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| author | Thomas Gleixner <tglx@linutronix.de> | 2020-02-26 00:36:41 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-02-27 16:48:40 +0300 |
| commit | d244d0e195bc12964bcf3b8eef45e715a7f203b0 (patch) | |
| tree | 498b0e5ed2884d25e45436caf6c4a13f3eb8b92a | |
| parent | e039dd815941e785203142261397da6ec64d20cc (diff) | |
| download | linux-d244d0e195bc12964bcf3b8eef45e715a7f203b0.tar.xz | |
x86/traps: Document do_spurious_interrupt_bug()
Add a comment which explains why this empty handler for a reserved vector
exists.
Requested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200225220216.624165786@linutronix.de
| -rw-r--r-- | arch/x86/kernel/traps.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 474b8cb54899..7ffb6f4dea1c 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -862,6 +862,25 @@ do_simd_coprocessor_error(struct pt_regs *regs, long error_code) dotraplinkage void do_spurious_interrupt_bug(struct pt_regs *regs, long error_code) { + /* + * This addresses a Pentium Pro Erratum: + * + * PROBLEM: If the APIC subsystem is configured in mixed mode with + * Virtual Wire mode implemented through the local APIC, an + * interrupt vector of 0Fh (Intel reserved encoding) may be + * generated by the local APIC (Int 15). This vector may be + * generated upon receipt of a spurious interrupt (an interrupt + * which is removed before the system receives the INTA sequence) + * instead of the programmed 8259 spurious interrupt vector. + * + * IMPLICATION: The spurious interrupt vector programmed in the + * 8259 is normally handled by an operating system's spurious + * interrupt handler. However, a vector of 0Fh is unknown to some + * operating systems, which would crash if this erratum occurred. + * + * In theory this could be limited to 32bit, but the handler is not + * hurting and who knows which other CPUs suffer from this. + */ } dotraplinkage void |