diff options
| author | H. Peter Anvin <hpa@zytor.com> | 2009-09-04 17:19:09 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2009-09-04 17:21:10 -0700 |
| commit | 779a360023f47def89666923653d3ec59483a036 (patch) | |
| tree | af43a1aa5b239558b1594655dc0a230706a31206 /core | |
| parent | 96281dc8bf8189add880d8f2bedf104e6517d1f7 (diff) | |
| download | syslinux-779a360023f47def89666923653d3ec59483a036.tar.gz | |
core: when enabling serial IRQs, unmask interrupts at the PIC
Some BIOSes only enable interrupts in active use by the BIOS at the
PIC, which presumably don't include the serial ports. As such, enable
the interrupt lines at the PIC and hope to $DEITY we don't hang due to
a stuck interrupt line.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'core')
| -rw-r--r-- | core/serirq.inc | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/core/serirq.inc b/core/serirq.inc index 579c42b4..6babacec 100644 --- a/core/serirq.inc +++ b/core/serirq.inc @@ -91,6 +91,9 @@ SerialIRQPort dw 0 ; Serial port w IRQ service SerialHead dw 0 ; Head of serial port rx buffer SerialTail dw 0 ; Tail of serial port rx buffer + section .bss +IRQMask resw 1 ; PIC IRQ mask status + section .text sirq_install: @@ -133,6 +136,22 @@ sirq_install: mov al,1 ; Enable receive interrupt slow_out dx,al + ; + ; Enable all ther interupt lines at the PIC. Some BIOSes + ; only enable the timer interrupts and other interrupts + ; actively in use by the BIOS. + ; + in al,0xA1 ; Secondary PIC mask register + mov ah,al + in al,0x21 ; Primary PIC mask register + mov [IRQMask],ax + + io_delay + + xor ax,ax ; Remove all interrupt masks + out 0x21,al + out 0xA1,al + popad ret @@ -156,6 +175,12 @@ sirq_cleanup_nowipe: xor ax,ax slow_out dx,al ; Clear IER + ; Restore PIC masks + mov ax,[IRQMask] + out 0x21,al + mov al,ah + out 0xA1,al + ; Restore the original interrupt vectors mov si,oldirq0 mov di,4*08h |