[Xen-devel] Re: 3.0.4 and 3.1-rc4 based dom0 won't boot with acpi=off

[Sven Köhler <sven.koehler@xxxxxxxxx>]

Am 12.09.2011 17:06, schrieb Konrad Rzeszutek Wilk:
> On Sun, Sep 11, 2011 at 02:44:35AM +0200, Sven Köhler wrote:
>> Am 11.09.2011 02:28, schrieb Konrad Rzeszutek Wilk:
>>> You might want to try some parameters on the Xen line to alter how
>>> it is suppose to reboot.
>>>
>>> /*
>>>  * reboot=b[ios] | t[riple] | k[bd] | n[o] [, [w]arm | [c]old]
>>
>> Thanks for the list.
>> I guess, both reboot=bios and reboot=b is accepted?
>> BTW: "no" is missing in the list below. acpi is missing in the list
>> above. And actually what's the source for list?
> 
> Xen hypervisor source. I just did a quick search for 'reboot='

I checked the sources of Linux 3.1rc4 and he xen hypervisor (4.1.1).
The code for reboot is almost the same. One tiny difference is that the
code of xen sets the reset flag of the kbd controller 100 times, while
Linux does that only 10 times:

Xen:
>             for ( i = 0; i < 100; i++ )
>             {
>                 kb_wait();
>                 udelay(50);
>                 outb(0xfe,0x64); /* pulse reset low */
>                 udelay(50);
>             }

Linux:
>                         for (i = 0; i < 10; i++) {
>                                 kb_wait();
>                                 udelay(50);
>                                 outb(0xfe, 0x64); /* pulse reset low */
>                                 udelay(50);
>                         }


Summing up, both Linux 3.1 and Xen 4.1 both do the following sequence by
default:

ACPI, KBD, ACPI, KBD, TRIPLE, KBD, TRIPLE, KBD, ...

While each KBD stands for 10 (Linux) or 100 (Xen) times setting the kbd
controller reset flag. I wonder why Xen does the kbd controller reset a
hundred times. Maybe it's a left over from xen 3.x?

Would you mind changing it from 100 to 10?


Now taking a look at Xen 3.4.2, the default reboot sequence is a bit
different. It's

ACPI, KBD, ACPI, KBD, ACPI, KBD, ACPI, KBD, ....

No triple fault reset attempts.



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