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enable framebuffer with multiboot2 and reserve frambuffer memory in pmm #8

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52 changes: 28 additions & 24 deletions arch/x86_64/boot.asm
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Original file line number Diff line number Diff line change
@@ -1,4 +1,3 @@

section .multiboot2
bits 32

Expand All @@ -13,6 +12,20 @@ mb2_start:
dd MB2_ARCH
dd MB2_LEN
dd MB2_CHECKSUM

; ---- framebuffer tag ----
align 8
fb_tag_start:
dw 5 ; type = 5 (framebuffer)
dw 0 ; flags = 0 (required)
dd fb_tag_end - fb_tag_start ; size = کل تگ (20 بایت)
dd 1024 ; width
dd 768 ; height
dd 32 ; depth
fb_tag_end:

; ---- end tag ----
align 8
dw 0
dw 0
dd 8
Expand Down Expand Up @@ -279,11 +292,9 @@ section .text

global syscall_asm_entry
syscall_asm_entry:

; Capture user state BEFORE any stack changes — fork() reads these
mov [user_ctx_rip], rcx ; user RIP (SYSCALL saves RIP → RCX)
mov [user_ctx_rflags], r11 ; user RFLAGS (SYSCALL saves RFLAGS → R11)
mov [user_ctx_rsp], rsp ; user RSP (unchanged at SYSCALL entry)
mov [user_ctx_rip], rcx
mov [user_ctx_rflags], r11
mov [user_ctx_rsp], rsp

push rcx
push r11
Expand All @@ -298,36 +309,29 @@ syscall_asm_entry:
pop rcx
o64 sysret

; ── fork child trampoline ───────────────────────────────────────────
; Called by arch_switch when the forked child is first scheduled.
; arch_switch restores: r15, r14, r13, r12, rbp, rbx
; We encode: r12 = user RIP
; r13 = user RSP
; r14 = user RFLAGS
global fork_child_stub
fork_child_stub:
mov ax, 0x23 ; restore user data segments
mov ax, 0x23
mov ds, ax
mov es, ax
xor rax, rax ; child returns 0 from fork()
mov rcx, r12 ; user RIP → sysretq reads rcx
mov r11, r14 ; user RFLAGS → sysretq reads r11
mov rsp, r13 ; switch back to user stack (pre-syscall RSP)
xor rax, rax
mov rcx, r12
mov r11, r14
mov rsp, r13
o64 sysret

global _enter_usermode
_enter_usermode:
cli

mov ax, 0x23
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax

push qword 0x23 ; SS (user data selector | RPL3)
push rsi ; RSP (user stack)
push qword 0x202 ; RFLAGS (IF=1, reserved bit 1)
push qword 0x1B ; CS (user code selector | RPL3)
push rdi ; RIP (entry point)
iretq
push qword 0x23
push rsi
push qword 0x202
push qword 0x1B
push rdi
iretq
41 changes: 36 additions & 5 deletions mm/pmm.c
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Original file line number Diff line number Diff line change
@@ -1,12 +1,12 @@

#include "pmm.h"
#include "../lib/string.h"
#include <stdint.h>
#include <stdbool.h>

#define MB2_MAGIC_VAL 0x36D76289u
#define TAG_END 0u
#define TAG_MMAP 6u
#define MB2_MAGIC_VAL 0x36D76289u
#define TAG_END 0u
#define TAG_MMAP 6u
#define TAG_FRAMEBUFFER 8u

typedef struct __attribute__((packed)) { uint32_t total, reserved; } mb2_hdr_t;
typedef struct __attribute__((packed)) { uint32_t type, size; } mb2_tag_t;
Expand All @@ -17,6 +17,16 @@ typedef struct __attribute__((packed)) {
uint64_t base, len;
uint32_t type, _res;
} mb2_mmap_entry_t;
typedef struct __attribute__((packed)) {
uint32_t type, size;
uint64_t fb_addr;
uint32_t fb_pitch;
uint32_t fb_width;
uint32_t fb_height;
uint8_t fb_bpp;
uint8_t fb_type;
uint16_t reserved;
} mb2_fb_tag_t;

#define BITMAP_MAX_PAGES (16 * 1024 * 1024)

Expand All @@ -25,6 +35,9 @@ static size_t total_pages = 0;
static size_t free_pages = 0;
static size_t bitmap_size = 0;

static uint64_t fb_addr = 0;
static uint64_t fb_len = 0;

static void bm_set (size_t idx) { bitmap[idx/8] |= (uint8_t)(1u << (idx%8)); }
static void bm_clear(size_t idx) { bitmap[idx/8] &= (uint8_t)~(1u << (idx%8)); }
static bool bm_test (size_t idx) { return (bitmap[idx/8] >> (idx%8)) & 1u; }
Expand Down Expand Up @@ -52,6 +65,12 @@ pmm_init(uint32_t magic, uint64_t info_addr)
if (e->type == 1 && top > max_addr) max_addr = top;
ep += mt->entry_size;
}
} else if (tag->type == TAG_FRAMEBUFFER) {
mb2_fb_tag_t *fb = (mb2_fb_tag_t *)ptr;
fb_addr = fb->fb_addr;
fb_len = (uint64_t)fb->fb_pitch * fb->fb_height;
uint64_t fb_top = fb_addr + fb_len;
if (fb_top > max_addr) max_addr = fb_top;
}
ptr += (tag->size + 7) & ~7u;
}
Expand Down Expand Up @@ -117,6 +136,18 @@ pmm_init(uint32_t magic, uint64_t info_addr)
free_pages--;
}
}

if (fb_addr != 0 && fb_len != 0) {
uint64_t start = fb_addr & ~(uint64_t)(PAGE_SIZE - 1);
uint64_t stop = (fb_addr + fb_len + PAGE_SIZE - 1) & ~(uint64_t)(PAGE_SIZE - 1);
for (uint64_t a = start; a < stop; a += PAGE_SIZE) {
size_t idx = (size_t)(a / PAGE_SIZE);
if (idx < total_pages && !bm_test(idx)) {
bm_set(idx);
free_pages--;
}
}
}
}

void *
Expand All @@ -143,4 +174,4 @@ pmm_free(void *page)
}

size_t pmm_free_pages(void) { return free_pages; }
size_t pmm_total_pages(void) { return total_pages; }
size_t pmm_total_pages(void) { return total_pages; }