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Subject[PATCH] x86/apic: remove read/write test in verify_local_apic()
Date

Most newer processors have the APIC_ID read-only and this
test probably fails on most boxes anyway. Fix typos.

Signed-off-by: Bandan Das <bsd@redhat.com>
---
Honestly, I don't think this function is really needed.
It's called for both UP/MP but the return value isn't
used by any of them. Maybe, we should just remove it ?

arch/x86/kernel/apic/apic.c | 18 +++++++-----------
1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index ad3639a..d54601e 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1105,13 +1105,13 @@ int __init verify_local_APIC(void)
/*
* The two version reads above should print the same
* numbers. If the second one is different, then we
- * poke at a non-APIC.
+ * are poking at a non-APIC region.
*/
if (reg1 != reg0)
return 0;

/*
- * Check if the version looks reasonably.
+ * Check if the version looks reasonable.
*/
reg1 = GET_APIC_VERSION(reg0);
if (reg1 == 0x00 || reg1 == 0xff)
@@ -1121,21 +1121,17 @@ int __init verify_local_APIC(void)
return 0;

/*
- * The ID register is read/write in a real APIC.
+ * Just print the APIC ID
+ * Writing to it is not a reliable test - older processors
+ * support it, while newer processors don't
*/
reg0 = apic_read(APIC_ID);
- apic_printk(APIC_DEBUG, "Getting ID: %x\n", reg0);
- apic_write(APIC_ID, reg0 ^ apic->apic_id_mask);
- reg1 = apic_read(APIC_ID);
- apic_printk(APIC_DEBUG, "Getting ID: %x\n", reg1);
- apic_write(APIC_ID, reg0);
- if (reg1 != (reg0 ^ apic->apic_id_mask))
- return 0;
+ apic_printk(APIC_DEBUG, "Getting Local APIC ID: %x\n", reg0);

/*
* The next two are just to see if we have sane values.
* They're only really relevant if we're in Virtual Wire
- * compatibility mode, but most boxes are anymore.
+ * compatibility mode, but most boxes aren't anymore.
*/
reg0 = apic_read(APIC_LVT0);
apic_printk(APIC_DEBUG, "Getting LVT0: %x\n", reg0);
--
2.1.0


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