Probe for the existance of legacy PIC, if one does not exist, use the
null_legacy_pic.
This patch implements the proposal put forth by H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>.
Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/mshyperv.c | 2 --
arch/x86/kernel/i8259.c | 11 +++++++++++
2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 47359f7..9ca9587 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -133,8 +133,6 @@ static void __init ms_hyperv_init_platform(void)
printk(KERN_INFO "HyperV: LAPIC Timer Frequency: %#x\n",
lapic_timer_frequency);
- printk(KERN_INFO "HyperV: Using null_legacy_pic\n");
- legacy_pic = &null_legacy_pic;
}
#endif
diff --git a/arch/x86/kernel/i8259.c b/arch/x86/kernel/i8259.c
index 2e977b5..0a57a19 100644
--- a/arch/x86/kernel/i8259.c
+++ b/arch/x86/kernel/i8259.c
@@ -299,11 +299,22 @@ static void unmask_8259A(void)
static void init_8259A(int auto_eoi)
{
unsigned long flags;
+ unsigned char probe_val = 0xfb;
i8259A_auto_eoi = auto_eoi;
raw_spin_lock_irqsave(&i8259A_lock, flags);
+ /* Check to see if we have a PIC */
+ outb(probe_val, PIC_MASTER_IMR);
+ probe_val = inb(PIC_MASTER_IMR);
+ if (probe_val == 0xff) {
+ printk(KERN_INFO "Using NULL legacy PIC\n");
+ legacy_pic = &null_legacy_pic;
+ raw_spin_unlock_irqrestore(&i8259A_lock, flags);
+ return;
+ }
+
outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */
outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */
--
1.7.4.1
_______________________________________________
devel mailing list
devel@xxxxxxxxxxxxxxxxxxxxxx
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
