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https://gitlab.com/bztsrc/bootboot.git
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Load initrd as Grub module
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bzt
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4 changed files with 54 additions and 9 deletions
BIN
bootboot.bin
BIN
bootboot.bin
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@ -5,7 +5,7 @@ See [BOOTBOOT Protocol](https://gitlab.com/bztsrc/bootboot) for common details.
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On [BIOS](http://www.scs.stanford.edu/05au-cs240c/lab/specsbbs101.pdf) based systems, the same image can be loaded via
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[Multiboot](https://www.gnu.org/software/grub/manual/multiboot/multiboot.html),
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chainload from MBR or VBR (GPT hybrid booting) or run as a BIOS Expansion ROM
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chainload from MBR or VBR (GPT hybrid booting via __boot.bin__) or run as a BIOS Expansion ROM
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(so not only the ramdisk can be in ROM, but the loader as well).
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Machine state
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@ -24,7 +24,17 @@ Installation
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2. *BIOS ROM*: install __bootboot.bin__ in a **_BIOS Expansion ROM_**.
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3. *GRUB*: specify __bootboot.bin__ as "kernel" in grub.cfg, or you can chainload __boot.bin__.
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3. *GRUB*: specify __bootboot.bin__ as a Multiboot "kernel" in grub.cfg, or you can also chainload __boot.bin__. You can load
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the initrd and the environment file as modules, if not given, they will be loaded from disk as usual. Example:
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```
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menuentry "MyKernel" {
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multiboot /bootboot/loader # bootboot.bin
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module /bootboot/initrd # first module is the initrd (optional)
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module /bootboot/config # second module is the environment file (optional)
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boot
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}
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```
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Limitations
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-----------
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@ -178,7 +178,7 @@ loader: db 55h,0AAh ;ROM magic
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.pnpptr: dw 0
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.flags: dd 0
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MB_MAGIC equ 01BADB002h
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MB_FLAGS equ 0D43h
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MB_FLAGS equ 010001h
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align 8
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.mb_header: dd MB_MAGIC ;magic
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dd MB_FLAGS ;flags
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@ -200,19 +200,46 @@ MB_FLAGS equ 0D43h
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multiboot_start:
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cld
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cli
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xor dl, dl
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;clear drive code, initrd ptr and environment
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xor edx, edx
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mov edi, 9000h
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mov dword [edi], edx
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mov dword [bootboot.initrd_ptr], edx
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mov dword [bootboot.initrd_size], edx
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;no GRUB environment available?
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cmp eax, 2BADB002h
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jne @f
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;save drive code for boot device
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mov dl, byte [ebx+12]
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;is there a module? mod_count!=0
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cmp dword [ebx+20], 0
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jz @f
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;mod_addr!=0
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mov eax, dword [ebx+24]
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or eax, eax
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jz @f
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;mods[0].end
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mov ecx, dword [eax+4]
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sub ecx, dword [eax]
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mov dword [bootboot.initrd_size], ecx
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;mods[0].start
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mov ecx, dword [eax]
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mov dword [bootboot.initrd_ptr], ecx
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inc byte [hasinitrd]
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;mod_count>1?
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cmp dword [ebx+20], 1
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jbe @f
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;mods[1], copy environment (4k)
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mov esi, dword [eax+16]
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mov ecx, 1024
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repnz movsd
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@@: jmp CODE_BOOT:.real ;load 16 bit mode segment into cs
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USE16
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.real: mov eax, CR0
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and al, 0FEh ;switching back to real mode
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mov CR0, eax
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xor ax, ax
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mov ds, ax ;load registers 2nd turn
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mov ds, ax ;load segment registers
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mov es, ax
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mov ss, ax
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jmp 0:realmode_start
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@ -388,9 +415,15 @@ getmemmap:
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DBG dbg_mem
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xor eax, eax
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mov dword [bootboot.acpi_ptr], eax
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mov dword [bootboot.smbi_ptr], eax
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mov edi, bootboot.acpi_ptr
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mov ecx, 16
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repnz stosd
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cmp byte [hasinitrd], 0
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jnz @f
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mov dword [bootboot.initrd_ptr], eax
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mov dword [bootboot.initrd_size], eax
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@@: mov dword [bootboot.initrd_ptr+4], eax
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mov dword [bootboot.initrd_size+4], eax
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mov eax, bootboot_MAGIC
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mov dword [bootboot.magic], eax
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mov dword [bootboot.size], 128
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@ -828,6 +861,8 @@ protmode_start:
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mov esp, 7C00h
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; ------- Locate initrd --------
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cmp byte [hasinitrd], 0
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jnz .initrdrom
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mov esi, 0C8000h
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.nextrom: cmp word [esi], 0AA55h
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jne @f
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@ -1056,7 +1091,7 @@ protmode_start:
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jne .notcfg
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cmp dword [esi+7], ' '
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jne .notcfg
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; load environment from FS0:/BOOTBOOT/CONFIG
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push edx
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push esi
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push edi
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@ -1864,7 +1899,6 @@ core_ptr: dd 0
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core_len: dd 0
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ebdaptr: dd 0
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hw_stack: dd 0
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lastmsg: dd 0
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bpb_sec: dd 0 ;ESP's first sector
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root_sec: dd 0 ;root directory's first sector
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data_sec: dd 0 ;first data sector
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@ -1882,6 +1916,7 @@ lbapacket: ;lba packet for BIOS
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reqwidth: dd 1024
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reqheight: dd 768
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bootdev: db 0
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hasinitrd: db 0
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fattype: db 0
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vbememsize: dw 0
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bkp: dd ' '
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