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authorNico Huber <nico.huber@secunet.com>2012-09-24 10:48:43 +0200
committerPatrick Georgi <patrick@georgi-clan.de>2012-10-29 09:36:33 +0100
commit23c046b6f16805ff0131460189967bf261d704de (patch)
treee970aeb53075099b8562069f63c875a18174b769 /src/arch/x86/lib/ioapic.c
parentf4ff56f6173df256589dfdaee4cd1e7cafd0202c (diff)
Fix reading of number of interrupts for IO-APICs
The number read from the io-apic register represents the index of the highest interrupt redirection entry, i.e. the number of interrupts minus one. Change-Id: I54c992e4ff400de24bb9fef5d82251078f92c588 Signed-off-by: Nico Huber <nico.huber@secunet.com> Reviewed-on: http://review.coreboot.org/1624 Tested-by: build bot (Jenkins) Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Diffstat (limited to 'src/arch/x86/lib/ioapic.c')
-rw-r--r--src/arch/x86/lib/ioapic.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/src/arch/x86/lib/ioapic.c b/src/arch/x86/lib/ioapic.c
index 57b99e283e..018a42c173 100644
--- a/src/arch/x86/lib/ioapic.c
+++ b/src/arch/x86/lib/ioapic.c
@@ -85,8 +85,11 @@ void setup_ioapic(u32 ioapic_base, u8 ioapic_id)
/* Read the available number of interrupts. */
ioapic_interrupts = (io_apic_read(ioapic_base, 0x01) >> 16) & 0xff;
- if (!ioapic_interrupts || ioapic_interrupts == 0xff)
- ioapic_interrupts = 24;
+ if (ioapic_interrupts == 0xff)
+ ioapic_interrupts = 23;
+ ioapic_interrupts += 1; /* Bits 23-16 specify the maximum redirection
+ entry, which is the number of interrupts
+ minus 1. */
printk(BIOS_DEBUG, "IOAPIC: %d interrupts\n", ioapic_interrupts);
#if CONFIG_IOAPIC_INTERRUPTS_ON_FSB