[PATCH] i386: Handle non existing APICs without panicing

[description from AK]

This fixes booting in APIC mode on some ACER laptops. x86-64
did a similar change some time ago.

See http://bugzilla.kernel.org/show_bug.cgi?id=4700 for details

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 12 insertions, 4 deletions

diff --git a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c
index f2dd218d88cb..235822b3f41b 100644
--- a/arch/i386/kernel/io_apic.c
+++ b/arch/i386/kernel/io_apic.c
@@ -2566,8 +2566,10 @@ int __init io_apic_get_unique_id (int ioapic, int apic_id)
                 spin_unlock_irqrestore(&ioapic_lock, flags);
 
                 /* Sanity check */
-                if (reg_00.bits.ID != apic_id)
-                        panic("IOAPIC[%d]: Unable change apic_id!\n", ioapic);
+                if (reg_00.bits.ID != apic_id) {
+                        printk("IOAPIC[%d]: Unable to change apic_id!\n", ioapic);
+                        return -1;
+                }
         }
 
         apic_printk(APIC_VERBOSE, KERN_INFO
diff --git a/arch/i386/kernel/mpparse.c b/arch/i386/kernel/mpparse.c
index e7609abf3796..e6e2f43db85e 100644
--- a/arch/i386/kernel/mpparse.c
+++ b/arch/i386/kernel/mpparse.c
@@ -915,6 +915,7 @@ void __init mp_register_ioapic (
         u32                     gsi_base)
 {
         int                     idx = 0;
+        int                     tmpid;
 
         if (nr_ioapics >= MAX_IO_APICS) {
                 printk(KERN_ERR "ERROR: Max # of I/O APICs (%d) exceeded "
@@ -935,9 +936,14 @@ void __init mp_register_ioapic (
 
         set_fixmap_nocache(FIX_IO_APIC_BASE_0 + idx, address);
         if ((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) && (boot_cpu_data.x86 < 15))
-                mp_ioapics[idx].mpc_apicid = io_apic_get_unique_id(idx, id);
+                tmpid = io_apic_get_unique_id(idx, id);
         else
-                mp_ioapics[idx].mpc_apicid = id;
+                tmpid = id;
+        if (tmpid == -1) {
+                nr_ioapics--;
+                return;
+        }
+        mp_ioapics[idx].mpc_apicid = tmpid;
         mp_ioapics[idx].mpc_apicver = io_apic_get_version(idx);
         
         /*