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> OS Construction > how to load kernel on my os |
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macomics 13 Nov 2024, 18:51
Already at the very beginning. You don't have jmp to your code, but immediately there is a field that should be 3 bytes further (just the place for jmp)
Code: jmp short startup nop OEM db "XPFAN316";, "9" ; 8 bytes bytes_sector dw 0x0200 sectors_cluster db 0x04 reserved dw 0x0001 fats db 0x02 root_entries dw 0x0200 sectors dw 0x0000 media_type db 0xf8 sectors_fat dw 0x0040 sectors_track dw 0x0020 heads dw 0x0040 sectors_hidden dd 0x00000000 sectors_large dd 0x00010000 drive_num db 0x00; dw 0x8000 ; byte current_head db 0x00; not used extended_sig db 0x29 serial dd 0x688b221b label db "MAYMAYOS ";, " " ; 11 bytes filesystem db "FAT16 "; , " "; 8 bytes startup: Here you jump to the kernel load address, but! Code: jmp 0x2000:0x0000 your kernel does not start with code, but with data (i.e. data will be executed)! Code: bits 16 org 0x0000 ; !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! welcome_text db "Welcome to MayMayOS$" old_int_off dw 0 old_int_seg dw 0 ; !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! mov ax,0x07e0 mov ds,ax mov es,ax Last edited by macomics on 13 Nov 2024, 19:11; edited 1 time in total |
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13 Nov 2024, 18:51 |
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xpfan3169 13 Nov 2024, 19:11
for some reason i got binary data of my floppy image
here is the corrected code incase boot.asm: Code: bits 16 org 100h jmp short startup nop OEM db "XPFAN316" bytes_sector dw 0x0200 sectors_cluster db 0x04 reserved dw 0x0001 fats db 0x02 root_entries dw 0x0200 sectors dw 0x0000 media_type db 0xf8 sectors_fat dw 0x0040 sectors_track dw 0x0020 heads dw 0x0040 sectors_hidden dd 0x00000000 sectors_large dd 0x00010000 drive_num dw 0x8000 extended_sig db 0x29 serial dd 0x688b221b label db "MAYMAYOS " filesystem db "FAT16 " startup: mov ax,0x07c0 mov ds,ax add ax,0x0020 mov ss,ax mov sp,0x1000 mov byte [boot_drive_num],dl mov ah,08h int 13h mov dl,dh mov dh,0 inc dl mov word [heads],dx mov ch,0 and ch,0x3f mov word [sectors_track],cx load_fat: mov si,msg_load call print_teletype mov ax,0x3000 mov es,ax mov bx,0x0000 mov ax,word [reserved] call calc_chs_ls mov ax,word [sectors_fat] mov ah,0x02 int 13h jnc load_root ;Load root if carry flag is not set jmp reboot ;Otherwise reboot load_root: mov si,msg_load call print_teletype mov ax,0x3800 mov es,ax call calc_root_start call calc_chs_ls mov ah,0x02 mov al,0x20 int 13h jnc search_init call reset_disk mov ah,0x02 mov al,0x20 int 13h jc reboot search_init: mov si,msg_search_root call print_teletype mov ax,0x07c0 mov ds,ax mov ax,0x3800 mov es,ax mov di,0x0000 mov cx,word [root_entries] check_entry: push cx mov cx,0x000b mov si,kern_filename push di repe cmpsb pop di pop cx je found_entry add di,0x0020 loop check_entry jmp reboot_fatal found_entry: mov ax,word [es:di+1ah] mov word [cluster],ax load_cluster: mov si,msg_load_cluster call print_teletype mov ax,word [cluster] sub ax,0x0002 mul byte [sectors_cluster] mov dx,ax call calc_root_start add ax,0x20 add ax,dx call calc_chs_ls mov ax,0x2000 mov es,ax mov bx,word [buffer_pointer] mov ah,0x02 mov al,byte [sectors_cluster] int 13h jnc next_cluster call reset_disk mov ah,0x02 mov al,byte [sectors_cluster] int 13h jc reboot next_cluster: mov ax,0x3000 mov ds,ax mov si,word [cluster] shl si,1 mov ax,word [ds:si] mov word [cluster],ax cmp ax,0xfff8 mov ax,0x0200 mul word [sectors_cluster] add word [buffer_pointer],ax jb load_cluster jump: mov si,msg_ready call print_teletype mov ah,0x00 int 16h mov dl,byte [boot_drive_num] jmp 0x2000:0x0000 calc_root_start: push dx mov ax,word [sectors_fat] mov dh,0x00 mov dl,byte [fats] mul dx add ax,word [reserved] pop dx ret calc_chs_ls: mov dx,0x0000 div word [sectors_track] mov cl,dl inc cl mov dx,0x0000 div word [heads] mov dh,dl mov ch,al mov dl,byte [boot_drive_num] ret print_teletype: lodsb cmp al,"$" je done_teletype mov ah,0eh int 10h jmp print_teletype done_teletype: ret reset_disk: push ax mov si,msg_retrying call print_teletype mov ah,0x00 mov dl,byte [boot_drive_num] int 13h jc reboot_fatal pop ax ret reboot_fatal: mov si,msg_fatal call print_teletype reboot: mov si,msg_reboot call print_teletype mov si,msg_ready call print_teletype mov ah,0x00 int 16h jmp 0xffff:0x0000 cluster dw 0x0000 buffer_pointer dw 0x0000 boot_drive_num db 0x00 msg_retrying db "Retry$" msg_fatal db "FATAL$" msg_reboot db "Reboot$" msg_search_root db "Search$" msg_load_cluster db "Load clstr$" msg_ready db "READY$" msg_load db "Press a key$" kern_filename db "KERNEL BIN" times 510-($-$$) db 0 dw 0xaa55 kernel.asm: Code: bits 16 org 0x2000 welcome_text db "Welcome to MayMayOS$" old_int_off dw 0 old_int_seg dw 0 mov si,welcome_text call print_teletype jmp set_ints print_teletype: lodsb cmp al,"$" je done_teletype mov ah,0eh int 10h jmp print_teletype done_teletype: ret set_ints: mov bx,[es:77h*4] mov [old_int_off],bx mov bx,[es:77h*4+2] mov [old_int_seg],bx mov dx,int_77_prog mov [es:77h*4],dx mov ax,cs mov [es:77h*4+2],ax jmp $ int_77_prog: pusha popa iret
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13 Nov 2024, 19:11 |
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macomics 13 Nov 2024, 19:28
Try this (with fasm-1.73.32 and qemu)
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13 Nov 2024, 19:28 |
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macomics 13 Nov 2024, 20:05
Screenshots
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13 Nov 2024, 20:05 |
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xpfan3169 14 Nov 2024, 09:20
k tkz i will try when i arrive home, btw should i use fat in mbr or kernel?
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14 Nov 2024, 09:20 |
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macomics 14 Nov 2024, 09:35
The concept of MBR/SBR/BS is closely related to the file system. It should work with the file system and load the first program from disk into memory, and then transfer control to it. You have declared the work with the file system yourself in your task list. Therefore, the kernel should also work with it.
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14 Nov 2024, 09:35 |
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Core i7 14 Nov 2024, 14:36
One note...
The int-10h interrupt handler has over 500 lines of code, so for printing text it is better to use direct output to the video buffer "rep stosw": Code: msg1 db 'Hello World!' len1 $ - msg1 ;..... mov ax,3 ; vmode = 80x25x16 int 10h mov cx,len1 mov si,msg1 mov ah,5 ; text color mov di,40 ; position in vBuff call printf ;..... printf: push es 0xb800 pop es @@: lodsb stosw loop @b pop es ret |
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14 Nov 2024, 14:36 |
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xpfan3169 14 Nov 2024, 15:19
i found this code from online and this code loads kernel into memory (i wanna use fat16 at the next sector after kernel)
boot.asm: Code: bits 16 org 0x7c00 cld xor ax,ax mov ss,ax mov sp,0x7c00 mov es,ax mov bx,0x7e00 mov ah,2 mov al,1 mov ch,0 mov cl,2 int 13h jmp 0x0000:0x7e00 times 510-($-$$) db 0 dw 0xaa55 kernel.asm: Code: bits 16 org 0x0000 mov ax,0x07e0 mov ds,ax mov es,ax |
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14 Nov 2024, 15:19 |
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macomics 14 Nov 2024, 15:27
@Core i7
Code: printf: push es ; you forgot xpfan3169 wrote: i found this code |
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14 Nov 2024, 15:27 |
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Core i7 14 Nov 2024, 16:35
@macomics no, there are 2 pushes in one line: push es 0xb800 --> pop es ... pop es
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14 Nov 2024, 16:35 |
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macomics 14 Nov 2024, 21:12
Core i7 wrote: @macomics no, there are 2 pushes in one line: push es 0xb800 --> pop es ... pop es |
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14 Nov 2024, 21:12 |
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Core i7 15 Nov 2024, 07:25
xpfan3169 wrote: which uses FAT16 file system. If your kernel does not have a file system manager, then you do not need to format the drive in FAT-16/32 - just read/write at the disk sector level. There are no interrupts among BIOS services that work with FS - only DOS int-25/26h. You should have other priorities - switching to protected mode with access to 4GB of memory, creating IDT/GDT tables, etc. To work with physical devices, you need access to PCI-Config-Space, and these are the highest memory addresses. If you want to leave BIOS interrupts, you can switch to "UnrealMode" to address all memory up to 4Gb. And there is nothing interesting in RMode with 1Mb of memory. |
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15 Nov 2024, 07:25 |
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xpfan3169 16 Nov 2024, 19:11
i found this code and i think i will use FAT12
Code: bits 16 org 0x7c00 jmp start nop OEM db "DISKNAME" BytesPerSect dw 512 SectPerCluster db 1 ReservedSects dw 1 NumberFATs db 2 TotalSects dw 2880 Media db 0x00 ;0x00 = number for floppy drive SectsPerFAT dw 9 SectsPerTrack dw 18 HeadsPerCylinder dw 2 dq 0 ;Hidden sectors DriveNumber db 0 Unused db 0 Bootsig db 0x29 Serial dd 0x1a2a3a VolumeLabel db "MAYMAYOS " FileSystem db "FAT12 " start: cli ;Clear interrupt flag (IF) mov ax,0x07c0 mov es,ax mov ds,ax mov gs,ax mov fs,ax xor ax,ax mov ss,ax mov sp,0xffff sti mov ax,19d mov cx,14d mov bx,200h call read_sects mov di,200h mov cx,224d find_file: push cx mov cx,11d mov si,filen push di repe cmpsb pop di je file_found pop cx add di,32 loop find_file int 18h file_found: pop cx mov dx,word [di+1ah] mov word [cluster],dx mov ax,1 mov cx,9 mov bx,200h call read_sects mov ax,60h mov es,ax xor bx,bx push bx cluster_loop: mov ax,word [cluster] sub ax,2 add ax,33d mov cx,1 pop bx call read_sects push bx mov ax,word [cluster] mov dx,ax mov cx,ax shr dx,1 add cx,dx mov bx,200h add bx,cx mov dx,word [bx] test ax,1 jnz odd_cluster and dx,0xffff jmp done odd_cluster: shr dx,4 done: mov word [cluster],dx cmp dx,0xff0 jb cluster_loop mov ax,es sub ax,10h mov es,ax mov ds,ax mov ss,ax xor sp,sp push es push 100h retf read_sects: mov di,5 sect_loop: push ax push bx push cx push dx call lbachs mov ah,02h mov al,1 mov dl,0 mov dh,[head] mov cl,[sector] mov ch,[track] int 13h jnc success xor ax,ax int 13h pop dx pop cx pop bx pop ax inc ax add bx,512d loop read_sects ret lbachs: pusha xor dx,dx mov cx,18d div cx inc dl mov byte [sector],dl mov cx,2 xor dx,dx div cx mov byte [head],dl mov byte [track],al popa ret cluster dw 0 sector db 0 head db 0 track db 0 filen db "KERNEL BIN" times 512-($-$$) db 0 dw 0xaa55 |
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16 Nov 2024, 19:11 |
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macomics 16 Nov 2024, 21:07
Do not stupidly take someone else's code (besides, I have already sent you 2 versions of the same in the archive). Then you will have to sort out the occupied memory blocks, and because of someone else's code, you will simply get confused in them.
Code: 00000 - 003FF = 00400: IFPT (Interrupt Far Pointers Table) 00400 - 005FF = 00200: BIOS vars 00600 - 9FFFF = 9FAFF: "Empty" (dirty) 9F000 - 9FFFF = 01000: (optional) BIOS reserved memory A0000 - AFFFF = 10000: Video memory (graphic) B0000 - B7FFF = 08000: Text video segment (old, hercules) B8000 - B8FFF = 01000: Text video segment (current, page 0) B9000 - B9FFF = 01000: Text video segment (page 1) BA000 - BAFFF = 01000: Text video segment (page 2) BB000 - BBFFF = 01000: Text video segment (page 3) BC000 - BCFFF = 01000: Text video segment (page 4) BD000 - BDFFF = 01000: Text video segment (page 5) BE000 - BEFFF = 01000: Text video segment (page 6) BF000 - BFFFF = 01000: Text video segment (page 7) C0000 - CFFFF = 10000: ROM BIOS (extended, devices) D0000 - EFFFF = 20000: "Empty" (reserved) F0000 - FFFFF = 10000: ROM BIOS (main) 100000 - 10FFEF = 0FFF0: HMA (A20 gate) ADD: For example, this is a memory card for an example from the archive (qemu). Code: 00000 - 003FF = 00400: IFPT (Interrupt Far Pointers Table) 00400 - 005FF = 00200: BIOS vars 00600 - 009FF = 00400: "Empty" (available, free) 00A00 - 969FF = 96000: BOOT.BIN (600 kb) 96A00 - 9BFFF = 055FF: "Empty" (available, free) 9C000 - 9FBFF = 03C00: Stack segment 9FC00 - 9FFFF = 00400: BIOS reserved memory A0000 - AFFFF = 10000: Video memory (graphic) B0000 - B7FFF = 08000: Text video segment (old, hercules) B8000 - B8FFF = 01000: Text video segment (current, page 0) B9000 - B9FFF = 01000: Text video segment (page 1) BA000 - BAFFF = 01000: Text video segment (page 2) BB000 - BBFFF = 01000: Text video segment (page 3) BC000 - BCFFF = 01000: Text video segment (page 4) BD000 - BDFFF = 01000: Text video segment (page 5) BE000 - BEFFF = 01000: Text video segment (page 6) BF000 - BFFFF = 01000: Text video segment (page 7) C0000 - CFFFF = 10000: ROM BIOS (extended, devices) D0000 - EFFFF = 20000: "Empty" (reserved) F0000 - FFFFF = 10000: ROM BIOS (main) 100000 - 10FFEF = 0FFF0: HMA (A20 gate) |
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16 Nov 2024, 21:07 |
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