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Implemented mmap storage, mem allocation etc.

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This commit is contained in:
Thomas Oltmann 2025-07-05 15:30:38 +02:00
parent 54476eeea1
commit 77d791f177
3 changed files with 258 additions and 25 deletions
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155
bootboot.h Normal file
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@ -0,0 +1,155 @@
/*
* bootboot.h
* https://gitlab.com/bztsrc/bootboot
*
* Copyright (C) 2017 - 2021 bzt (bztsrc@gitlab)
*
* 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 THE AUTHORS OR COPYRIGHT
* HOLDERS 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.
*
* This file is part of the BOOTBOOT Protocol package.
* @brief The BOOTBOOT structure
*
*/
#ifndef _BOOTBOOT_H_
#define _BOOTBOOT_H_
#ifdef __cplusplus
extern "C" {
#endif
#ifndef _MSC_VER
#define _pack __attribute__((packed))
#else
#define _pack
#pragma pack(push)
#pragma pack(1)
#endif
#define BOOTBOOT_MAGIC "BOOT"
/* default virtual addresses for level 0 and 1 static loaders */
#define BOOTBOOT_MMIO 0xfffffffff8000000 /* memory mapped IO virtual address */
#define BOOTBOOT_FB 0xfffffffffc000000 /* frame buffer virtual address */
#define BOOTBOOT_INFO 0xffffffffffe00000 /* bootboot struct virtual address */
#define BOOTBOOT_ENV 0xffffffffffe01000 /* environment string virtual address */
#define BOOTBOOT_CORE 0xffffffffffe02000 /* core loadable segment start */
/* minimum protocol level:
* hardcoded kernel name, static kernel memory addresses */
#define PROTOCOL_MINIMAL 0
/* static protocol level:
* kernel name parsed from environment, static kernel memory addresses */
#define PROTOCOL_STATIC 1
/* dynamic protocol level:
* kernel name parsed, kernel memory addresses from ELF or PE symbols */
#define PROTOCOL_DYNAMIC 2
/* big-endian flag */
#define PROTOCOL_BIGENDIAN 0x80
/* loader types, just informational */
#define LOADER_BIOS (0<<2)
#define LOADER_UEFI (1<<2)
#define LOADER_RPI (2<<2)
#define LOADER_COREBOOT (3<<2)
/* framebuffer pixel format, only 32 bits supported */
#define FB_ARGB 0
#define FB_RGBA 1
#define FB_ABGR 2
#define FB_BGRA 3
/* mmap entry, type is stored in least significant tetrad (half byte) of size
* this means size described in 16 byte units (not a problem, most modern
* firmware report memory in pages, 4096 byte units anyway). */
typedef struct {
uint64_t ptr;
uint64_t size;
} _pack MMapEnt;
#define MMapEnt_Ptr(a) ((a)->ptr)
#define MMapEnt_Size(a) ((a)->size & 0xFFFFFFFFFFFFFFF0)
#define MMapEnt_Type(a) ((a)->size & 0xF)
#define MMapEnt_IsFree(a) (((a)->size&0xF)==1)
#define MMAP_USED 0 /* don't use. Reserved or unknown regions */
#define MMAP_FREE 1 /* usable memory */
#define MMAP_ACPI 2 /* acpi memory, volatile and non-volatile as well */
#define MMAP_MMIO 3 /* memory mapped IO region */
#define INITRD_MAXSIZE 16 /* Mb */
typedef struct {
/* first 64 bytes is platform independent */
uint8_t magic[4]; /* 'BOOT' magic */
uint32_t size; /* length of bootboot structure, minimum 128 */
uint8_t protocol; /* 1, static addresses, see PROTOCOL_* and LOADER_* above */
uint8_t fb_type; /* framebuffer type, see FB_* above */
uint16_t numcores; /* number of processor cores */
uint16_t bspid; /* Bootsrap processor ID (Local APIC Id on x86_64) */
int16_t timezone; /* in minutes -1440..1440 */
uint8_t datetime[8]; /* in BCD yyyymmddhhiiss UTC (independent to timezone) */
uint64_t initrd_ptr; /* ramdisk image position and size */
uint64_t initrd_size;
uint64_t fb_ptr; /* framebuffer pointer and dimensions */
uint32_t fb_size;
uint32_t fb_width;
uint32_t fb_height;
uint32_t fb_scanline;
/* the rest (64 bytes) is platform specific */
union {
struct {
uint64_t acpi_ptr;
uint64_t smbi_ptr;
uint64_t efi_ptr;
uint64_t mp_ptr;
uint64_t unused0;
uint64_t unused1;
uint64_t unused2;
uint64_t unused3;
} x86_64;
struct {
uint64_t acpi_ptr;
uint64_t mmio_ptr;
uint64_t efi_ptr;
uint64_t unused0;
uint64_t unused1;
uint64_t unused2;
uint64_t unused3;
uint64_t unused4;
} aarch64;
} arch;
/* from 128th byte, MMapEnt[], more records may follow */
MMapEnt mmap;
/* use like this:
* MMapEnt *mmap_ent = &bootboot.mmap; mmap_ent++;
* until you reach bootboot->size, while(mmap_ent < bootboot + bootboot->size) */
} _pack BOOTBOOT;
#ifdef _MSC_VER
#pragma pack(pop)
#endif
#ifdef __cplusplus
}
#endif
#endif

126
lboot.S
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@ -4,6 +4,7 @@
.text
.code16
// _start: entry point
_start: cli
cld
@ -24,14 +25,20 @@ _start: cli
call print
call unreal
mov $msg_memmap, %si
mov $msg_getmap, %si
call print
call memmap
call getmap
mov $msg_paging, %si
call print
call paging
mov $msg_fin, %si
call print
1: hlt
jmp 1b
// hang: sleep indefinitely
hang: hlt
jmp hang
.set COM1, 0x3F8
.macro com1_write offset=0, byte
@ -40,6 +47,7 @@ _start: cli
outb %al, %dx
.endm
// init_com1: Set up COM1 port for debug output
init_com1: com1_write 1, 0x00 // clear interrupts
com1_write 3, 0x80 // set DLAB to 1
com1_write 0, 0x0C // 9600 baud rate
@ -47,67 +55,124 @@ init_com1: com1_write 1, 0x00 // clear interrupts
com1_write 3, 0x07 // 8 bit data + 1 parity bit
ret
// enable_a20: Allow use of 'high' memory
enable_a20: // TODO more thorough implementation
inb $0x92, %al
or $2, %al
outb %al, $0x92
ret
// unreal: Enter unreal mode
unreal: push %ds
lgdt gdt_ptr
mov %cr0, %eax
or $0x01, %al
mov %eax, %cr0
ljmp $0x8, $1f
ljmp $0x8, $_prot
1: mov $0x10, %cx
_prot: mov $0x10, %cx
mov %cx, %ds
and $0xFE, %al
mov %eax, %cr0
ljmp $0x0, $2f
ljmp $0x0, $_unreal
2: pop %ds
_unreal: pop %ds
ret
memmap: push %bp
mov %sp, %bp
sub $24, %sp
mov %ss, %ax
// getmap: Retrieve memory map using e820 BIOS function
getmap: mov %ds, %ax
mov %ax, %es
mov %sp, %di
mov $memmap, %di
xor %ebx, %ebx
mov $0x534D4150, %edx
mov $0x534D4150, %edx // e820 magic number
_nextmap: movl $0, 20(%di)
mov $24, %ecx
mov $0xE820, %eax
int $0x15
mov %bp, %sp
pop %bp
jc _endmap
test %ebx, %ebx
jz _endmap
add $24, %di
jmp _nextmap
_endmap: add $24, %di
mov %di, memmap_end
ret
// paging: Set up initial page tables for long mode
paging:
mov $4*4096, %ecx
call alloc
mov %eax, pd_ptr
mov $4096, %ecx
call alloc
mov %eax, pdp_ptr
mov $4096, %ecx
call alloc
mov %eax, pml4_ptr
mov pd_ptr, %edi
xor %ecx, %ecx
_pgnext: mov %ecx, %eax
shl $21, %eax
or $0b110000111, %eax
movl %eax, 0(%edi)
//movl %eax, 0(%edi,%ecx,8)
//movl $0, 4(%edi,%ecx,8)
inc %ecx
cmp $4*512, %ecx
jne _pgnext
//mov pml4_ptr, %edi
//movl 0(%edi)
//movl $0, 4(%edi)
ret
// alloc: take ECX bytes from usable space in memmap
// No realignment is performed, so only alloc aligned sizes.
alloc: mov $memmap-24, %si
_anext: add $24, %si
cmp memmap_end, %si // ran over end of memmap?
jae _aerr
cmpl $1, 16(%si)
jne _anext
// TODO check that entry has enough space
cmpl $0, 4(%si) // memory is above 4Gb?
jne _aerr
mov 0(%si), %eax
addl %ecx, 0(%si)
adcl $0, 4(%si)
subl %ecx, 8(%si)
sbbl $0, 12(%si)
ret
_aerr: mov $msg_aerr, %si
call print
jmp hang
// print: print NUL-terminated string pointed to by SI
print: xor %bx, %bx
1: mov $COM1+5, %dx
_nextchr: mov $COM1+5, %dx
inb %dx, %al
test $0x20, %al
jz 1b
jz _nextchr
lodsb
or %al, %al
jz 2f
jz _endprint
mov $COM1, %dx
outb %al, %dx
mov $0x0E, %ah
int $0x10
jmp 1b
jmp _nextchr
2: ret
_endprint: ret
// gdt: Protected mode / Unreal mode 16-bit GDT
gdt: // entry 0: null descriptor
.word 0
.word 0
@ -133,8 +198,21 @@ gdt: // entry 0: null descriptor
gdt_ptr: .word gdt_size-1
.long gdt
// Messages to print
msg_start: .asciz "Netboot via fernlader v1 ...\r\n"
msg_a20: .asciz " * Enabling A20\r\n"
msg_unreal: .asciz " * Unreal Mode\r\n"
msg_memmap: .asciz " * Fetching Memory Map\r\n"
msg_getmap: .asciz " * Memory Map\r\n"
msg_paging: .asciz " * Paging\r\n"
msg_fin: .asciz "Finished.\r\n"
msg_aerr: .asciz "panic: Unable to allocate memory.\r\n"
// Long mode initial page tables
pd_ptr: .long 0
pdp_ptr: .long 0
pml4_ptr: .long 0
// Memory map area
memmap_end: .word 0
.align 8
memmap: // begins at end of binary

2
run-qemu.sh
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@ -1,2 +1,2 @@
#!/bin/sh
qemu-system-x86_64 -netdev user,id=n1,net=10.0.0.5/24,tftp=netboot,bootfile=/boot.bin -device virtio-net-pci,netdev=n1
qemu-system-x86_64 -netdev user,id=n1,net=10.0.0.5/24,tftp=.,bootfile=/boot.bin -device virtio-net-pci,netdev=n1,bootindex=0 "$@"