diff options
Diffstat (limited to 'pxelinux.asm')
| -rw-r--r-- | pxelinux.asm | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/pxelinux.asm b/pxelinux.asm index 5a6976d9..85faf63e 100644 --- a/pxelinux.asm +++ b/pxelinux.asm @@ -1037,8 +1037,9 @@ pc_serial: call getint ; "serial" command cmp di,3 ja .port_is_io ; If port > 3 then port is I/O addr shl di,1 - mov di,[di+serial_base] -.port_is_io: mov [SerialPort],di + mov di,[di+serial_base] ; Get the I/O port from the BIOS +.port_is_io: + mov [SerialPort],di lea dx,[di+3] ; DX -> LCR mov al,83h ; Enable DLAB call slow_out @@ -1051,6 +1052,9 @@ pc_serial: call getint ; "serial" command mov al,03h ; Disable DLAB add dx,byte 2 ; DX -> LCR call slow_out + in al,dx ; Read back LCR (detect missing hw) + cmp al,03h ; If nothing here we'll read 00 or FF + jne .serial_port_bad ; Assume serial port busted sub dx,byte 2 ; DX -> IER xor al,al ; IRQ disable call slow_out @@ -1068,6 +1072,10 @@ pc_serial: call getint ; "serial" command jmp short parse_config_3 +.serial_port_bad: + mov [SerialPort], word 0 + jmp short parse_config_3 + pc_fkey: sub ah,'1' jnb pc_fkey1 mov ah,9 ; F10 |