linux-kernel - Re: [PATCH]X86:reboot.c Add some dmi entries to pci_reboot_dmi

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Message-ID: <4C06F8B0.1010805@gmail.com>
Date:	Wed, 02 Jun 2010 18:34:56 -0600
From:	Robert Hancock <hancockrwd@...il.com>
To:	"Justin P. Mattock" <justinmattock@...il.com>
CC:	Matthew Garrett <mjg59@...f.ucam.org>, x86@...nel.org,
	tglx@...utronix.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH]X86:reboot.c Add some dmi entries to pci_reboot_dmi_table.

On 06/02/2010 06:27 PM, Justin P. Mattock wrote:
> On 06/02/2010 05:20 PM, Robert Hancock wrote:
>> On Wed, Jun 2, 2010 at 6:05 PM, Justin P. Mattock
>> <justinmattock@...il.com> wrote:
>>>>>> Hmm, so the FADT says the reset register is listed as supported, and
>>>>>> says writing 0x06 to 0xCF9 is supposed to do it.. That's exactly what
>>>>>> this should do:
>>>>>>
>>>>>> #include<sys/io.h>
>>>>>>
>>>>>> int main() {
>>>>>> iopl(3);
>>>>>> outb(6, 0xcf9);
>>>>>> return 0;
>>>>>> }
>>>>>>
>>>>>> but you said that didn't do anything.. It kind of seems like ACPI
>>>>>> reboot is busted on this machine then, but then I wonder how Windows
>>>>>> manages to work..
>>>>>>
>>>>>
>>>>>
>>>>> alright!! I have a better idea at what this is now..
>>>>> as for the above code, yes this one segfaults,
>>>>> the other code posted on the thread just returns
>>>>> a command prompt(testing:
>>>>
>>>> You get a segfault on that one? Running as root?
>>>>
>>>
>>> my bad(tired)I left out iopl(3);
>>> in the code which was giving a segfault.
>>>
>>> running the below code(s) just gives a command prompt
>>>
>>> int main() {
>>> iopl(3);
>>> outb(0xfe, 0xcf9);
>>> return 0;
>>> }
>>>
>>> int main() {
>>> iopl(3);
>>> outb(6, 0xcf9);
>>> return 0;
>>> }
>>
>> What if you do:
>>
>> #include<unistd.h>
>>
>> int main() {
>> iopl(3);
>> outb(2, 0xcf9);
>> sleep(1);
>> outb(6, 0xcf9);
>> return 0;
>> }
>>
>> That's basically what PCI reboot does.
>>
>> It's possible it doesn't take the first time - you could try modifying
>> drivers/acpi/reboot.c to call acpi_reset in a loop instead of just
>> trying once (assuming you have the patch to default to ACPI reboot
>> enabled).
>>
>
> the above code reboot's the machine as it should..
> I can look at that(need to take a break first though)
> and see..
>
> what about the whole kbd mechanism(0x64) give the info I provided
> does it look possible, or is this machine strictly on cf9?

The keyboard controller reset is the kernel default, so I assume that 
doesn't work on this machine or else this wouldn't have come up in the 
first place..
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