From: "H. Peter Anvin" <hpa@zytor.com>
To: Miles Fidelman <mfidelman@meetinghouse.net>
Cc: Matthew Garrett <mjg@redhat.com>,
linux-kernel@vger.kernel.org, tglx@linutronix.de,
mingo@redhat.com, x86@kernel.org, peter.chubb@nicta.com.au,
michael.d.labriola@gmail.com
Subject: Re: reboot via bios on X86_64?
Date: Mon, 09 Apr 2012 10:53:07 -0700 [thread overview]
Message-ID: <4F832203.1010104@zytor.com> (raw)
In-Reply-To: <4F831BD0.3010707@meetinghouse.net>
On 04/09/2012 10:26 AM, Miles Fidelman wrote:
> Thanks for the quick response.
>
> Matthew Garrett wrote:
>> 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.
>
> That would explain it. I guess there's a little bit of trickiness
> involved in setting things up before
> switching to real mode.
>
Actually this code already exists; the difference is that we have to
return to 32-bit mode first.
-hpa
next prev parent reply other threads:[~2012-04-09 17:53 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-09 15:39 reboot via bios on X86_64? Miles Fidelman
2012-04-09 15:51 ` Matthew Garrett
2012-04-09 17:26 ` Miles Fidelman
2012-04-09 17:32 ` Matthew Garrett
2012-04-09 17:57 ` Miles Fidelman
2012-04-09 17:59 ` H. Peter Anvin
2012-04-09 18:06 ` Miles Fidelman
2012-04-09 18:07 ` Matthew Garrett
2012-04-10 14:03 ` Miles Fidelman
2012-04-10 14:22 ` Matthew Garrett
2012-04-10 17:26 ` Miles Fidelman
2012-04-10 17:44 ` Matthew Garrett
2012-04-10 18:09 ` Miles Fidelman
2012-04-09 17:53 ` H. Peter Anvin [this message]
2012-04-09 18:07 ` Miles Fidelman
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