diff options
Diffstat (limited to 'init.c')
| -rw-r--r-- | init.c | 11 |
1 files changed, 11 insertions, 0 deletions
@@ -234,6 +234,11 @@ init_pcb (void) static void init_i8259 (void) { + /* ??? MILO initializes the PIC as edge triggered; I do not know how SRM + initializes them. However, Linux seems to expect that these are level + triggered. That may be a kernel bug, but level triggers are more + reliable anyway so lets go with that. */ + /* Initialize the slave PIC. */ outb(0x11, PORT_PIC2_CMD); /* ICW1: edge trigger, cascade, ICW4 req */ outb(0x08, PORT_PIC2_DATA); /* ICW2: irq offset = 8 */ @@ -246,6 +251,12 @@ init_i8259 (void) outb(0x04, PORT_PIC1_DATA); /* ICW3: slave control INTC2 */ outb(0x01, PORT_PIC1_DATA); /* ICW4 */ + /* Initialize level triggers. The CY82C693UB that's on real alpha + hardware doesn't have this; this is a PIIX extension. However, + QEMU doesn't implement regular level triggers. */ + outb(0xff, PORT_PIC2_ELCR); + outb(0xff, PORT_PIC1_ELCR); + /* Disable all interrupts. */ outb(0xff, PORT_PIC2_DATA); outb(0xff, PORT_PIC1_DATA); |