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cpu/x86/lapic/lapic.c: Set spurious interrupt vector to 0xF

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The MP Specification v1.4 says to program the spurious interrupt
in the following way:

"The APIC spurious interrupt must point to a vector whose lower
nibble is 0F, that is 0xF, where x is 0 - F. Here we use Int 00FH,
which handles spurious interrupts and supplies the necessary IRET.
This vector is assumed to have already been initialized in memory."

Follow the requirement and set the spurious interrupt vector
to 0x0F. This is what reference implementations, like EDK2, and also
BIOS vendors do.

Change-Id: I7bde413bbadca1de0079daf52b5501ba6638a4c3
Signed-off-by: Michał Żygowski <michal.zygowski@3mdeb.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/89736
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
This commit is contained in:
Michał Żygowski 2025-10-24 13:22:24 +02:00 • committed by Matt DeVillier
commit 8795680828
1 changed files with 2 additions and 2 deletions
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4
src/cpu/x86/lapic/lapic.c
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@ -76,9 +76,9 @@ void setup_lapic_interrupts(void)
*/
lapic_update32(LAPIC_TASKPRI, ~LAPIC_TPRI_MASK, 0);
/* Set spurious interrupt vector to 0 and keep LAPIC enabled to
/* Set spurious interrupt vector to 0xF and keep LAPIC enabled to
be able to clear LVT register mask bits. */
lapic_update32(LAPIC_SPIV, ~LAPIC_VECTOR_MASK, LAPIC_SPIV_ENABLE);
lapic_update32(LAPIC_SPIV, ~LAPIC_VECTOR_MASK, LAPIC_SPIV_ENABLE | 0xF);
/* Put the local APIC in virtual wire mode */
uint32_t mask = LAPIC_LVT_MASKED | LAPIC_LVT_LEVEL_TRIGGER | LAPIC_INPUT_POLARITY |