SConstruct

@@ -1,52 +1,36 @@
 
 import subprocess
 
+AddOption(
+    '--target',
+    dest = 'target',
+    type = 'choice',
+    choices = ('i686', 'x86_64'),
+    nargs = 1,
+    action = 'store',
+    default = 'i686'
+)
+
+target  = GetOption('target')
+
 env = Environment(tools =  ['default', 'compilation_db'])
-env['AS'] = 'i686-elf-as'
-env['CC'] = 'i686-elf-gcc'
-env['CXX'] = 'i686-elf-g++'
-env['LD'] = 'i686-elf-g++'
 env.Append(CXXFLAGS = ['-ffreestanding', '-fno-exceptions', '-fno-rtti', '-std=c++20'])
 env.Append(LINKFLAGS = ['-T', 'linker.ld', '-ffreestanding', '-nostdlib'])
-env.Append(CPPPATH = ['#include', '#bastl/include'])
+env.Append(CPPPATH = ['#targets/_any/include', '#bastl/include'])
 env.Append(CCFLAGS = ['-g', '-O0'])
 
-def get_crt_object(name: str) -> str:
-    cmd = [env['CXX']]
-    cmd.extend(env['CXXFLAGS'])
-    cmd.append(f'-print-file-name={name}')
-    result = subprocess.run(cmd, stdout=subprocess.PIPE)
-    return result.stdout.decode('utf-8').strip()
-crtbegin_o = get_crt_object('crtbegin.o')
-crtend_o = get_crt_object('crtend.o')
-crti_o = env.Object('src/crt/crti.s')
-crtn_o = env.Object('src/crt/crtn.s')
-
-os_sources = Split('''
-    src/app/main.cpp
-
-    src/kernel/boot.s
-    src/kernel/startup.cpp
-
-    src/os/panic.cpp
-    src/os/tty.cpp
-
-    src/cstdlib/assert.cpp
-    src/cstdlib/stdio.cpp
-    src/cstdlib/stdlib.cpp
-    src/cstdlib/string.cpp
-
-    bastl/src/exception.cpp
-    bastl/src/new.cpp
-''')
-env['LINKCOM'] = env['LINKCOM'].replace('$_LIBFLAGS', f'{crti_o[0]} {crtbegin_o} $_LIBFLAGS {crtend_o} {crtn_o[0]}')
+env['KERNEL_SOURCES'] = []
+env['KERNEL_DEPENDENCIES'] = []
+env = SConscript('bastl/SConscript', exports = 'env')
+env = SConscript('targets/_any/SConscript', exports = 'env')
+env = SConscript(f'targets/{target}/SConscript', exports = 'env')
 
 prog_os = env.Program(
     target = 'os.bin',
-    source = os_sources,
+    source = env['KERNEL_SOURCES'],
     LIBS = ['gcc']
 )
-env.Depends(prog_os, [crti_o, crtn_o])
+env.Depends(prog_os, env['KERNEL_DEPENDENCIES'])
 env.Default(prog_os)
 comp_db = env.CompilationDatabase(target = '#compile_commands.json')
 env.Default(comp_db)

bastl/SConscript

@@ -0,0 +1,10 @@
+Import('env')
+
+bastl_sources = Split('''
+    src/exception.cpp
+    src/new.cpp
+''')
+
+env.Append(KERNEL_SOURCES = [env.File(f) for f in bastl_sources])
+
+Return('env')

targets/_any/SConscript

@@ -0,0 +1,17 @@
+Import('env')
+
+any_target_sources = Split('''
+    src/app/main.cpp
+
+    src/os/panic.cpp
+    src/os/tty.cpp
+
+    src/cstdlib/assert.cpp
+    src/cstdlib/stdio.cpp
+    src/cstdlib/stdlib.cpp
+    src/cstdlib/string.cpp
+''')
+
+env.Append(KERNEL_SOURCES = [env.File(f) for f in any_target_sources])
+
+Return('env')

targets/i686/SConscript

@@ -0,0 +1,31 @@
+Import('env')
+
+env['AS'] = 'i686-elf-as'
+env['CC'] = 'i686-elf-gcc'
+env['CXX'] = 'i686-elf-g++'
+env['LD'] = 'i686-elf-g++'
+
+def get_crt_object(name: str) -> str:
+    import subprocess
+
+    cmd = [env['CXX']]
+    cmd.extend(env['CXXFLAGS'])
+    cmd.append(f'-print-file-name={name}')
+    result = subprocess.run(cmd, stdout=subprocess.PIPE)
+    return result.stdout.decode('utf-8').strip()
+crtbegin_o = get_crt_object('crtbegin.o')
+crtend_o = get_crt_object('crtend.o')
+crti_o = env.Object('src/crt/crti.s')
+crtn_o = env.Object('src/crt/crtn.s')
+
+i686_sources = Split('''
+    src/kernel/boot.s
+    src/kernel/startup.cpp
+''')
+
+env['LINKCOM'] = env['LINKCOM'].replace('$_LIBFLAGS', f'{crti_o[0].abspath} {crtbegin_o} $_LIBFLAGS {crtend_o} {crtn_o[0].abspath}')
+
+env.Append(KERNEL_SOURCES = [env.File(f) for f in i686_sources])
+env.Append(KERNEL_DEPENDENCIES = [crti_o, crtn_o])
+
+Return('env')

targets/x86_64/SConscript

@@ -0,0 +1,32 @@
+Import('env')
+
+env['AS'] = 'x86_64-elf-as'
+env['CC'] = 'x86_64-elf-gcc'
+env['CXX'] = 'x86_64-elf-g++'
+env['LD'] = 'x86_64-elf-g++'
+
+def get_crt_object(name: str) -> str:
+    import subprocess
+
+    cmd = [env['CXX']]
+    cmd.extend(env['CXXFLAGS'])
+    cmd.append(f'-print-file-name={name}')
+    result = subprocess.run(cmd, stdout=subprocess.PIPE)
+    return result.stdout.decode('utf-8').strip()
+crtbegin_o = get_crt_object('crtbegin.o')
+crtend_o = get_crt_object('crtend.o')
+crti_o = env.Object('src/crt/crti.s')
+crtn_o = env.Object('src/crt/crtn.s')
+
+i686_sources = Split('''
+    src/kernel/boot.s
+    src/kernel/startup.cpp
+''')
+
+env['LINKCOM'] = env['LINKCOM'].replace('$_LIBFLAGS', f'{crti_o[0].abspath} {crtbegin_o} $_LIBFLAGS {crtend_o} {crtn_o[0].abspath}')
+
+env.Append(KERNEL_SOURCES = [env.File(f) for f in i686_sources])
+env.Append(KERNEL_DEPENDENCIES = [crti_o, crtn_o])
+env.Append(LINKFLAGS = ['-mcmodel=large', '-mno-red-zone', '-mno-mmx', '-mno-sse', '-mno-sse2'])
+
+Return('env')

targets/x86_64/src/crt/crti.s

@@ -0,0 +1,16 @@
+/* x86 crti.s */
+.section .init
+.global _init
+.type _init, @function
+_init:
+	push %rbp
+	movl %esp, %ebp
+	/* gcc will nicely put the contents of crtbegin.o's .init section here. */
+
+.section .fini
+.global _fini
+.type _fini, @function
+_fini:
+	push %rbp
+	movl %esp, %ebp
+	/* gcc will nicely put the contents of crtbegin.o's .fini section here. */

targets/x86_64/src/crt/crtn.s

@@ -0,0 +1,10 @@
+/* x86 crtn.s */
+.section .init
+	/* gcc will nicely put the contents of crtend.o's .init section here. */
+	pop %rbp
+	ret
+
+.section .fini
+	/* gcc will nicely put the contents of crtend.o's .fini section here. */
+	pop %rbp
+	ret

targets/x86_64/src/kernel/boot.s

@@ -0,0 +1,79 @@
+// constants for the multiboot header
+.set ALIGN,    1<<0             /* align loaded modules on page boundaries */
+.set MEMINFO,  1<<1             /* provide memory map */
+.set FLAGS,    ALIGN | MEMINFO  /* this is the Multiboot 'flag' field */
+.set MAGIC,    0x1BADB002       /* 'magic number' lets bootloader find the header */
+.set CHECKSUM, -(MAGIC + FLAGS) /* checksum of above, to prove we are multiboot */
+
+// the actual multiboot header
+.section .multiboot
+.align 4
+.long MAGIC
+.long FLAGS
+.long CHECKSUM
+
+// stack section
+.section .bss
+.align 16
+stack_bottom:
+.skip 16384 # 16 KiB
+stack_top:
+
+// kernel entry point
+.section .text
+.global _start
+.type _start, @function
+_start:
+	/*
+	The bootloader has loaded us into 32-bit protected mode on a x86
+	machine. Interrupts are disabled. Paging is disabled. The processor
+	state is as defined in the multiboot standard. The kernel has full
+	control of the CPU. The kernel can only make use of hardware features
+	and any code it provides as part of itself. There's no printf
+	function, unless the kernel provides its own <stdio.h> header and a
+	printf implementation. There are no security restrictions, no
+	safeguards, no debugging mechanisms, only what the kernel provides
+	itself. It has absolute and complete power over the
+	machine.
+	*/
+
+    // store the multiboot info
+    mov %ebx, (gMultibootHeader)
+
+	// setup stack
+	mov $stack_top, %esp
+
+    // call the constructors
+    mov  $start_ctors, %ebx
+    jmp  .ctors_loop_end
+.ctors_loop_start:
+    call *(%ebx)
+    add  4, %ebx
+.ctors_loop_end:
+    cmp  $end_ctors, %ebx
+    jb   .ctors_loop_start
+
+	// enter high-level kernel
+	call kernel_main
+
+//	// call the destructors
+//	mov $start_dtors, %ebx
+//	jmp .dtors_loop_end
+//.dtors_loop_start:
+//    call *(%ebx)
+//    add 4, %ebx
+//.dtors_loop_end:
+//    cmp $end_dtors, %ebx
+//    jb .dtors_loop_start
+
+	// We are done. Clear interrupts and halt.
+	cli
+.kernel_end:
+	hlt
+	jmp .kernel_end
+
+/*
+Set the size of the _start symbol to the current location '.' minus its start.
+This is useful when debugging or when you implement call tracing.
+*/
+.size _start, . - _start

targets/x86_64/src/kernel/multiboot.h

@@ -0,0 +1,274 @@
+/* multiboot.h - Multiboot header file. */
+/* Copyright (C) 1999,2003,2007,2008,2009,2010  Free Software Foundation, Inc.
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy
+ *  of this software and associated documentation files (the "Software"), to
+ *  deal in the Software without restriction, including without limitation the
+ *  rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ *  sell copies of the Software, and to permit persons to whom the Software is
+ *  furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in
+ *  all copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL ANY
+ *  DEVELOPER OR DISTRIBUTOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ *  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+ *  IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef MULTIBOOT_HEADER
+#define MULTIBOOT_HEADER 1
+
+/* How many bytes from the start of the file we search for the header. */
+#define MULTIBOOT_SEARCH                        8192
+#define MULTIBOOT_HEADER_ALIGN                  4
+
+/* The magic field should contain this. */
+#define MULTIBOOT_HEADER_MAGIC                  0x1BADB002
+
+/* This should be in %eax. */
+#define MULTIBOOT_BOOTLOADER_MAGIC              0x2BADB002
+
+/* Alignment of multiboot modules. */
+#define MULTIBOOT_MOD_ALIGN                     0x00001000
+
+/* Alignment of the multiboot info structure. */
+#define MULTIBOOT_INFO_ALIGN                    0x00000004
+
+/* Flags set in the ’flags’ member of the multiboot header. */
+
+/* Align all boot modules on i386 page (4KB) boundaries. */
+#define MULTIBOOT_PAGE_ALIGN                    0x00000001
+
+/* Must pass memory information to OS. */
+#define MULTIBOOT_MEMORY_INFO                   0x00000002
+
+/* Must pass video information to OS. */
+#define MULTIBOOT_VIDEO_MODE                    0x00000004
+
+/* This flag indicates the use of the address fields in the header. */
+#define MULTIBOOT_AOUT_KLUDGE                   0x00010000
+
+/* Flags to be set in the ’flags’ member of the multiboot info structure. */
+
+/* is there basic lower/upper memory information? */
+#define MULTIBOOT_INFO_MEMORY                   0x00000001
+/* is there a boot device set? */
+#define MULTIBOOT_INFO_BOOTDEV                  0x00000002
+/* is the command-line defined? */
+#define MULTIBOOT_INFO_CMDLINE                  0x00000004
+/* are there modules to do something with? */
+#define MULTIBOOT_INFO_MODS                     0x00000008
+
+/* These next two are mutually exclusive */
+
+/* is there a symbol table loaded? */
+#define MULTIBOOT_INFO_AOUT_SYMS                0x00000010
+/* is there an ELF section header table? */
+#define MULTIBOOT_INFO_ELF_SHDR                 0X00000020
+
+/* is there a full memory map? */
+#define MULTIBOOT_INFO_MEM_MAP                  0x00000040
+
+/* Is there drive info? */
+#define MULTIBOOT_INFO_DRIVE_INFO               0x00000080
+
+/* Is there a config table? */
+#define MULTIBOOT_INFO_CONFIG_TABLE             0x00000100
+
+/* Is there a boot loader name? */
+#define MULTIBOOT_INFO_BOOT_LOADER_NAME         0x00000200
+
+/* Is there a APM table? */
+#define MULTIBOOT_INFO_APM_TABLE                0x00000400
+
+/* Is there video information? */
+#define MULTIBOOT_INFO_VBE_INFO                 0x00000800
+#define MULTIBOOT_INFO_FRAMEBUFFER_INFO         0x00001000
+
+#ifndef ASM_FILE
+
+typedef unsigned char           multiboot_uint8_t;
+typedef unsigned short          multiboot_uint16_t;
+typedef unsigned int            multiboot_uint32_t;
+typedef unsigned long long      multiboot_uint64_t;
+
+struct multiboot_header
+{
+    /* Must be MULTIBOOT_MAGIC - see above. */
+    multiboot_uint32_t magic;
+
+    /* Feature flags. */
+    multiboot_uint32_t flags;
+
+    /* The above fields plus this one must equal 0 mod 2^32. */
+    multiboot_uint32_t checksum;
+
+    /* These are only valid if MULTIBOOT_AOUT_KLUDGE is set. */
+    multiboot_uint32_t header_addr;
+    multiboot_uint32_t load_addr;
+    multiboot_uint32_t load_end_addr;
+    multiboot_uint32_t bss_end_addr;
+    multiboot_uint32_t entry_addr;
+
+    /* These are only valid if MULTIBOOT_VIDEO_MODE is set. */
+    multiboot_uint32_t mode_type;
+    multiboot_uint32_t width;
+    multiboot_uint32_t height;
+    multiboot_uint32_t depth;
+};
+
+/* The symbol table for a.out. */
+struct multiboot_aout_symbol_table
+{
+    multiboot_uint32_t tabsize;
+    multiboot_uint32_t strsize;
+    multiboot_uint32_t addr;
+    multiboot_uint32_t reserved;
+};
+typedef struct multiboot_aout_symbol_table multiboot_aout_symbol_table_t;
+
+/* The section header table for ELF. */
+struct multiboot_elf_section_header_table
+{
+    multiboot_uint32_t num;
+    multiboot_uint32_t size;
+    multiboot_uint32_t addr;
+    multiboot_uint32_t shndx;
+};
+typedef struct multiboot_elf_section_header_table multiboot_elf_section_header_table_t;
+
+struct multiboot_info
+{
+    /* Multiboot info version number */
+    multiboot_uint32_t flags;
+
+    /* Available memory from BIOS */
+    multiboot_uint32_t mem_lower;
+    multiboot_uint32_t mem_upper;
+
+    /* "root" partition */
+    multiboot_uint32_t boot_device;
+
+    /* Kernel command line */
+    multiboot_uint32_t cmdline;
+
+    /* Boot-Module list */
+    multiboot_uint32_t mods_count;
+    multiboot_uint32_t mods_addr;
+
+    union
+    {
+        multiboot_aout_symbol_table_t aout_sym;
+        multiboot_elf_section_header_table_t elf_sec;
+    } u;
+
+    /* Memory Mapping buffer */
+    multiboot_uint32_t mmap_length;
+    multiboot_uint32_t mmap_addr;
+
+    /* Drive Info buffer */
+    multiboot_uint32_t drives_length;
+    multiboot_uint32_t drives_addr;
+
+    /* ROM configuration table */
+    multiboot_uint32_t config_table;
+
+    /* Boot Loader Name */
+    multiboot_uint32_t boot_loader_name;
+
+    /* APM table */
+    multiboot_uint32_t apm_table;
+
+    /* Video */
+    multiboot_uint32_t vbe_control_info;
+    multiboot_uint32_t vbe_mode_info;
+    multiboot_uint16_t vbe_mode;
+    multiboot_uint16_t vbe_interface_seg;
+    multiboot_uint16_t vbe_interface_off;
+    multiboot_uint16_t vbe_interface_len;
+
+    multiboot_uint64_t framebuffer_addr;
+    multiboot_uint32_t framebuffer_pitch;
+    multiboot_uint32_t framebuffer_width;
+    multiboot_uint32_t framebuffer_height;
+    multiboot_uint8_t framebuffer_bpp;
+#define MULTIBOOT_FRAMEBUFFER_TYPE_INDEXED 0
+#define MULTIBOOT_FRAMEBUFFER_TYPE_RGB     1
+#define MULTIBOOT_FRAMEBUFFER_TYPE_EGA_TEXT     2
+    multiboot_uint8_t framebuffer_type;
+    union
+    {
+        struct
+        {
+            multiboot_uint32_t framebuffer_palette_addr;
+            multiboot_uint16_t framebuffer_palette_num_colors;
+        };
+        struct
+        {
+            multiboot_uint8_t framebuffer_red_field_position;
+            multiboot_uint8_t framebuffer_red_mask_size;
+            multiboot_uint8_t framebuffer_green_field_position;
+            multiboot_uint8_t framebuffer_green_mask_size;
+            multiboot_uint8_t framebuffer_blue_field_position;
+            multiboot_uint8_t framebuffer_blue_mask_size;
+        };
+    };
+};
+typedef struct multiboot_info multiboot_info_t;
+
+struct multiboot_color
+{
+    multiboot_uint8_t red;
+    multiboot_uint8_t green;
+    multiboot_uint8_t blue;
+};
+
+struct multiboot_mmap_entry
+{
+    multiboot_uint32_t size;
+    multiboot_uint64_t addr;
+    multiboot_uint64_t len;
+#define MULTIBOOT_MEMORY_AVAILABLE              1
+#define MULTIBOOT_MEMORY_RESERVED               2
+#define MULTIBOOT_MEMORY_ACPI_RECLAIMABLE       3
+#define MULTIBOOT_MEMORY_NVS                    4
+#define MULTIBOOT_MEMORY_BADRAM                 5
+    multiboot_uint32_t type;
+} __attribute__((packed));
+typedef struct multiboot_mmap_entry multiboot_memory_map_t;
+
+struct multiboot_mod_list
+{
+    /* the memory used goes from bytes ’mod_start’ to ’mod_end-1’ inclusive */
+    multiboot_uint32_t mod_start;
+    multiboot_uint32_t mod_end;
+
+    /* Module command line */
+    multiboot_uint32_t cmdline;
+
+    /* padding to take it to 16 bytes (must be zero) */
+    multiboot_uint32_t pad;
+};
+typedef struct multiboot_mod_list multiboot_module_t;
+
+/* APM BIOS info. */
+struct multiboot_apm_info
+{
+    multiboot_uint16_t version;
+    multiboot_uint16_t cseg;
+    multiboot_uint32_t offset;
+    multiboot_uint16_t cseg_16;
+    multiboot_uint16_t dseg;
+    multiboot_uint16_t flags;
+    multiboot_uint16_t cseg_len;
+    multiboot_uint16_t cseg_16_len;
+    multiboot_uint16_t dseg_len;
+};
+
+#endif /* ! ASM_FILE */
+
+#endif /* ! MULTIBOOT_HEADER */

targets/x86_64/src/kernel/startup.cpp

@@ -0,0 +1,70 @@
+
+#include "os/tty.hpp"
+
+#include <cassert>
+#include <cstdio>
+#include <cstdlib>
+#include "./multiboot.h"
+
+extern "C" int gKernelEnd;
+
+namespace
+{
+void initHeapFromMultibootHeader(const uint32_t firstEntryAddr, const size_t bufferLength) noexcept
+{
+    const uint64_t minAddr = reinterpret_cast<uint64_t>(&gKernelEnd);
+    for (uint32_t addr = firstEntryAddr; addr < firstEntryAddr + bufferLength;)
+    {
+        multiboot_memory_map_t entry = *reinterpret_cast<multiboot_memory_map_t*>(addr);
+
+        if(entry.type == MULTIBOOT_MEMORY_AVAILABLE)
+        {
+            std::printf("Start Addr: %X | Length: %b\n",
+                        static_cast<unsigned>(entry.addr), static_cast<size_t>(entry.len));
+
+            // anything before the kernel we ignore
+            if (entry.addr < minAddr)
+            {
+                // if the entire entry is before the kernel, continue
+                if (entry.addr + entry.len <= minAddr)
+                {
+                    addr += sizeof(entry.size) + entry.size;
+                    continue;
+                }
+                // otherwise shrink it and use the rest
+                entry.len -= (minAddr - entry.addr);
+                entry.addr = minAddr;
+            }
+            __ba_registerAllocatableMemory(reinterpret_cast<void*>(entry.addr), entry.len);
+        }
+        addr += sizeof(entry.size) + entry.size;
+    }
+}
+}
+
+extern "C"
+{
+multiboot_info_t* gMultibootHeader;
+
+void _init();
+void _fini();
+void main();
+
+void kernel_main()
+{
+    _init();
+
+	/* Initialize terminal interface */
+	tty::initialize();
+
+    std::printf("Kernel End: %p\n", &gKernelEnd);
+
+    /* Initialize the heap */
+    assert(gMultibootHeader->flags & MULTIBOOT_INFO_MEM_MAP);
+    initHeapFromMultibootHeader(gMultibootHeader->mmap_addr, gMultibootHeader->mmap_length);
+
+    main();
+
+    _fini();
+}
+} // extern "C"