diff options
| -rw-r--r-- | NEWS | 2 | ||||
| -rw-r--r-- | isolinux.asm | 58 |
2 files changed, 54 insertions, 6 deletions
@@ -16,6 +16,8 @@ Changes in 1.75: to guess the maximum transfer size. I am *hoping* this will cut down on the number of systems for which -s is required to work at any acceptable speed. + * ISOLINUX: Add a few more workarounds for various broken El + Torito BIOSes. Changes in 1.74: * SYSLINUX: fix bug that would cause valid kernel images to be diff --git a/isolinux.asm b/isolinux.asm index 807f707d..1b57a944 100644 --- a/isolinux.asm +++ b/isolinux.asm @@ -33,6 +33,7 @@ my_id equ isolinux_id FILENAME_MAX_LG2 equ 8 ; log2(Max filename size Including final null) FILENAME_MAX equ (1 << FILENAME_MAX_LG2) NULLFILE equ 0 ; Zero byte == null file name +retry_count equ 6 ; How patient are we wirh the BIOS? %assign HIGHMEM_SLOP 128*1024 ; Avoid this much memory near the top MAX_OPEN_LG2 equ 6 ; log2(Max number of open files) MAX_OPEN equ (1 << MAX_OPEN_LG2) @@ -173,6 +174,7 @@ PktTimeout resw 1 ; Timeout for current packet KernelExtPtr resw 1 ; During search, final null pointer LocalBootType resw 1 ; Local boot return code ImageSectors resw 1 ; isolinux.bin size, sectors +DiskSys resw 1 ; Last INT 13h call TextAttrBX equ $ TextAttribute resb 1 ; Text attribute for message file TextPage resb 1 ; Active display page @@ -434,6 +436,23 @@ spec_query_failed: cmp dl, 80h jnb .test_loop + ; No spec packet anywhere. Some particularly pathetic + ; BIOSes apparently don't even implement function + ; 4B01h, so we can't query a spec packet no matter + ; what. If we got a drive number in DL, then try to + ; use it, and if it works, then well... + mov dl,[DriveNo] + cmp dl,81h ; Should be 81-FF at least + jb fatal_error ; If not, it's hopeless + + ; Write a warning to indicate we're on *very* thin ice now + mov si,nospec_msg + call writemsg + mov al,dl + call writehex2 + call crlf + jmp .found_drive ; Pray that this works... + fatal_error: mov si,nothing_msg call writemsg @@ -498,9 +517,9 @@ getlinsec: mov [si+8],eax .loop: push bp ; Sectors left - cmp bp,byte 32 + cmp bp,[MaxTransfer] jbe .bp_ok - mov bp,32 + mov bp,[MaxTransfer] .bp_ok: mov [si+2],bp push si @@ -520,21 +539,45 @@ getlinsec: ret ; INT 13h with retry -xint13: mov byte [RetryCount], 6 +xint13: mov byte [RetryCount],retry_count .try: pushad int 13h jc .error add sp,byte 8*4 ; Clean up stack ret -.error: mov [DiskError],ah ; Save error code +.error: + mov [DiskError],ah ; Save error code popad + mov [DiskSys],ax ; Save system call number dec byte [RetryCount] - jnz .try + jz .real_error + push ax + mov al,[RetryCount] + mov ah,[dapa+2] ; Sector transfer count + cmp al,2 ; Only 2 attempts left + ja .nodanger + mov ah,1 ; Drop transfer size to 1 + jmp short .setsize +.nodanger: + cmp al,retry_count-2 + ja .again ; First time, just try again + shr ah,1 ; Otherwise, try to reduce + adc ah,0 ; the max transfer size, but not to 0 +.setsize: + mov [MaxTransfer],ah + mov [dapa+2],ah +.again: + pop ax + jmp .try .real_error: mov si,diskerr_msg call writemsg mov al,[DiskError] call writehex2 + mov si,oncall_str + call writestr + mov ax,[DiskSys] + call writehex4 mov si,ondrive_str call writestr mov al,dl @@ -590,8 +633,10 @@ allread_msg db 'Main image read, jumping to main code...', CR, LF, 0 spec_err_msg: db 'Loading spec packet failed, trying to wing it...', CR, LF, 0 maybe_msg: db 'Found something at drive = ', 0 alright_msg: db 'Looks like it might be right, continuing...', CR, LF, 0 +nospec_msg db 'Extremely broken BIOS detected, last ditch attempt with drive = ', 0 nosecsize_msg: db 'Failed to get sector size, assuming 0800', CR, LF, 0 diskerr_msg: db 'Disk error ', 0 +oncall_str: db ', AX = ',0 ondrive_str: db ', drive ', 0 nothing_msg: db 'Failed to locate CD-ROM device; boot failed.', CR, LF, 0 checkerr_msg: db 'Image checksum error, sorry...', CR, LF, 0 @@ -667,7 +712,8 @@ dapa: dw 16 ; Packet size dd 0 ; LBA (MSW) alignb 4, db 0 -Stack dw _start, 0 ; SS:SP for stack reset +Stack dw _start, 0 ; SS:SP for stack reset +MaxTransfer dw 32 ; Max sectors per transfer rl_checkpt equ $ ; Must be <= 800h |