Re: [PATCH v3] x86, vt-d: enable x2apic opt out
From: Valdis . Kletnieks
Date: Mon May 23 2011 - 22:25:26 EST
On Mon, 23 May 2011 22:32:28 +0800, Youquan Song said:
> + no_x2apic_optout [Default Off]
> + With this option BIOS x2APIC opt-out request will be
> + ignored.
> + else if (!x2apic_supported() && cpu_has_x2apic)
> + WARN(1, "Your BIOS is broken and requested that x2apic be "
> + "disabled.\n This will leave your machine vulnerable to"
> + " irq-injection attacks\n"
> + "Use 'intel_iommu=no_x2apic_optout' to override BIOS "
> + "request\n");
If we're doing a WARN level here, what are the downsides of just automagically
forcing it rather than making them use a kernel parameter and reboot? Will
some systems fail to boot because the BIOS was in fact right in requesting
hat x2apic be turned off?
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