From: Dmitry Torokhov on
On May 27, 2010, at 5:46 PM, Linus Torvalds <torvalds(a)linux-foundation.org
> wrote:

>
>
> On Thu, 27 May 2010, Robert Hancock wrote:
>>
>> It's highly unlikely that they are incomplete in this respect, as
>> since I mentioned, Windows would fail to recognize the PS/2
>> controller
>> that people would expect to work, which would most likely get
>> noticed..
>
> Did you miss the part where I actually quoted my own modern Core i5
> machine that _does_ have a keyboard controller, and _does_ have a
> keyboard
> port, and that does _not_ mention them in the PnP tables?

Except that it _does_. But _our_ ACPI implementation drops all
inactive devices so our PNP layer does not see your mouse and keyboard
ports.


>
>> I think this is a case where it has to be trusted, because that's
>> what
>> Windows does.
>
> The thing is, Windows isn't used for things like headless machines.
> Which
> we went over extensively in the thread. There's a _reason_ why Linux
> probes the dang thing.


--
Dmitry


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From: Mike Frysinger on
On Fri, May 14, 2010 at 11:16, Linus Torvalds wrote:
> On Fri, 14 May 2010, Matthew Garrett wrote:
>> I've done some experimentation under qemu. On ACPI systems, Windows will
>> *only* touch the keyboard controller if there's a device with an
>> appropriate PNP HID or CID and if _STA evaluates to 0x0b or 0x0f.
>> Otherwise it'll simply ignore the hardware entirely. By the looks of it
>> their keyboard probing is also somewhat different to ours, but that's
>> probably another story.
>
> Well, I'd hate to lose the keyboard hotplug capability, but at the same
> time, it _is_ 2010, and while I have personally used it historically, I
> don't really foresee ever using it again.
>
> So we _could_ decide to just try it, and see if anybody screams. If nobody
> does, that would be a very simple solution to the problem.

i still actively use it on my linux router (normally headless and no
input), as well as my main desktop from time to time :x. although
"actively" might not be the correct term as i dont usually have to
poke my linux router anymore ... it doesnt break very often anymore
which means i dont plug in anything at all.
-mike
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From: Robert Hancock on
On 05/27/2010 07:03 PM, Dmitry Torokhov wrote:
> On May 27, 2010, at 5:46 PM, Linus Torvalds
> <torvalds(a)linux-foundation.org> wrote:
>
>>
>>
>> On Thu, 27 May 2010, Robert Hancock wrote:
>>>
>>> It's highly unlikely that they are incomplete in this respect, as
>>> since I mentioned, Windows would fail to recognize the PS/2 controller
>>> that people would expect to work, which would most likely get
>>> noticed..
>>
>> Did you miss the part where I actually quoted my own modern Core i5
>> machine that _does_ have a keyboard controller, and _does_ have a
>> keyboard
>> port, and that does _not_ mention them in the PnP tables?
>
> Except that it _does_. But _our_ ACPI implementation drops all inactive
> devices so our PNP layer does not see your mouse and keyboard ports.

That's likely true - my machine works similarly, it doesn't list any
keyboard or mouse controller in PnP and Windows doesn't see them if no
device is plugged in at boot. The PnP devices for them are still
defined, but they are marked as disabled (the _STA method in the DSDT
returns 0). So we could likely detect that case and say "hey, the device
is there, just turned off, maybe we should try and see if it works
anyway". Whereas if the device is not there at all, we'd likely be
better off leaving it alone, by default anyway.

>
>
>>
>>> I think this is a case where it has to be trusted, because that's what
>>> Windows does.
>>
>> The thing is, Windows isn't used for things like headless machines. Which
>> we went over extensively in the thread. There's a _reason_ why Linux
>> probes the dang thing.
>
>

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From: Dmitry Torokhov on
On Thu, May 27, 2010 at 10:05:52PM -0600, Robert Hancock wrote:
> On 05/27/2010 07:03 PM, Dmitry Torokhov wrote:
> >On May 27, 2010, at 5:46 PM, Linus Torvalds
> ><torvalds(a)linux-foundation.org> wrote:
> >
> >>
> >>
> >>On Thu, 27 May 2010, Robert Hancock wrote:
> >>>
> >>>It's highly unlikely that they are incomplete in this respect, as
> >>>since I mentioned, Windows would fail to recognize the PS/2 controller
> >>>that people would expect to work, which would most likely get
> >>>noticed..
> >>
> >>Did you miss the part where I actually quoted my own modern Core i5
> >>machine that _does_ have a keyboard controller, and _does_ have a
> >>keyboard
> >>port, and that does _not_ mention them in the PnP tables?
> >
> >Except that it _does_. But _our_ ACPI implementation drops all inactive
> >devices so our PNP layer does not see your mouse and keyboard ports.
>
> That's likely true -

This was not a guess - I have seen DSDT from Linus' box.

That is why I said I'd be happy applying Metthew's patch if our ACPI did
not drop inactive devices - it would leave Apple and newer boxes alone
while still allowing plugging in keyboard/mouse in boxes that do have
i8042 even if BIOS decided to hide it from Windows.

--
Dmitry
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