diff options
| -rw-r--r-- | src/arch/i386/prefix/romprefix.S | 151 |
1 files changed, 107 insertions, 44 deletions
diff --git a/src/arch/i386/prefix/romprefix.S b/src/arch/i386/prefix/romprefix.S index f9b9e169..fbc8f00b 100644 --- a/src/arch/i386/prefix/romprefix.S +++ b/src/arch/i386/prefix/romprefix.S @@ -145,8 +145,6 @@ init: cld pushw %cs popw %ds - pushw $0x40 - popw %fs /* Shuffle some registers around. We need %di available for * the print_xxx functions, and in a register that's @@ -317,46 +315,17 @@ no_pmm: movw $init_message_prompt, %si xorw %di, %di call print_message - /* Empty the keyboard buffer before waiting for input */ -empty_keyboard_buffer: - movb $0x01, %ah - int $0x16 - jz 1f - xorw %ax, %ax - int $0x16 - jmp empty_keyboard_buffer -1: /* Wait for up to 3s for a key press */ - movw $(18 * 3), %cx /* Approx 3s worth of timer ticks */ -wait_for_key: - decw %cx - jz no_key_pressed - /* Wait for timer tick to be updated */ - movl %fs:(0x6c), %eax -1: pushf - sti - hlt - popf - cmpl %fs:(0x6c), %eax - je 1b - /* Check to see if a key was pressed */ - movb $0x01, %ah - int $0x16 - jz wait_for_key - /* Check to see if key was Ctrl-B */ - cmpb $0x02, %al - je 1f - /* Key was not Ctrl-B: remove from buffer and stop waiting */ - xorw %ax, %ax - int $0x16 - jmp no_key_pressed -1: /* Key was Ctrl-B: leave in keyboard buffer and invoke gPXE. - * The keypress will be picked up by the initial shell - * prompt, and we will drop into a shell. + /* Wait for Ctrl-B */ + movw $0xff02, %bx + call wait_for_key + jnz 1f + /* Ctrl-B was pressed: invoke gPXE. The keypress will be + * picked up by the initial shell prompt, and we will drop + * into a shell. */ pushw %cs call exec -no_key_pressed: - +1: /* Print blank lines to terminate messages */ movw $init_message_end, %si xorw %di, %di @@ -436,24 +405,54 @@ bev_entry: /* INT19 entry point * * Called via the hooked INT 19 if we detected a non-PnP BIOS. We - * attempt to return via the original INT 19 vector (if we were able to - * store it). + * attempt to return via the original INT 19 vector (if we were able + * to store it). */ int19_entry: pushw %cs + popw %ds + /* Prompt user to press B to boot */ + movw $int19_message_prompt, %si + xorw %di, %di + call print_message + movw $prodstr, %si + call print_message + movw $int19_message_dots, %si + call print_message + movw $0xdf42, %bx + call wait_for_key + jnz 1f + /* Leave keypress in buffer and start gPXE. The keypress will + * cause the usual initial Ctrl-B prompt to be skipped. + */ + pushw %cs call exec +1: /* Print blank lines to terminate messages */ + movw $int19_message_end, %si + xorw %di, %di + call print_message + /* Try to call original INT 19 vector */ movl %cs:orig_int19, %eax testl %eax, %eax - je 1f - /* Chain to original INT 19 vector */ + je 2f ljmp *%cs:orig_int19 -1: /* No chained vector: issue INT 18 as a last resort */ +2: /* No chained vector: issue INT 18 as a last resort */ int $0x18 .size int19_entry, . - int19_entry orig_int19: .long 0 .size orig_int19, . - orig_int19 +int19_message_prompt: + .asciz "Press B to boot from " + .size int19_message_prompt, . - int19_message_prompt +int19_message_dots: + .asciz "..." + .size int19_message_dots, . - int19_message_dots +int19_message_end: + .asciz "\n\n\n" + .size int19_message_end, . - int19_message_end + /* Execute as a boot device * */ @@ -560,3 +559,67 @@ undiloader: popl %esi lret .size undiloader, . - undiloader + +/* Wait for key press specified by %bl (masked by %bh) + * + * Used by init and INT19 code when prompting user. If the specified + * key is pressed, it is left in the keyboard buffer. + * + * Returns with ZF set iff specified key is pressed. + */ +wait_for_key: + /* Preserve registers */ + pushw %cx + pushw %ax +1: /* Empty the keyboard buffer before waiting for input */ + movb $0x01, %ah + int $0x16 + jz 2f + xorw %ax, %ax + int $0x16 + jmp 1b +2: /* Wait for up to 5s for a key press */ + movw $(18 * 5), %cx /* Approx 5s worth of timer ticks */ +3: decw %cx + js 99f /* Exit with ZF clear */ + /* Wait for timer tick to be updated */ + call wait_for_tick + /* Check to see if a key was pressed */ + movb $0x01, %ah + int $0x16 + jz 3b + /* Check to see if key was the specified key */ + andb %bh, %al + cmpb %al, %bl + je 99f /* Exit with ZF set */ + /* Not the specified key: remove from buffer and stop waiting */ + pushfw + xorw %ax, %ax + int $0x16 + popfw /* Exit with ZF clear */ +99: /* Restore registers and return */ + popw %ax + popw %cx + ret + .size wait_for_key, . - wait_for_key + +/* Wait for timer tick + * + * Used by wait_for_key + */ +wait_for_tick: + pushl %eax + pushw %fs + movw $0x40, %ax + movw %ax, %fs + movl %fs:(0x6c), %eax +1: pushf + sti + hlt + popf + cmpl %fs:(0x6c), %eax + je 1b + popw %fs + popl %eax + ret + .size wait_for_tick, . - wait_for_tick |