Hallo,
ich habe ein Problem mit meinem Linker.
Ich habe mir zwei eigene Sektionen definiert (preboot und boot) und möchte in die boot-Sektion den Multiboot-Header geladen haben.
Leider funktioniert das nicht so ganz und ich weiß nicht warum.
Hier mein Linker-Skript:
/* the linker script to link the kernel */
ENTRY(_start) /* the entry-point of the kernel */
OUTPUT_FORMAT(elf32-i386) /* the output-format */
/* some constants to link the code correctly */
ALIGNMENT = 0x1000; /* the alignment of the sections */
PHYS_ADDRESS = 0x100000; /* the physical address of the kernel */
VIRT_ADDRESS = 0x100000; /* the virtual address of the kernel */
REMAP_OFFSET = VIRT_ADDRESS - PHYS_ADDRESS; /* the offset between physical and virtual addresses */
/* define the different sections of the kernel */
SECTIONS
{
. = VIRT_ADDRESS; /* move the kernel to the correct start-address */
__kernel_virt_entry = .; /* the beginning with virtual addresses */
__kernel_phys_entry = . - REMAP_OFFSET; /* the beginning with physical addresses */
.preboot : AT(ADDR(.preboot) - (REMAP_OFFSET + 0x1000))
{
__preboot_entry = .; /* the entry-symbol to get the space of the preboot-section */
*(.preboot)
__preboot_end = .; /* the end-symbol to get the space of the preboot-section */
}
. = ALIGN(ALIGNMENT);
.boot : AT(ADDR(.boot) - REMAP_OFFSET)
{
__boot_entry = .; /* the entry-symbol of the boot-section */
*(.boot)
__boot_end = .; /* the end-symbol of the boot-section */
}
. = ALIGN(ALIGNMENT);
.init : AT(ADDR(.init) - REMAP_OFFSET)
{
__init_entry = .; /* the entry-symbol of the init-section */
*(.init)
__init_end = .; /* the end-symbol of the init-section */
}
. = ALIGN(ALIGNMENT);
.text : AT(ADDR(.text) - REMAP_OFFSET)
{
__ro_data_entry = .; /* the entry-symbol of the read-only-section */
*(.text)
*(.rodata)
__ro_data_end = .; /* the end-symbol of the read-only-section */
}
. = ALIGN(ALIGNMENT);
.data : AT(ADDR(.data) - REMAP_OFFSET)
{
__rw_data_entry = .; /* the entry-symbol of the read-write-sections */
*(.data)
*(.bss)
__rw_data_end = .; /* the end-symbol of the read-write-sections */
}
. = ALIGN(ALIGNMENT);
__kernel_phys_end = . - REMAP_OFFSET; /* the end of the physical addresses */
__kernel_virt_end = .; /* the end of the virtual addresses */
}
Hier meine Multiboot-Datei:
.section .boot
// the following flags are every time set
#define MB_MAGIC 0x1badb002
/*
* MB_FLAGS[0] == load modules 4k-aligned
* MB_FLAGS[1] == calculate mbs_mem_lower,mbs_mem_upper and mbs_mmap_length, mbs_mmap_addr if possible
* MB_FLAGS[2] == load some informations about the video-mode into the multiboot-structure
* MB_FLAGS[16] == calculates some informations about the kernel-image
*/
#define MB_FLAGS 0x8007
#define MB_CHECKSUM -(MB_MAGIC + MB_FLAGS)
// the following flags are defined, if MB_FLAGS[16] is set
#define MB_HEADER_ADDR 0x0
#define MB_LOAD_ADDR 0x0
#define MB_LOAD_END_ADDR 0x0
#define MB_BSS_END_ADDR 0x0
#define MB_ENTRY_ADDR 0x0
// the following flags are defined, if MB_FLAGS[2] is set
#define MB_MODE_TYPE 0x0
#define MB_MODE_WIDTH 0x0
#define MB_MODE_HEIGHT 0x0
#define MB_MODE_DEPTH 0x0
.align 4
.int MB_MAGIC
.int MB_FLAGS
.int MB_CHECKSUM
.int MB_HEADER_ADDR
.int MB_LOAD_ADDR
.int MB_LOAD_END_ADDR
.int MB_BSS_END_ADDR
.int MB_ENTRY_ADDR
.int MB_MODE_TYPE
.int MB_MODE_WIDTH
.int MB_MODE_HEIGHT
.int MB_MODE_DEPTH
Wenn ich mir nun meine boot-Sektion mir readelf oder objdump anschaue, steht dort nur sinnloses Zeug.
Ausgabe von objdump:
Disassembly of section .boot:
00100000 <__boot_entry>:
100000: 02 b0 ad 1b 07 80 add -0x7ff8e453(%eax),%dh
100006: 00 00 add %al,(%eax)
100008: f7 (bad)
100009: cf iret
10000a: 51 push %ecx
10000b: e4 00 in $0x0,%al
mbchk sagt natürlich, dass es keine Multiboot-Header finden konnte.
Woran kann das Problem liegen?
Danke.
Gruß
rizor
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