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Date: Mon, 9 Apr 2012 16:51:55 +0100 From: Matthew Garrett <mjg@...hat.com> To: Miles Fidelman <mfidelman@...tinghouse.net> Cc: linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...hat.com, hpa@...or.com, x86@...nel.org, peter.chubb@...ta.com.au, michael.d.labriola@...il.com Subject: Re: reboot via bios on X86_64? On Mon, Apr 09, 2012 at 11:39:32AM -0400, Miles Fidelman wrote: > 1. What's the logic behind this? Why not enable a bios reboot for 64bit > kernels? Is there any reason why the machine_real_restart code wouldn't > work just as well in 64bit mode? Anybody know the history? The bios reboot code requires you to reprogram the CPU to real mode. I don't think there's any fundamental reason you can't do that from 64-bit mode, but nobody's ever written that code. > 2. Anybody know a workaround, short of patching and compiling a custom > kernel? Are there other paths through the reboot code that can > invoke a bios > reboot? [Note: someone suggested trying a kexec-reboot, but that's also > not supported on my configuration (running over a Xen hypervisor).] Windows never uses the equivalent of the BIOS reboot method, so the assumption is that if you ever need on Linux to it's because there's a bug somewhere else. Does the platform reboot if you run the kernel on bare metal rather than under Xen? -- Matthew Garrett | mjg59@...f.ucam.org -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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