diff options
| -rw-r--r-- | NEWS | 6 | ||||
| -rw-r--r-- | TODO | 7 | ||||
| -rw-r--r-- | ldlinux.asm | 235 | ||||
| -rw-r--r-- | version | 2 |
4 files changed, 225 insertions, 25 deletions
@@ -1,3 +1,9 @@ +Changes in 1.37: + * Fix a bug that caused "label" statements in syslinux.cfg to + not be handled properly. + * Updated the documentation. Among other things, we now allow + up to 128 "label" statements. + Changes in 1.36: * Fix for booting old (pre-initrd) kernels. * It seems at least some versions of OS/2 doesn't set up all @@ -1,13 +1,6 @@ -Currently scheduled for inclusion in 1.40: - -- "Comboot" style boot files. -- Booting DOS for a DOS/Linux dual rescue disk. - Cleaned up documentation, with a real man page. - Boot ELKS, if at all possible (may have problems with i386 assumption.) - -For a later release, perhaps: - - Support for clusters larger than 16K. This would require changing a lot of the SYSLINUX internals so we can read partial clusters; change the current "cluster pointers" to become diff --git a/ldlinux.asm b/ldlinux.asm index c05c5eab..47d16662 100644 --- a/ldlinux.asm +++ b/ldlinux.asm @@ -138,7 +138,8 @@ vk_end: equ $ ; Should be <= vk_size ; vk_seg equ 8000h ; This is where we stick'em xfer_buf_seg equ 7000h ; Bounce buffer for I/O to high mem -fat_seg equ 1000h ; 128K area for FAT (2x64K) +fat_seg equ 5000h ; 128K area for FAT (2x64K) +comboot_seg equ 1000h ; COMBOOT image loading zone ; ; For our convenience: define macros for jump-over-unconditinal jumps @@ -302,6 +303,8 @@ NumBufEnd equ NumBuf+15 ; Pointer to last byte in NumBuf alignb 4 InitRDat resd 1 ; Load address (linear) for initrd HiLoadAddr resd 1 ; Address pointer for high load loop +KernelName resb 12 ; Mangled name for kernel + ; (note the spare byte after!) RootDir equ $ ; Location of root directory RootDir1 resw 1 RootDir2 resw 1 @@ -336,6 +339,7 @@ KernelCNameLen resw 1 ; Length of unmangled kernel name InitRDCNameLen resw 1 ; Length of unmangled initrd name NextCharJump resw 1 ; Routine to interpret next print char SetupSecs resw 1 ; Number of setup sectors +SavedSP resw 1 ; Our SP while running a COMBOOT image TextAttrBX equ $ TextAttribute resb 1 ; Text attribute for message file TextPage resb 1 ; Active display page @@ -349,7 +353,6 @@ RetryCount resb 1 ; Used for disk access retries KbdFlags resb 1 ; Check for keyboard escapes LoadFlags resb 1 ; Loadflags from kernel MNameBuf resb 11 ; Generic mangled file name buffer -KernelName resb 11 ; Mangled name for kernel InitRD resb 11 ; initrd= mangled name KernelCName resb 13 ; Unmangled kernel name InitRDCName resb 13 ; Unmangled initrd name @@ -364,6 +367,7 @@ bootsec equ $ ; loaded and ready for us ; bsOemName db 'SYSLINUX' ; The SYS command sets this, so... +superblock equ $ bsBytesPerSec zw 1 bsSecPerClust zb 1 bsResSectors zw 1 @@ -386,12 +390,13 @@ bsBootSignature zb 1 ; 29h if the following fields exist bsVolumeID zd 1 bsVolumeLabel zb 11 bsFileSysType zb 8 ; Must be FAT12 for this version +superblock_len equ $-superblock ; ; Note we don't check the constraints above now; we did that at install ; time (we hope!) ; -floppy_table equ $ ; No sense in wasting memory, overwrite start +;floppy_table equ $ ; No sense in wasting memory, overwrite start start: cli ; No interrupts yet, please @@ -1462,7 +1467,7 @@ clin_opt_ptr: dec si ; Point to first nonblank vk_check: pusha mov cx,11 repe cmpsb ; Is this it? - je vk_found + je near vk_found popa add si,vk_size loop vk_check @@ -1485,17 +1490,26 @@ not_vk: pop ds pop di pop si pop es + mov bx,exten_count << 2 ; Alternates to try ; ; Find the kernel on disk ; -get_kernel: mov si,KernelName +get_kernel: mov eax,[KernelName+8] ; Save initial extension + mov [OrigKernelExt],eax +.search_loop: push bx + mov si,KernelName mov di,KernelCName call unmangle_name ; Get human form sub di,KernelCName mov [KernelCNameLen],di - mov di,KernelName ; Search on disk + mov di,KernelName ; Search on disk call searchdir + pop bx jnz kernel_good + mov eax,[exten_table+bx] ; Try a different extension + mov [KernelName+8],eax + sub bx,byte 4 + jnb .search_loop bad_kernel: mov si,err_notfound ; Complain about missing kernel call writestr mov si,KernelCName @@ -1531,19 +1545,41 @@ vk_found: popa pop di ; DI -> KernelName push di mov si,VKernelBuf+vk_rname - mov cx,11 + mov cx,11 ; We need ECX == CX later rep movsb pop di - jmp short get_kernel + xor bx,bx ; Try only one version + jmp get_kernel ; ; kernel_corrupt: Called if the kernel file does not seem healthy ; kernel_corrupt: mov si,err_notkernel jmp abort_load -kernel_good: ; ; This is it! We have a name (and location on the disk)... let's load -; that sucker!! +; that sucker!! First we have to decide what kind of file this is; base +; that decision on the file extension. The following extensions are +; recognized: +; +; .COM - COMBOOT image +; .CBT - COMBOOT image +; .BS - Boot sector +; .BSS - Boot sector, but transfer over DOS superblock +; +; Anything else is assumed to be a Linux kernel. +; +kernel_good: + mov ecx,[KernelName+8] ; Get (mangled) extension + and ecx,00ffffffh ; 3 bytes + cmp ecx,'COM' + je near is_comboot_image + cmp ecx,'CBT' + je near is_comboot_image + cmp ecx,'BS ' + je near is_bootsector + cmp ecx,'BSS' + je near is_bss_sector + ; Otherwise Linux kernel ; ; A Linux kernel consists of three parts: boot sector, setup code, and ; kernel code. The boot sector is never executed when using an external @@ -1563,7 +1599,7 @@ kernel_good: ; First check that our kernel is at least 64K and less than 8M (if it is ; more than 8M, we need to change the logic for loading it anyway...) ; -load_it: +is_linux_kernel: cmp dx,80h ; 8 megs ja kernel_corrupt and dx,dx @@ -1616,9 +1652,9 @@ kernel_sane: push ax xor bx,bx pop si ; Cluster pointer on stack call getfssec - jc kernel_corrupt ; Failure in first 32K + jc near kernel_corrupt ; Failure in first 32K cmp word [es:bs_bootsign],0AA55h - jne kernel_corrupt ; Boot sec signature missing + jne near kernel_corrupt ; Boot sec signature missing ; ; Get the BIOS' idea of what the size of high memory is ; @@ -1972,6 +2008,148 @@ load_old_kernel: mov word [SetupSecs],4 ; Always 4 setup sectors mov byte [LoadFlags],0 ; Always low jmp read_kernel + +; +; Load a COMBOOT image. A COMBOOT image is basically a DOS .COM file, +; except that it may, of course, not contain any DOS system calls. We +; do, however, allow the execution of INT 20h to return to SYSLINUX. +; +is_comboot_image: + and dx,dx + jnz comboot_too_large + cmp ax,0ff00h ; Max size in bytes + jae comboot_too_large + + ; + ; Set up the DOS vectors in the IVT (INT 20h-3fh) + ; + mov dword [4*0x20],comboot_return ; INT 20h vector + mov eax,comboot_bogus + mov di,4*0x21 + mov cx,31 ; All remaining DOS vectors + rep stosd + + mov cx,comboot_seg + mov es,cx + + mov bx,100h ; Load at <seg>:0100h + + mov cx,[ClustPerMoby] ; Absolute maximum # of clusters + call getfssec + + xor di,di + mov cx,64 ; 256 bytes (size of PSP) + xor eax,eax ; Clear PSP + rep stosd + + mov word [es:0], 020CDh ; INT 20h instruction + + ; Copy the command line from high memory + mov cx,125 ; Max cmdline len (minus space and CR) + mov si,[CmdOptPtr] + mov di,081h ; Offset in PSP for command line + mov al,' ' ; DOS command lines begin with a space + stosb + +comboot_cmd_cp: lodsb + and al,al + jz comboot_end_cmd + stosb + loop comboot_cmd_cp +comboot_end_cmd: mov al,0Dh ; CR after last character + stosb + mov al,126 ; Include space but not CR + sub al,cl + mov [es:80h], al ; Store command line length + + mov ax,es + mov ds,ax + mov ss,ax + xor sp,sp + push word 0 ; Return to address 0 -> exit + + jmp comboot_seg:100h ; Run it + +; Looks like a COMBOOT image but too large +comboot_too_large: + mov si,err_comlarge + call writestr +cb_enter: jmp enter_command + +; Proper return vector +comboot_return: cli ; Don't trust anyone + xor ax,ax + mov ss,ax + mov sp,[ss:SavedSP] + mov ds,ax + mov es,ax + sti + jmp short cb_enter + +; Attempted to execute DOS system call +comboot_bogus: cli ; Don't trust anyone + xor ax,ax + mov ss,ax + mov sp,[ss:SavedSP] + mov ds,ax + mov es,ax + sti + mov si,KernelCName + call writestr + mov si,err_notdos + call writestr + jmp short cb_enter + +; +; Load a boot sector +; +is_bootsector: + ; Transfer zero bytes + push word 0 + jmp short load_bootsec +is_bss_sector: + ; Transfer the superblock + push word superblock_len +load_bootsec: + and dx,dx + jnz bad_bootsec + cmp ax,[bsBytesPerSec] + jne bad_bootsec + + mov bx,trackbuf + mov cx,1 ; 1 cluster >= 1 sector + call getfssec + + mov bx,[bsBytesPerSec] + mov ax,[bx+trackbuf-2] + cmp ax,0AA55h ; Boot sector signature + jne bad_bootsec + + mov si,superblock + mov di,trackbuf+(superblock-bootsec) + pop cx ; Transfer count + rep movsb +; +; Okay, here we go... copy over our own boot sector and run the new one +; + cli ; Point of no return + + mov dl,[bsDriveNumber] ; May not be in new bootsector! + + mov si,trackbuf + mov di,bootsec + mov cx,[bsBytesPerSec] + rep movsb + + xor si,si ; BUG: should point to partition info + + jmp bootsec + +bad_bootsec: + mov si,err_bootsec + call writestr + jmp enter_command + ; ; cwritestr: write a null-terminated string to the console, saving ; registers on entry (we can't use this in the boot sector, @@ -2063,10 +2241,16 @@ bcopy: ret ; -; Routines to enable and disable (yuck) A20 -; These routines are largely cut-and-paste from the Linux setup code +; Routines to enable and disable (yuck) A20. These routines are gathered +; from tips from a couple of sources, including the Linux kernel and +; http://www.x86.org/. The need for the delay to be as large as given here +; is indicated by Donnie Barnes of RedHat, the problematic system being an +; IBM ThinkPad 760EL. +; +; We typically toggle A20 twice for every 64K transferred. ; -%define io_delay out 0EDh, ax ; Invalid port (we hope) +%define io_delay out 080h,al ; Invalid port (we hope) +%define delaytime 1024 ; ISA bus cycles (1.5 µs) enable_a20: call empty_8042 @@ -3014,7 +3198,7 @@ copyright_str db ' Copyright (C) 1994-', year, ' H. Peter Anvin' boot_prompt db 'boot: ',0 wipe_char db 08h, ' ', 08h, 0 err_notfound db 'Could not find kernel image: ',0 -err_notkernel db 0Dh, 0Ah, 'Invalid or corrupt kernel image: ', 0 +err_notkernel db 0Dh, 0Ah, 'Invalid or corrupt kernel image.', 0Dh, 0Ah, 0 err_not386 db 'It appears your computer uses a 286 or lower CPU.' db 0Dh, 0Ah db 'You cannot run Linux unless you have a 386 or higher CPU' @@ -3038,6 +3222,9 @@ err_nohighmem db 'Not enough memory to load specified kernel.', 0Dh, 0Ah, 0 err_highload db 0Dh, 0Ah, 'Kernel transfer failure.', 0Dh, 0Ah, 0 err_oldkernel db 'Cannot load a ramdisk with an old kernel image.' db 0Dh, 0Ah, 0 +err_notdos db ': attempted DOS system call', 0Dh, 0Ah, 0 +err_comlarge db 'COMBOOT image too large.', 0Dh, 0Ah, 0 +err_bootsec db 'Invalid or corrupt boot sector image.', 0Dh, 0Ah, 0 loading_msg db 'Loading ', 0 dotdot_msg db '.' dot_msg db '.', 0 @@ -3076,6 +3263,20 @@ keywd_table db 'ap' ; append db 'f0' ; F10 dw 0 ; +; Extensions to search for (in *reverse* order). Note that the last +; (lexically first) entry in the table is a placeholder for the original +; extension, needed for error messages. The exten_table is shifted so +; the table is 1-based; this is because a "loop" cx is used as index. +; +exten_table: +OrigKernelExt: dd 0 ; Original extension + db 'COM',0 ; COMBOOT (same as DOS) + db 'BS ',0 ; Boot Sector + db 'BSS',0 ; Boot Sector (add superblock) + db 'CBT',0 ; COMBOOT (specific) + +exten_count equ (($-exten_table) >> 2) - 1 ; Number of alternates +; ; Misc initialized (data) variables ; AppendLen dw 0 ; Bytes in append= command @@ -1 +1 @@ -1.37 +1.40 |