Messages in this thread Patch in this message | | | From | Bandan Das <> | Subject | [PATCH] x86/apic: remove read/write test in verify_local_apic() | Date | Wed, 18 Mar 2015 16:45:54 -0400 |
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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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